'Not all students knew what yardangs were and there was some confusion with rock pedestals and zeugen'
You may wonder why I am so obsessed with zeugen, after all, they're just some rocks in a desert... I suppose I do have a somewhat obsessive personality when it comes to teaching (which perhaps explains why I spent so many hours planning lessons!) but it's important to get things right, especially when it's for someone's exam, and hence their future!
I came across the zeugen when I first started teaching deserts and this landform caused me many hours of grief as, in my determination to cater for visual learners and provide a link between theory and reality I tried to find a picture of one to show my students, just like I do with any landform. Although the Philip Allan AS textbook clearly states what a zeuge is and has a diagram of one, it doesn't have a photo.
I tried searching for the word online but all 'Professor Google' can come up with are mesas, buttes, yardangs and, much to my irritation, rock pedestals (aka mushroom rocks), useless! As I researched further I discovered that I was not the only one who wasn't sure what they were, even the exam board who wrote the specification couldn't seem to give me a clear answer! Even worse, when the new Oxford textbook came out it had a picture of a rock pedestal and underneath labelled it as a zeuge! I was beginning to wonder if AQA and the textbook I had had got it wrong, and that 'Zeugen' and 'Rock Pedestal' were simply 2 different names for the same thing! But then, since it was in the AQA spec. I had to go with it and teach them as 2 separate landforms, even if was wrong I had my student's grades to think about! I simply used a diagram to show them what a zeuge looked like and fortunately none of them questioned it.
The page below reiterates what the Philip Allan textbook says and gives a very good explanation of a Zeuge and how it differs from a Yardang, however, notice there is no photo.
I wasn't happy about this lack of evidence that these things really do exist (obsessive teacher alert!) so recently, while I had some time on maternity leave, I decided to look into it again. This time I did find this very useful page which gave further diagrams and confirmed that zeugen are indeed a separate landform, examples of which can be found in the deserts of Bahrain! This got me very excited as I had the name of the a place where they were! Perhaps they were real after all and I was finally going to see a real picture of one. All it took was a quick image search of 'Bahrain Desert' and voilà! I found these images, they do exist! woohoo!! (that is if these things are actually zeugen..., I'm going to assume they are unless someone else can enlighten me??).
ZEUGEN IN BAHRAIN (source)
ANOTHER ZEUGE (source) - see some more great pics here too
So, there you have it. Rock Pedestals, Yardangs and Zeugen, 3 different landforms!! With similarities, but also distinct differences. Please don't get them confused again! Right, think I might write to Oxford and let them know that their textbook has a mistake in it!
Ok so it turns out 'Zeugen' is a German word meaning 'witnesses' (hence 'Zeugen Jehovas') and since it's a plural word I've been using it wrongly, it should be 'a Zeuge' and 'several Zeugen' - so apologies for this (now updated!). I discovered this whilst reading FJ Monkhouse's Dictionary of Geography (London, 1965) which was given to me by our college library as it was so old they decided not to keep it anymore. I love old books and have been reading through all the interesting definitions; then I thought of looking up Zeugen:
"Zeuge (pl. zeugen) (Germ) A tabular mass of resistant rock up to 100ft high, standing out from softer underlying rocks because of its protective capping. It is produced by differential erosion in a desert through the scouring effect of sand-laden winds."
Underneath it has a labelled sketch of 3 rock pedestals.
Similarly I found this in a 'Glossary of Geology' published in the US in 2005:
"Zeuge - a tabular mass of resistant rock left standing on a pedestal of softer rocks, resulting from differential erosion by the scouring effect of windblown sand in a desert region; it may be 2-50m high. Cf. mushroom rock; Syn. witness rock."
Since it's a US publisher while the other book is British, I assume this confusion in terminology can't be put down to a difference between the UK and US (as with the issue of whether crystal growth is a form of chemical or physical weathering).
Further use of Google reveals this definition by David Lambert from The (2006) Field Guide to Geology:
'Zeugen are parallel, flat-topped ridges of hard rock up to 100ft (30m) high'
This is accompanied by a diagram very similar to the one I have pasted above, showing joints widening until just the ridges are left behind, protected by their resistant caps. But they are definitely long; and not rock pedestals, which are defined separately on the same page as:
'Mushroom-shaped rocks, often made of horizontal layers'.
So, what is going on? I have an urge to visit the Foyle Reading Room and solve the issue once and for all, but sadly I live far from it so it will have to wait. Perhaps I can shed some light on the issue during the GA Conference next week....!
Far from solving the issue the GA conference last year proved to be a source of even further confusion with one geologist telling me, when I showed him a picture of what I thought was a rock pedestal, that it was a yardang!
I did recently attend an A2 revision conference however, and met the very helpful Phillip Banks who informed me that, in his opinion a zeuge and a rock pedestal are different types of the same thing - the first being an elongated landform, the second simply having become isolated after further erosion, similar to a protruding cliff eventually becoming a stack I suppose. So technically a rock pedestal IS a zeuge. This makes a lot more sense to me given the meaning of the word. However, it seems that AQA would prefer us to distinguish between them, so I'm going to go with:
Yardang - elongated rock formation comprising vertical layers of alternately hard and soft rock
Zeuge - elongated rock formation comprising horizontal layers of alternately hard and soft rock
Rock-pedestal - a type of isolated zeuge; a mushroom-shaped rock that is undercut at the base
I'm going to assume that a zeuge becomes a rock pedestal once the length of the feature becomes the same as its width. And that in an area where the rock strata are aligned neither horizontally nor vertically but as an angle of exactly 45o the feature is called a Zeudang...
Personally, after all this I am somewhat disillusioned by giving all these landforms names in the first place, especially when 99% of them don't look anything like in the textbook. Rather than attempting to classify differently shaped bits of rock into different categories surely it is better to focus on the processes that formed them and recognise the complexity and continuity of the physical landscape?