Around Basel: The Rheintalflexur – some background information and observations

Let me now follow up on the Rheintalflexur or “Rhine Valley flexure”, reading more about it and observing it in nature.

Let us do so after having thought about the earthquake of 1356 and the emergence of the Rhine Rift Valley (Rheintalgraben).


Gathering information about the geology of the Rheintalflexur 

In the lecture notes provided by the Basel university, I found this geological cross section of the Rheintalflexur from the Wartenberg (via Muttenz) to the Bruderholz. The sediments bent are shown here, and they flexed, when the crystalline basement cracked down.

The Rheintalflexur is rather exotic in the Rhine Rift Valley. At the flexure, the fractures are about 1000m deep, whereby farther north the rift slid down up to 4000m. While extension had caused the cracking of the rift valley, compression seems to act now at the Rheintalflexur (Laubscher, 1971, p. 157). We are at the southern end of the rift valley, where it turns to the west to form the Belfort gap, and somehow the rift had to “find a way” to complete the “turning” which lead to a complex pattern of small cracks. The Tafeljura echoed that with the fractions of the Wartenberg and the Adler.


The “Schänzli”: Building the highway tunnel allowed to explore the “Rheintalflexur”

This often cited graph of Buxtorf illustrates, how steeply the layers bend under the Schänzli (he assumed the fault to be reverse). The tunnel of the highway T18 going south to the Birseck was built exactly here, at the Schänzli.

Source: Hans Laubscher, 1971

Below we see the cross section of the highway tunnel  “Schänzli” that «sits» on the fault line and reaches into the layers of lime stone that are almost vertical here. Stairs allow now to enter and observe the geological activity (left). 

Source: Website “Heimatkunde Muttenz

During the excavation for the tunnel, the almost vertical layers of lime (Hauptrogenstein) were temporarily uncovered (right).

Let us now go out and shoot some photos to illustrate the tracks of Rheintalflexur. 


The Rheintalflexur at the Birs

The concrete pier of the wooden bridge at Münchenstein crossing the river Birs sits on the Rheintalflexur. Between the two pillars, we can see, how the  sediment layers are inclined. 

Just above the bridge there is the cataract formed by the slanting sediment layers of the flexure. 

I remember that I stood here with our geography teacher more than fifty years ago and he talked about the flexure.

Before taking these photos, I looked for the flexure walking up and down along the Birs; people kept on asking me, whether I had seen the kingfisher. The kingfisher? “No”, I replied, “I look for the “Rheintalflexur””. “You look for what?” – and  then I had some long conversations. May be, one day I should also look for the kingfisher.

Beyond the Rheintalflexur the Tafeljura cracked into “pieces”, and the Wartenberg was tilted (see the geological cross section above). The tilted layers of the Wartenberg “ditch” can be seen at various places. This is a photo from the quarry above the vineyards. Or is it here, where part of the landslide broke off in 1952? 

A dog sniffs at my shoes. The lady asks me: “Do you  take a photo, before it all slides down?”. And then she continues: “The slopes are very unstable here, a gap keeps on appearing that is being closed again and again to “hide it”. We have built our house on rocks, after having consulted a geologist. At the Wartenberg, you should never build a house without consulting a geologist.” Okay, well I had never planned to build a house here, my mum had always warned me about the Wartenberg…


More signs of the Rheintalflexur: The quarry above Münchenstein

Above Münchenstein, in the quarry “Blinden”, the bending sediments of the Rheintalflexur are also uncovered. 

The quarry is no longer in use. It has become a romantic nature reserve, even with a picnic place (as there are lots of them around Basel, some even providing free firewood).

During my next walk on the Bruderholz, I discover the quarry across, above Münchenstein. I have never noticed it from here, though having been here hundreds of times. Yes, we notice, what we have read about and thought about before! Not only, when travelling to other countries, but also, when walking around home.


Looking for the”Rheintalflexur in the landscape park “Ermitage” – not really successful

The Ermitage of Arlesheim is a marvellous landscape park, first established in 1785 and reconstructed in 1811. I have blogged about it in 2015 at the occasion of the park’s 230th anniversary.

The heart of the landscape park is under the Birseck castle. This castle is a ruin, integrated into the Ermitage, as every “proper” landscape park must have a ruin. A maze of footpaths zigzags up and down the rocky slope under the castle. The wall of the so-called “carousel square” stands out at the foot of the hill. 

Some 150 million years ago, this hill was part of a riff at the shore of the former Tethys sea, long before the Rhine Rift Valley emerged (40 million years ago). Many natural caves emerged later that create an exceptional atmosphere to the park.

I could not find identify the flexure around the Ermitage. May be the rock above the “carousel square” is part of it? Erich Plattner’s “Höhlen der Ermitage” does not help either, as what he calls “geological cross section of the Ermitage” seems to be farther north (from the Predigerhof across Arlesheim to the Hinteri Ebni, p. 47).  

Not really successful. Anyway, I do love to stroll through this magnificent landscape park that hides many surprises such as the hut of the “Waldbruder” or “brother of the woods”. Now, in winter, his hut can be seen from far.

The architects of the Ermitage created their landscape park with a lot of phantasy, and I keep on discovering new details.


The “Rheintalflexur” at the Hornfelsen (Dinkelberg)

The Rheintalflexur can be seen above Grenzach (already in Germany) at the Hornfelsen,…  

… where in particular the “lowest” rocks are bending clearly downwards. 

Also here I have been so many times before and have never noticed the flexure. 

I would love to find a book about the geological phenomena around Basel explaining them and informing, where they can be seen in nature. A book for interested hikers such as our group of Nordic Walkers. 


Hans Laubscher, Das Problem von Rheintalflexur und Tafeljura, Eclogae Geologicae Helvetiae, 64 (1971), Heft 1; 

Peter Huggenberger, Lecture Notes “Jura Tektonik”, Department of Environmental Sciences, University of Basel (Überblick (Di ) Teil 2 Tafeljura (Do ) – PDF Free Download (

Erich Plattner, ” Die Höhlen der Ermitage bei Arlesheim”, Speleo Projects 2014.

Around Basel: The geology and causes for the earthquake of Basel

In my former blog, I have talked about the severe 1356 earthquake of Basel. Some 6.2 to 6.4 on the Richter scale, as Laubscher, 2006, says. We have seen the presumed destructive impact of the earthquake in the southern Rhine Rift valley, based on historical reports. 

Source: Werner Meyer, “da verfiele Basel überall”, Schwabe Verlag Basel 2006, p. 67

Red denotes castles destroyed and not rebuilt and blue shows castles or cities strongly affected, but rebuilt. Yellow are minor destructions or none, always according to the historical reports analyzed. 

To understand more of the geological facts causing the earthquake, let us follow up on these questions:

  • How did the Rhine Rift Valley come into existence?
  • What is peculiar about the southern end of the rift valley (around Basel)?
  • So, what might be the cause for the seismic activity around Basel and for the 1356 earthquake?


A glance at the southern end of the Rhine Rift Valley, around Basel

Basel is located at the southern end of the Rhine Rift valley. To get a feeling for that, let us first have a glance at four photos.

(1) Looking north from the eastern end of the Blauen Chain (Eggfluh), we can see the Birseck with the Gempen Plateau to the right and the Black Forest in the background. 

(2) Now we are on the Gempen Plateau in the Tabular Jura (Tafeljura near Hofstetten) and look westwards across the Birseck and the hills of the Sundgau, up to the faint blue line of the Vosges (Vogesen), with the highest peak being the Grand Ballon (France).

(3) Here I am in Germany on the foothills of the Schwarzwald/Black Forest (Markgräflerland) and look south at Basel, with the Gempen Plateau to the left and the folded chains of the Jura in the middle background, including the Blauen to the right.

(4) The fourth photo I took from the Remel at the western end of the Blauen looking northwards across the Sundgau to the Vosges (France). Basel is at about 20km to the right (east).

Yes, Basel is located at the southern end of the Rhine Rift Valley, surrounded by hills and mountains.


How did the Rhine Rift Valley come into existence?

The Rhine Rift Valley emerged long before the unfolding of the Alps and the Jura unfolded. This is a simplified description. 

  1. 150 to 200 million years ago, there was the sea called Tethys that deposited sediments on the ground, on the crystalline basement.
  2. About 40 million years ago, everything was lifted up which resulted in the basement and the sediments to break apart and slide downwards several thousand meters. 
  3. The Vosges and the Black Forest emerged, and in front of them foothills (Sundgau and Markgräfler Land). The volcano “Kaiserstuhl” erupted some 15-19 Mio years ago.
  4. The sediments from the sides were eroded filling the trough and uncovering the crystalline basements of the Vosges and the Black Forest. The mountains reach about 1500m, the base of the trough, filled with the sediments, is at around 250m above sea level.  

The four stages overlapped in time.

Source: My owns drawing to grasp the verbal descriptions on (very much simplified)


What is peculiar about the southern end of the rift valley (around Basel)?

The Rhine Rift Valley ends some 20kms south of Basel. The trough formation turned left (westwards) to form the Belfort gap and to continue as the Rhône-Saône Rift Valley up to the Mediterranean. 

The Dinkelberg and the Tabular Jura (Tafeljura) belong to the Black Forest, and they are lower. When the trough formed, their sediments bent down forming the so-called “Rheintalflexur” and more such flexures arose such as the Landskronflexur.  

Source: My own rough drawing to understand the descriptions on (very much simplified)

Later, 10 to 2 million years ago, the Alps and the Jura Chain (Faltenjura) were unfolded, and they covered part of the “old” Tabular Jura by some 5kms. This is called “reverse faulting”.

The Alps and the Jura were unfolded, when the European plate slid under the Adriatic/African plate. This is a simplified model of the collision of the two plates.

Source: Website ETH Zurich, knowledge about earthquakes

Laubscher points out that the plate border is not a “straight line”, but it stretches along 2000km, from the Atlas mountains in Africa to the Alps; Basel lies at the northern edge of this plate border “zone”. The convergence is still going on today: The European Plate pushes from North West and the Adriatic/African Plate from South East.


So, what might be the cause for the seismic activity around Basel and for the 1356 earthquake?

Let us recall the controversy I came across about the reasons of the earthquake of 1356 (as stated in my former blog):

  • At high school, I understood from our teacher, the Rhine Rift Valley and in particular the “Rheintalflexur” had caused the earthquake of 1356. The Birseck is, where in Meyer’s map much of the historically reported severe damages seem to have been reported, but not all. 
  • Hans-Peter Laubscher, “Zur Geologie des Erdbebens von Basel 1356” (in Werner Meyer, “Da verfiele Basel überall”, Schwabe Verlag Basel 2006) says that the seismic activity around Basel is probably the result of the convergence of the African and the European tectonic plates that “waked up” various fault lines around Basel. This would explain the fact that further serious damages had been reported beyond the Birseck, Blauen and Gempen.

Laubscher presents this map of the rift valley, along with the fault lines he is aware of and the pressures going on.

Source: Hans Peter Laubscher, “zur Geologie des Erdbebens von Basel 1356”, in Werner Meyer, “Da verfiele Basel überall”, Schwabe Verlag Basel 2006

As I understand Laubscher’s explanations, some fault lines such as the Rheintalflexur have been caused by the emergence of the Rhine Rift Valley (150-200 Mio years ago), but some other fault lines are much older, from 250-280 Mio years ago; at that time another earlier rift valley emerged (so called “permo-carbon trough”, see also Huggenberger), leaving “older” disturbances such as the Mandach-Monbéliard and the Mont-Terri. Laubscher says that the (older and newer) fault lines around Basel can be reactivated under new pressures. 

The convergence of the European and the African plates is such a “newer” source of pressure (see the arrows showing the pressures executed by the plates). Still today, the plates converge at 8mm/year. Most of this convergence is currently being absorbed south of the Alps, where the seismic activity is much higher than north of the Alps. The Rhine Rift Valley fault lines and the older disturbances (such as the Mandach-Monbéliard or Mont-Terri lines) are areas of weaknesses that can react, when the tectonic plates of Africa and Europe rub against each other. Laubscher believes that this was the reason for the earthquake in 1356: The lesions around Basel reacted to the convergence of the tectonic plates (p.212). As a matter of fact, the pattern of damages reported historically pretty much follows the (older) Mandach-Monbéliard and Mont-Terri disturbances. In case the destructions reported historically are not complete and there were more destructions north of the “Meyer’s ellipse”, then the Rheintalflexur with its north-south orientation could also have made their contribution, as Laubscher points out. 

On the geological map, arrows indicate the pressures along the Mont Terri Line and the Rheintalflexur. There is convergence (double arrows facing each other) as well as some sideward pushing (single arrow). The complex pattern of pressures is due to the fact that the convergence of the European and the African plate does not act at a right angle upon these fault lines. This makes predictions about seismic activity expected around Basel difficult. 

While Laubscher says that at Basel severe earthquakes happen less often than south of the Alps, “less often” does not exclude another serious earthquake to happen again. In 660 years, the geology has not changed that much, when I think of the millions of years that count in geology. As my mum, the geologist, had rightly pointed out to me, when I was nine years old. 

Well, I am not a geologist and I may not have consulted the latest research results. I have interpreted the sources I had at hand, and the basic story with the tectonic plates and the faults activated by their rubbing against one another causing earthquakes makes sense to me.  

Due to the pandemic of this year 2020, I will continue to walk mostly around Basel in the next months. It is amazing, how much I discover so close to my home. I intend to follow up on the geological evidence of the flexures around Basel. What I also always find amazing, are all these border stones along the hiking paths and in the woods that tell us about the world history that the area around Basel was part of. Being confined at home opens the eyes for what is so near. 



Around Basel: About the earthquake of Basel and its destructive impact

About 660 years ago, Basel was hit by an earthquake. With 6.2 to 6.4 on the Richter scale, it was one of the strongest earthquakes that we know of in Switzerland, perhaps even the strongest. 


At primary school, I first learnt about the earthquake of Basel

It was at primary school around 1960 that I first heard of the earthquake of Basel. In our “Heimatkundebuch” (book about local history and geography), we wrote down the poem that describes the year 1356 in medieval German interpreting the Roman numbers (MCCCLIIIIII).

This translates to: A ring with its thorn, three horseshoes selected , a carpenter’s ax and some jugs, at that time Basel was destroyed all over.

It was not so much the earthquake that damaged the city, but the subsequent fire, caused by open fireplaces in the houses and by burning candles in the churches (Werner Meyer: “Da verfiele Basel überall”, Schwabe Verlag Basel, 2006, p. 54f). This is how I imagined the fire devastating the city, when I was about nine years old. 

Phantasy is “allowed”. See, how Wurstisen imagined the earthquake in 1580 (Meyer, p. 53). 

I remember that our teacher reassured us: “This earthquake happened centuries ago. Today nothing like that will occur again.” I returned home and told my mum about the earthquake and that she should not worry about it, as it will not happen again. My mum, being a geologist, frowned at me: “Come on, the geology here is still the same, such an earthquake might happen again, any time.” Not very reassuring for me, but my mum was right. And she did not like untrue statements. 

The earthquake made a deep impression on me. I felt with bishop Johannes who, on the way from Delsberg to Basel, visited the damaged castle of Pfeffingen and was able to find his godchild safely protected under two blocks of stone. Our teacher read the story to us and we summarized it in an essay for our “Heimatkundebuch”. This is my essay, also full of phantasy.

Was this a legend? No, there is historical evidence available. Immediately after the earthquake, the prince-bishop of Basel, Johannes Senn (1335-1365), rode from Delsberg (or perhaps from St. Ursanne) to Basel, stopping by at the severely damaged castle Pfeffingen to participate in the rescue operation of his godchild (Meyer, p.113).

Here you can see the castle of Pfeffingen above the trees in the right hand foreground. Strategically well placed above the Birseck valley, it has been rebuilt after the earthquake. Across to the right is the Gempen plateau (with the greyish cliff lines). The blue mountains in the background are the southern Black Forest. I am standing on the Eggfluh that forms the eastern edge of the Blauen Chain and I look to the north.

I want to know more about the destructive impact of the earthquake and about the underlying geology.  


The destructive impact of the earthquake – historical evidence

“Our Burgenmeyer” analyzed the historical reports about the earthquake of Basel and illustrated them in this map: The castles definitely destroyed appear in red. Blue denotes the castles (circle) or cities (squares) that were heavily damaged and then reconstructed, and yellow indicates castles (triangles) or cities (squares) that were not or only slightly affected. 

Source: Werner Meyer, “da verfiele Basel überall”, Schwabe Verlag Basel 2006, p. 67

The damages reported formed an ellipse about 85kms wide, whereby the most severe damages occurred within a narrower ellipse about 45kms wide, the centre being south of Basel: In the Birseck, in the valley of the Birsig to the west and on the Gempen Plateau to the east; it is here, where the colours red (destroyed and not rebuilt) and blue (heavily damaged and reconstructed) dominate.

What might have been the reasons for the earthquake of 1356?

  • At high school, our teacher told us that the Rhine Rift Valley had caused the earthquake and that the epicentre was where the “Rheintalflexur” or “Rhine valley flexure” bends down from the Gempen into the Birseck. The Birseck is, where in Meyer’s map much of the severe damages seem to have been reported, but not all. 
  • Hans-Peter Laubscher, “Zur Geologie des Erdbebens von Basel 1356” (in Werner Meyer, “Da verfiel Basel überall”, Schwabe Verlag Basel 2006) says that the seismic activity around Basel is probably the result of the convergence of the African and the European tectonic plates that “wakes up” various fault lines around Basel. This would explain the fact that further severe damages occurred beyond the inner ellipse around Birseck, Blauen and Gempen, as the southern end of the Rhine Rift valley is full of disruptions.

To understand more about this controversy, I will check some geological facts in my next blog.


Source: Werner Meyer: “Da verfiele Basel überall”, Schwabe Verlag Basel, 2006

Around Basel: Hiking to Flüh discovering the gorgeous Chälegraabe

The area around Basel is full of secrets. 

Let us discover the Chälegrabe today. 

The Chälegrabe (5) is located south of Hofstetten. It is a gorge that deeply cuts into the slopes of the Blaueberg (also called Blauen chain or Blauenkette). 

I explored the Chälegrabe, when walking from Rodersdorf to Flüh in October 2020.


The Chälegrabe – why is this spectacular gorge called “Chäle”-“Grabe”?

With its name, the Chälegrabe says clearly: “I AM a “gorge” and I am telling you so twice: “Chäle” is an old word for “gorge” and “Grabe” is the current Swiss German word for “gorge”… I am the “Chälegrabe”, the “Gorge-gorge” or the “Grabe-Grabe”!” (Check, which confirms that “Chäle” is an old word for “gorge”).

Yes, the Chälegrabe is a “Gorge-gorge”, and I confirm, it is even a gorgeous “Gorge-gorge”!   


Let us walk through the Chälegrabe or “Gorge-gorge”

The access to the Chälegrabe is above the car park that is much used by hikers and dog owners. Here the signpost points to the Chälegrabe.

The Chälegrabe starts as a gentle creek with wooden bridges.

Then, I am approaching the rocks of the gorge,…

… and the rocks  are getting larger and narrower.

I pass by the picnic place…

… and climb up steeply on the zigzag path.

I cross the deep canyon…

… and walk along the gangway (no other way to continue in this narrow gorge-gorge)…

… with waterfalls below.

I go back down again…

… to pick up my bicycle at the car park.

I am pleased to have discovered the  gorgeous “Gorge-gorge” Chälegrabe. How often have I looked for such gorges around the world and have not been aware of this treasure so close from home, so close to Basel.


P.S. With the Chälegrabe, I have now completed the series of the five secrets found on my walk from Rodersdorf to Flüh in October 2020.  

  1. Historical border stones from the years 1817, 1890 and 1951 between France and Switzerland – why from 1817? And can you see the “D” (Germany or “D”eutschland) hidden “behind” the “F” for France? 
  2. Biederthal and its castle, Burg (Biederthal) – why are they separated by the border between France and Switzerland?
  3. Why does the canton of Solothurn (SO) “own” an exclave within Basel (BL)? What can the Burg Rotberg tell us about this?
  4. Why did the Romans dig a cart road (“Karrweg”) into the rocks to get from Flüh to Hofstetten – avoiding the valley? 
  5. The Chälegrabe above Hofstetten – why is this spectacular gorge called “Chäle”-Grabe”?

Secrets #1/#2 to #3/#4 are covered in two former blogs.

Around Basel: Historical secrets on the hike from Rodersdorf to Flüh (cted)

The area around Basel is full of secrets.  

Did you know that the family Rotberg sold the possessions around their castle Burg Rotberg to the canton of Solothurn?

The map shows the possessions that Solothurn bought; they are marked with “SO” and are surrounded by “BL” (Baselland).

Let us summarize the five secrets that I found, when walking from Rodersdorf to Flüh in 2020:

  1. Historical border stones from the years 1817, 1890 and 1951 between France and Switzerland – why from 1817? And can you see the “D” hidden “behind” the “F” for France? 
  2. Biederthal and its castle, Burg (Biederthal) – why are they separated by the border between France and Switzerland?
  3. Why does the canton of Solothurn (SO) “own” an exclave within Basel (BL)? What can the Burg Rotberg tell us about this?
  4. Why did the Romans dig a cart road (“Karrweg”) into the rocks to get from Flüh to Hofstetten – avoiding the valley? 
  5. The Chälegrabe above Hofstetten – why is this spectacular gorge called “Chäle”-Grabe”?

I have talked about secret #1 and #2. Now I continue with secrets #3 and #4 (leaving secret #5 for a later blog).


3  Why does the canton of Solothurn (SO) “own” an exclave within Basel (BL)? What can the castle Rotberg tell us about this?

The castle Burg Rotberg is beautifully located on the slopes below the Blauen chain, as seen from across, from the north, when walking from Mariastein to Metzerlen.

This is the view of the castle Burg Rotberg from “behind”; I took it, when walking at the foot of the Blauen. 

The castle Rotberg belonged to the noble Rotberg family that had their origins in this area. In 1408, the German emperor gave them the villages Rodersdorf, Metzerlen, Mariastein, Hofstetten, Flüh, Bättwil and Witterswil as a fief. The Rotberg family reported directly to the emperor, and the castle Rotberg was their domicile. However, soon the Rotberg family preferred to live in Basel, while their castle started to decay in the 15th century. 1451-1458, the family supplied the Prince-Bishop of Basel. His name was Arnold von Rotberg, and he is buried in the cathedral of Basel.

In 1515, the noblemen of Rotberg sold all the villages around their castle Burg Rotberg. They sold them to Solothurn for 4400 Gulden, and Basel advanced the money to Solothurn. It is true, for 4400 Gulden, Basel “gave away” the villages that were and are so close to their city. 

The castle Burg Rotberg was in ruins until 1934. At that time, it was reconstructed based on romantic ideas about “old” castles and opened up as a youth hostel that has been popular until today. 

Solothurn built its territory successfully from the 14th until the early 16th century. Some areas they conquered and others they bought. Their success in acquiring land at the cost of Basel becomes clear, when looking at the modern canton of Solothurn; it almost surrounds Baselland.


One of the villages now belonging to Solothurn, Mariastein, became an important place of pilgrimage. In 1648, the abbot of the Benedictine monastery at Beinwil decided to move to Mariastein. At Mariastein, he built the neo-gothic church with the baroque interior. The monastery was active until 1874, then closed down and reopened in 1941. The church and the monastery have been fully renovated after 1971. This is the view from the north, with the Blauen chain in the background.

I was surprised to find a vineyard here, above 500m. But, yes, I do understand, monasteries need wine for their Communion. 

There are many opportunities to pray around Mariastein – this is the Chapel St. Anna.

Across, from the south, the panoramic path at the foot of the Blauen chain provides the view of Mariastein with the castle Landskron in the background (the Landskron is already located in France).

Well, now we have learnt, just 4400 Gulden made the area of the Rotberg family become part of the canton Solothurn, of the canton that has been rivalling with Basel 500 years ago. 


Why did the Romans dig the cart road (“Karrweg”) into the rocks to get from Flüh to Hofstetten – avoiding the valley? 

When continuing my way along the foot of the Blauen chain towards Hofstetten, I enjoy the panorama; Hofstetten is located in the foreground; in the background we can see the city of Basel and the Black Forest.

The Flüebach valley leads from Hofstetten down to Flüh. First the Romans built the connecting road in the valley, but the Flüebach used to overflow its banks destroying the road again and again. To make the connection between Flüh and Hofstetten more reliable, the Romans decided to cut the road into the rocks above the valley. This Roman cart road (“Karrweg”) was in use until around 1800. 

It was the braking wheels of the carts that engraved the marks in the rock. The old Roman cart road is now the hiking path that I take to walk down to Flüh.

Flüh is attached to the cliffs. Actually around here, in the Jura and in the Pre-Alps, the cliffs are called “Fluh” or in dialect “Flue” (Plural: “Flühe” or in dialect “Flüe” or “Flie”). 

The community of Flüh-Hofstetten has published a charming Website illustrating the history with cartoons full of humour. An instructive pleasure to read through it.

By bike, I take the Napoleon route to return home, looking back at the village Flüh that climbs up from the valley towards Mariastein and the Blauen chain. 

I intend to return soon to explore the fifth secret, which is the Chälegrabe.

Around Basel: Historical secrets on the hike from Rodersdorf to Flüh

The area around Basel is full of secrets. 

Source: Swiss Mobile (with my notes added) 

In October 2020, I hiked from Rodersdorf to Flüh (red line), and discovered five secrets:

  1. Historical border stones from the years 1817, 1890 and 1951 between France and Switzerland – why from 1817? And can you see the “D” (Germany or “D”eutschland) hidden “behind” the “F” for France? 
  2. Biederthal and its castle, Burg (Biederthal) – why are they separated by the border between France and Switzerland?
  3. Why does the canton of Solothurn (SO) “own” an exclave within Basel (BL)? What can the Burg Rotberg tell us about this?
  4. Why did the Romans dig a cart road (“Karrweg”) into the rocks to get from Flüh to Hofstetten – avoiding the valley? 
  5. The Chälegrabe above Hofstetten – why is this spectacular gorge called “Chäle”-Grabe”?

In this blog, I will start with secrets #1 and #2, while leaving the other secrets for the next blogs.


1 The historical border stones between Metzerlen and Burg

Where the (car) road from Rodersdorf up to Metzerlen reaches the highest point of the pass, it touches the border between France and Switzerland.

The hiking signs to the Remel (or Raemel in French) are on the French side.  

Here we find stone #109 that is from 1890. It shows the edge of the French/Swiss border pointing to the wooden steps,…

… where the path lined with more historical border stones starts. The stones are either

  • from 1817 (just after the Congress of Vienna, 1815),
  • from 1890 (the Alsace belonged to Germany since 1870/71) or…
  • from 1951 (which happens to be my year of birth). 

After having climbed the wooden steps, we come across stone #110 from 1817. Why 1817? At the Congress of Vienna, in 1815, statesmen and diplomats had reorganized Europe, which needed to be documented.

All border stones from 1817 show the coat of arms of the Swiss canton Solothurn with S and O engraved to the sides.

On the French side, the French engraved the fleur de Lys. After 1870/71, the Germans, having conquered the Alsace, removed the flower to replace it with “D” for Germany. After World War I (1918), the Alsace became French again, and the French changed the  “D” into the “F” for France, but the “D” can still be seen (border stone #110). 

There must have been an inventory of the country borders in 1890. The Alsace was still part of Germany and Bismarck had just resigned. The 1890 stones have an “S” with a cross engraved on the Swiss side (stone #116).

The stones from 1951 have been produced more “efficiently”: A plain “S” and a plain “F” mark the countries (stone #115).

The pretty path with the border stones winds through the forest and crosses the romantic Y-shaped canyon of the Geissberg above Biederthal.

At Burg, we leave the canton Solothurn. We are now in the former Prince-Bishopric of Basel. 


2 Biederthal and its castle Burg (Biederthal) – why are they separated by the border between France and Switzerland?

In 1168, Friedrich Barbarossa, the one with the red beard, gave the area to the Habsburgians, as a fief. They built the castle or Burg Biederthal in 1250 to watch over their tithe courtyard Biederthal (Dinghof). In 1269, the archbishop of Basel bought just the castle/Burg of Biederthal, without its tithe courtyard Biederthal, which remained with the Habsburgians and later became part of France. This is why the country border separates the castle from “its” village. Burg now became a village of its own.

In 1946, Burg selected this coat of arms.

Source: wiki entry for Burg

Where does the coat of arms come from? The answer: The archbishop of Basel granted Burg as a fief to the noblemen von Wessenberg. They owned it from 1401 to 1793. Around Burg  we can find the historical border stones of the Wessenberg. One well-kept stone is a few meters below the summit “Remel/Raemel” above Burg. From the Wessenberg, the community of Burg took the coat of arms in 1946.

In 1815, the Congress of Vienna decided to merge the former Prince-Bishopric of Basel with Switzerland; Burg became part of the canton of Bern, belonging to the district Laufental. Later, in 1993, the Laufental (with Burg) voted to join the canton of Baselland instead. Nevertheless, many border stones around Burg have kept showing the coat of arms of Bern, the bear. This stone with the bear of Berne marks the border with France, just below Burg.

Border stones from 1817, 1890 and 1951 and a castle separated from “its” village by the border of France and Switzerland – yes, the area around Basel is full of secrets that can be discovered hiking.





Around Basel on a rainy day – in search of the Benkenspitz or Bänggeschpitz

Today it is a rainy and rather warm mid-February day in 2017. I set out to discover the Benkenspitz or “Bängeschpitz”. This is a narrow forest “wedge” of Benken (Switzerland) extending into France between the two French villages Hagenthal and Neuwiller (the border between Switzerland and France is drawn in pink on this Swissmobility map).


This “wedge” called “Benkenspitz” is some 900m long and some 100m wide. The narrowest place is at the “entrance” in the south – just 62m wide. In the Internet I found some secondary information that says this forest “wedge” has already belonged to Benken, when Basel acquired it in the early 16th century. It is assumed that this might have been a good place for hunting. Actually I came across quite a few hunting stands in this area both on the Swiss and on the French side.

My  blog “Around Basel – looking for old boundary stones on a sunny cold day” talks about my cold winter walk to the boundary stones between Oberwil (that until about 1800 belonged to the Bishopric of Basel) and Benken (that – with Biel – had been acquired by the town Basel soon after 1500). Today it is rather warm and rainy. The Passwang is still covered with snow.


I am on the Bielhübel in front of the water reservoir with its natural pond.


Not far from here are the beautifully restored boundary stones from the 17th and 18th century that mark the border between Oberwil (Bishopric of Basel) and Biel-Benken (belonging to Basel).


I continue my way above Biel and come across a lady on a very, very dirty mountain bike. “Have you seen anyone on a mountain bike – I have lost my husband… no?… “Matthias, Matthiaaaas”… I do not want to frighten the animals, there is so much deer around here… I am from Spain… Matthiaaaas, Matthiaaaaaaass…” and finally Matthias replies and she is happy. “You are looking for boundary stones?… there is one not far from here…”, she says knowing well the history of Biel-Benken. Right, here it is, shortly before reaching the Swiss hiking path marked in green at the Swiss-French border.


From here I continue along the Swiss-French border between Neuwiller and Biel-Benken. A small footpath follows the boundary stones, marked with the Swiss cross on one side…


… and with the “F” for France on the other side (1816 – this was just after the Congress of Vienna in 1815).


Later this well prepared hiking path ends and continues as a muddy path. EXACTLY where the nice path ends and the mud begins is – guess what – the border between France and Switzerland.


I cross this road to continue following the boundary stones. I meet a lady with two dogs. She comes from Neuwiller in France and takes out dogs of various owners. We speak French with one another while one of the dogs barks loudly at me – with a French accent.


After having paved my way through a muddy meadow, I cross the road connecting Benken with Neuwiller. Again, it is very clear, where the border is. Baselland (Basle Country), the canton of cherry trees, says good-bye to the cars crossing the border and driving to Neuwiller in France.


I cross the road and follow the ditch that is the border between Switzerland and France. This one boundary stone is nicely coloured on the Swiss side.


Still following the ditch I approach the “entrance” of the Benkenspitz. It starts on the meadow between the two forests.


I first see the boundary stone to the west of the “entrance”. I am confused, but then I find the stone marking the east of the “entrance” to the forest “wedge” and enjoy the view of the Jura hills in Switzerland.


I continue along the east line – one boundary stone after the next to make it all clear, where Switzerland ends in this narrow wedge and where France starts.


A huge tractor cuts trees – in France. I  have reached the end of the Swiss wedge called “Benkenspitz” and return back along the west border – again well  marked.


I leave the Benkenspitz behind me and continue to follow the French-Swiss border. This is an interesting cooperation: A Swiss traffic sign (only residents are allowed to drive here) and a French hiking sign of the Club Vosgien.


And – across of this French-Swiss cooperation – be aware, following this hiking sign takes you to France, only allowed when having nothing to declare!


Along vineyards the boundary stones lead me down towards Benken.


I take the bus back to Bottmingen – good that public transportation works so efficiently.

So much to discover around Basel – the Klus and the Burgengratweg

The Klus west of Aesch near Basel – wine and culture

West of Aesch near Basel there is a small valley with southward looking slopes that have a tradition of wine growing – it is the largest wine growing area around Basel. On the hills around the Klus valley there is culture – a dolmen tomb, an old cave and various castles (all ruins). The ruins south of the Klus valley are connected by the marked “Burgengratweg” (“ruin ridge path”), and there is another ruin north of the upper Klus, Frohberg, that is more difficult to reach out to.

aesch w pfeffingen

I like the Klus and check out the marked hiking paths and the more hidden unmarked paths to get ready to lead the Monday Nordic Walking group to the tomb and the castles. Thank you, Andreas and Helga, for uncovering the secrets of this valley to me.


The Dolmen tomb 

I start my walk above the vineyards in the forest following the yellow hiking signposts. A brown plate directs me to the dolmen tomb.


Only the basis of the tomb is left and protected by a fence. Originally it has been covered with stone slabs and must have been some 2-2.5m high. It has been built around 2500-1500 BC (late stone age or bronze age).


Nearby I have a wonderful view of the Klus vineyards and the forest hiding the ruins along the “Burgengratweg”. The Gempenplateau can be discerned in the background.



Looking for the ruins defending the Klus

A narrow path takes me up to the ruin Frohberg that is well protected sitting on the top of an almost inaccessable rock. The castle has not been explored by archaeologists. They assume that it has been built by the Schaler family in the 13th century, perhaps as an additional stronghold against the family Münch that also owned a castle overlooking the Klus valley. Like most castles around Basel it has been destroyed in the 1356 earthquake and may not have been reconstructed. Later the bishop of Basel owned Frohberg with the farm Tschöpperli/Tschäpperli and gave it to the family Thierstein as a fief. They managed the farm from the nearby castle Pfeffingen.


Today, the Tschäpperli farm is one of the renowned wine growers of the Klus.


These are some of their vineyards.



A short round hike on unmarked paths makes me discover the lama farm

I walk towards the Blattenpass and turn left on an unmarked path to cross the Bielgraben (“Biel ditch”). A beautiful panorama view of the Tschäpperli vineyards and a charming path under birch trees…


… take me to this sign announcing llama xing. Llama xing – here in Switzerland! Yes, the farm “Obere Klus” has lamas – among other animals. The lamas are rented out for hikes.



The narrow and sometimes exposed Burgengratweg (ruin ridge path)

About 50m down the valley I enter the Burgengratweg. There is warning: The path is not in good state, you go there on your own risk. Well, it is narrow, stony, with roots – pretty rough for standards around Basel, but there are more dangerous hiking paths in Switzerland. Each of the sights I will come across on the Burgengratweg has a plate that explains the history.


After having crossed a small creek, I reach the Schalberghöhle (Schalberg cave). Flint stone tools and animal bones from 50’000 years ago  (“Moustérien” ) and from the late stone – and bronze age (about 3500BC and 1000 BC) have been found here.


The first castle is Schalberg, built by the family Schaler (they have also built Frohberg). After the earthquake they rebuilt this castle. They later sold it to the bishop of Basel (1437) who gave it to the Thierstein family as a fief. Soon thereafter the castle must have been abandoned, as it is no longer mentioned in the archives.


Also the second castle, Engenstein, belonged to the family Schaler. The castle was also called “Alt-” or “Vorder”-Schalberg. A dizzying iron ladder leads to a platform. It has been given up already in 1280, probably, because the family had built the “newer” Schalberg castle not far from here.


The next castle, Münchsberg, built in the 13th century, belonged to the family Münch that later also sold the castle (with farms) to the bishop of Basel and received it back as a fief.


The last castle on the Burgengratweg is Peffingen above Aesch and the namesake village Pfeffingen. Its origins go back to the 11th century. In the 12th century, the family Thierstein owned Pfeffingen (along with nearby Dorneck). From 1522 it belonged to the bishop of Basel; his bailey then lived here. In the late 18th century the castle was abandoned. It is currently being renovated.

As it starts to pour with rain, I leave the forest and the narrow, now slippery ruin ridge path.


Strolling through the vineyards and discovering innovative wine growers

In the rain I prefer to stroll through the vineyards. There is a round tour with posts explaining the business of wine growing throughout the year.


Monika Fanti is a winegrower that also runs a small restaurant (“Winzerbaizli” or “little winery pub”). I like the names of her wines: “ilFANTIno”, “exKLUSivo”, “FANTIssimo” and “mySEELEdröpfli” (literally translated: “my soul droplet”). I take a leaflet with me announcing “Neus vo eus”, meaning “news from us” in the dialect of Basle Country.


I plan to get back to this place. Some of the wines of Monika Fanti would be a great addition to my gift drawer – besides, of course, trying them out myself.

A few meters higher up I find “chez Mitz”, where I can hear laughing through one of the open windows – I think a Sunday brunch is going on. Teddy bears sit on the window sills looking down at the hikers.

Really, the Klus of Aesch is a charming corner! I look forward to the Monday walk with the group and I will surely come back more often.

So much to discover around Basel – Pratteln

My new mountain bike takes me to Pratteln and I discover who has been here before…

This year – 2015 – I bought a new mountain bike. I set out to explore more of the secrets around Basel to plan the nordic walking hikes that I am now guiding – with my eyes restored. My next target is Pratteln. This small town has published the excellent and very detailed “Heimatkunde Pratteln 2003” (Emmy Honnegger et alii) and a nice Website. I pick a few cherries that might add to the walking experience around Pratteln – I love to know more about the places that I am hiking to. And – any misinterpretations are my own fault – I am not a historian.

Karten Pratteln

Source: Bundesamt für Landestopographie 213T – Basel


Pratteln – why are you called “Pratteln”? Ah, you were a “small meadow” near Roman Augusta Raurica

The name “Pratteln” comes from the Latin “Prattelum”=small meadow. Pratellum was a suburban service center for the Roman town Augusta Raurica, with farms and crafts business. It seems that, after the Roman empire had collapsed, the Alemanni did not settle here before the 7th/8th century, and the population continued to speak a Roman language. If the Alemanni had settled here earlier, the alemannic second sound shift would have transformed “Pratteln”  to”Pfratzelen” (“Heimatkunde”) or “Pfrasseln” (wikipedia). I prefer “Pratteln”  to “Pfratzelen” or “Pfrasseln”. We Swiss just say “Braddele”.

The large farms surrounding Pratteln today indicate that it must have been a beautiful service center for Augusta Raurica. Here is Mayenfels above Pratteln that is now a school.



There were settlements in Pratteln long before the Roman times – perhaps

To the south of Pratteln there is the “Hohle Gasse” – a very steep and even today mostly unpaved path that connects Pratteln with the “Chäppeli”.


It was here that a school boy found a hand ax in 1974. The ax is older than any other ax found in Switzerland – the estimates I could find reach from 120’000 to 350’000 years (sources: “Heimatkunde”, p. 71 and Website of Kanton Basellandschaft). It is not clear, whether the glacier has transported the ax to this place or whether the owner really lived around Pratteln. Too long ago to know for sure.

Signs of settlements from stone, bronze and iron age have also been found around Pratteln (see Heimatkunde p. 72).


Medieval times: Monasteries and the noble family of Eptingen. Later owned by protestant Basel

Until around 900 AD the monastery of Murbach (Alsace) had possessions in Pratteln. Reminiscence today: The church of Pratteln is dedicated to Murbach’s patron, Saint Leodegar. The church was later sourrounded by a wall to protect it against the floods of the Talbach (Heimatkunde, p. 97, the wall is called “Kirchenbering”).


Other reminiscences of those early days  can be found in the field names. For instance starting around 700 AD, forest areas were cleared to gain space for agriculture. These areas were then named Blözen (related with “entblössen”=to bare), Rüti (medieval German “ruiten”=to clear) or Stockmatt (when the thick roots (“Stock”) remained in the meadow (“Matt”)). Other names describe the topology: “Halden” is less steep than a “Rain” (Moderhalden and Blözenrain). “Goleten” points to a landslide that left stone blocks (My Ernst also said “Golete”). In the “Cholholz” – there was a charcoal burning site (Heimatkunde, p. 25f).

In the late 11th century the monastery of St. Alban, just east of the city  gates of Basel, was given possessions in Pratteln. St. Albanstrasse and St. Albanmatte in Pratteln remind us of this today.

In the late 13th century the noble family Eptinger settled in Pratteln (presumably it was a feud from Habsburg).  In the 13th century, they built two castles, one in Pratteln in the valley (surrounded by water) and a second one on the Madeln hill above Pratteln. After the 1356 earthquake, they rebuilt the castle in the valley. Owned by the government since 1773, it is no longer a water castle today, has been beautifully renovated in the 1960’s (see Ernst Zeugin) and is open for the public (guided tours).


The castle on the Madeln hill (Madlechöpfli) has not been rebuilt after the earthquake. Today only the ditches can be distinguished on the hill, the remains of the ruins have been covered up in the 1930’s to protect them from further decay. No spectacular ruins for today’s hikers on the Madeln summit – just another picknick spot in the dense forest. But, when having a picknick on Madeln, beware of the Madlejäger or hunter of Madeln. He comes with twelve white dogs, when the weather is changing. He has suffered until these days, because he had killed the owner of Schauenburg to marry the widow (Heimatkunde, p. 318). Below, the “bosky” highest point on the mountain range in the background is the Madeln hill.


In the 15th century, Hans Bernhard von Eptingen built the monastery of Schauenburg and a chapel with a hospice in the Geisswald just above Pratteln. The place is called “Chäppeli” which reminds us of Hans’ chapel that does no longer exist – after the reformation (1529) the stones have been reused to build the parochial house of Pratteln. The fountain is said to give curative water and the Geisswald seems to be an energy spot emitting 8000 Bovis (“Geiss” pointing to what we call Kraftort in German). This was a good place for a chapel and now it is a good place for a vast picknick and play ground. The foto shows the area with the fountain in the background.


In 1521 the family Eptinger sold the castle and part of Pratteln to Basel – for 5000 Gulden. 1549 the Habsburgians gave up the rest for 3000 Gulden. However, with their coat of arms – an eagle with  red tongue and red claws –  the noble family Eptinger is omnipresent today, on banners, on the cars of the firebrigade, in gardens… everywhere. To differentiate their banner from the emblem of Eptingen (also a former possession of the Eptinger family), Pratteln has added a black frame.

I found the emblem on the little hut at the picknick spot “Chäppeli”.


and everywhere in the center of Pratteln  that today, July 31st, is preapring for the Swiss national holiday on 1st of August.



Modern times – salt and industrialization… and taking care of the medieval village center

In the early 19th century salt was found near Pratteln. This started the industrial development.

Based on a geological map, Peter Merian forecasted the chance of finding salt on the shores of the Rhine. Carl Christian Friedrich Glenck dug, found salt in 1836 (116m under the ground) and a year later, he opened the first saline factory. Now the Swiss Rhine Salines produce 450’000 tons of salt a year in the valley and on the adjacent hills of the Plateau Jura, south of Pratteln and Muttenz.

The presence of salt as an important component attracted chemical factories. From the motorway, I have always seen the signs of the “Säurefabrik” (“acid factory”) – now I know, the Säurefabrik came here in 1918 to combine salt with iron sulfur which results in salt – and sulfur acid (Heimatkunde, p. 107). And Ciba, Novartis, Sandoz and many more national and international enterprises form the industrial complex of Schweizerhalle between the railway and the Rhine river today – this sight is taken from Google Earth.

Schwei$zerhalle Google Earth

Source: Google Earth

Despite the industrial evolution, Pratteln kept its charming historical center and makes it worth a visit.



Vineyards – first mentioned in 1284 and a pastor from the 17th century that must have loved the wine…

There are vineyards to the south of Pratteln. They were mentioned first in the books of the monastery of St. Alban in 1284. The production was then around 60’000 liters. In 1749 a historian praised the vines of Pratteln, “in particular the red wines are among the good and dense wines of our region (gut und kräftig).” (Heimatkunde, p. 170). In 1807 there were 47ha of vineyards (in the valley and on the hills). Now just about 6.7 ha are left, all on the eastward looking slopes of the Ebnet (see Weinbauverein Pratteln). There are two professional and  20 hobby wine growers producing about 60’000 bottles a year.


One of the two professional wine growers runs the Leuengrund. It has a small restaurant (open from October to February; this is a Straussen- or Meienwirtschaft, announced by a bunch of flowers, a custom based on Charlemagne (768-814)). Find below the Leuengrund with its gorgeous view. I will come back here in autumn, when the restaurant is open.


In the 17th century, the pastor Christoph Hagenbach (1596-1668) had a small half-timbered house built on the edge of the vineyards, overlooking the Rhine valley with the Black Forest and the Vosges. It was here that he prepared his sermons (perhaps the wine helped him find the right words). After him, this wonderful spot is called “Hagebächli”. Look at his cosy little house…


…  and the view over Pratteln to the Dinkelberg beyond the Rhine river and the Vosges in the background to the left.



Well, I am impressed by the history of Pratteln. I love to share it with the nordic walking group, when hiking here. Andreas and Helga, thank you for having opened my eyes for the secrets of my home region around Basel.

So much to discover around Basel (the Hardwald with water supply and Roman watch tower as well as an idyllic restaurant)

Andreas and Helga love the idyllic restaurant “Gasthof Solbad” just bordering on the Rhine

In the summer, the Gastof Solbad opens their garden bordering the Rhine. It is a great setting under a weeping willow. On a sunny day in June 2015, Andreas and Helga take their Nordic walking group to this idyllic place.



Our walk through the Hard and along the river Rhine (Rhein)

To get to the restaurant Solbad in Schweizerhalle, we have to cross the Hard. “Hard” actually means “forest”. We start in “Neue Welt”, walk along the river Birs, climb up to the Hard, oscillate a bit to make enough kilometers (10 to 15km) and then take the “Rheinpfad” that leads along the Rhine with posts of interest on the way. The restaurant Solbad is in Schweizerhalle.

Karte Hard

Source: Karte Schweizmobil


The Hard – a paradise for walkers and indispensable water supply for Basel

The Hard supplies water to Basel.

As this panel says, water from the Rhine becomes pristine water (from the Rhine=Rhein, made pristine=”rein” – a game of words in German).  Rhine water is pumped up and then purified in filters.


The purified Rhine water is directed to water channels with gravel beds. It sinks to the ground and adds to the Hard groundwater. The clean water from the river and the ground is then transfered from the Hard to the Langen Erlen north of Basel that also has its own groundwater. From there it is provided to the town.


These water channels are part of the purification system in the Hard. They add to the romantic atmosphere that walkers find here.


There is a control system to feed the water channels.


Wooden bridges allow to cross the water channels. We make a loop following the water channels and then leave this area to continue along the Rhine.



Along the Rhine: The Romans were here – and left their marks

This late Romanic watch tower borders the Rhine. It was built in the late 4th century, when the Romans came more and more under pressure by the Germanic and Alemannic tribes. Just the stone basement is left and has been preserved in 1975.



Dismantling of a huge industrial building in Schweizerhalle

Not far from the watch tower – when still walking in the woods – we hear a terribly loud noise. When leaving the woods, we see this huge industrial building that is now it being dismantled piece by piece. When walking by, we almost have to protect our ears.



Navigation driven by muscles

Our last place interest is the “Schiffahrt mit Muskelantrieb” or “navigation driven by muscles” (named “Rothus” on the map).


These are the boats that are driven by muscles – we call them “Weidling” which is similar to a “punt”, as Wikipedia says.


Soon after this boats place we reach the garden of the restaurant Solbad and order a drink to cool down.

Thank you, Andreas and Helga, for having showed me some more secrets of Basel region. From the restaurant Solbad I walked back home the same way to enjoy it once more and take the fotos using my iPhone. I look forward to more treasure hunting with you.