27 February, 2009

A face carved into a tree...

I'm in the field again. Yesterday was consumed by an organisational talk in the office in Freiburg and shopping to fill the refrigerator with food stuffs. Today was the first day in mapping again. Nothing spectacular in terms of geology but again I found a face! Little words here it is...

22 February, 2009

A Jurassic omission surface within the Hauptrogenstein-Formation

Before I leave for fieldwork a quick post about an easy to recognise omission or discontinuity surface.

The lower, massive layer in the fotos below is the "Oberer Hauptrogenstein s. str." and the upper layer are the "Movelier-Schichten". Both part of the Middle Jurassic "Hauptrogenstein Formation" in the foothill zone of the Upper Rhine Graben. The omission surface is apparent by the sharp contrast of lithology between the two layers. Ooid-Grainstones at the bottom, Bioclastic Float-Rudstones on the top. The omission surface itselfs is characterised by an undulating surface, partially iron-stained, with small pits and holes that can be interpreted as paleokarst that developed on an exposed hardground. Heim (1924/34) first used the term omission surface to designate a depositional hiatus and discontinuity surface of minor form.

Outcrop foto of omission suface on top of the "Oberer Hauptrogenstein s. str." (top 1.20 m exposed on foto)

Hammer stuck in the omission surface. Beds show secondary karst.

21 February, 2009

Fieldwork is calling

Monday I will be leaving again for fieldwork. If the weather holds I should be able to complete mapping for my diploma mapping project this time. The outlook dispite the recent strong snow looks good at least in the region where I will be working. I'll be staying in the same location (that has internet access) so I probably can occasionally keep you informed about what I am doing and post some fotos of fieldwork. I'll be away for a good month.

17 February, 2009

A fault next to a fault next to a fault...

Trying to motivate myself (not working, yet) I'll let you get a feel of something scary. The image is a drawing of the fault tectonics on the French side of the Upper Rhine Graben foothill zone. Basicly on the opposite side looking from where I work. My part is just like that. Faults everywhere. Wohoho!

Image taken from Illies (1977)

Take a loot at the scale and keep in mind: only big faults are included.

15 February, 2009

Lost Geologist's art

Please apologise for the recent silence here on the Lost Geologist. My diploma mapping report is keeping me occupied as I am trying to advance it wherever I can before returning to fieldwork at the end of this month. Writing serious stuff pretty much drains my creativity for other matters, i.e. coming-up with good blog posts. Although I do have one or two not entirely thought-through ideas spooking around in my head. Well, we will see what develops out of them. For now I like to share two pieces of art. The first another rather abstract painting I made some time ago. Not necessarily my best I believe. The other piece is a drawing I made in 2005 of some beautifully exposed folds on the French coast in Brittany. If you are interested the location is given on the drawing itself, including coordinates. I made it during one of the best field trips of university. Brittany was really cool. Mapping directly at the seaside.

Two very different pieces of art that can originate from the hands of a geologist. Allbeit a few years apart from each other.

09 February, 2009

Book recommendation: Carbonate Sedimentology

You will easily notice when following my blog that I am working a lot with carbonates these days. That interest developed in the last year or two and was further advanced when I had the chance to attend two very entertaining presentations by Maurice E. Tucker during the XIII Latin-American and XIV Peruvian Geological Congress in 2008 that also gave me the, sadly enough, rather short possibility to meet Maurice Tucker and shake hands.

The book Carbonate Sedimentology by Maurice E. Tucker and V. Paul Wright I already liked before that event but I decided to actually get it myself then right after I was back home. Allthough written and first published in 1990 I still consider it one of the best textbooks on carbonate sedimentology that are available. Even if you have little to know knowledge on carbonates it will guide you in 9 very readable chapters from the basics and building blocks of carbonates, the sedimentological principles behind them, modern carbonate environments, depositional systems, their mineralogy and chemistry, diagenesis and dolomites to carbonate systems in the geological record. The book is augmented by many good illustrations and profits a lot from the enjoyable writing style of the authors. Both students and professionals who haven't worked with carbonates before will find something for them in this book. Without going too much into microfacies analysis it presents and explaines carbonates in easy to understand terms. The only downsides I found are the often too dark fotographs that make recognition of the objects shown not always easy and the paperback format. The book itself will easily suffer from active usage. I assume that is due to the re-print quality. Dispite that I can whole-heartedly recommend the book! It is not easy to come-by at least in Germany and I had to wait 5 weeks after ordering it. Well, it was worth it. For all those not wanting to invest too much money you can surely find it in any good geological library.

Carbonate Sedimentology Front Cover

07 February, 2009

Aren't they cute?

I like cute animals. These I found during work in december. While going through my fotos I saw them again. They live in a small kind of zoo. Thought I share. The little one is very young I think.

Little one

I think this is daddy.


Cute, no?

03 February, 2009


During field work one may encounter a lot of fascinating things (i.e. flying deer - but that's a weird anecdote for later). More of a geological context can be observed in the below foto. Wonderful, wonderful stylolites! They are plentiful where I work but these where the best ones to capture right there in the wild. Dirty fingers for scale...

There has been some debate over how exactly stylolites form which I would recommend you to read in the available literature. I think we can all agree that they represent some form of pressure solution related to diagenesis of limestone rock. They are usually absent in limestones containing more than 5 to 10% clay. So plenty of stylolites are a good first indication that you are looking at a pretty pure limestone. They will cross-cut any kind of rock fabric without discrimination. Nevertheless when working in limestones you may find horizons that are preferably transected by stylolites. There is sufficient indication that early cementation is respondsible for this phenomena. Early cementation protected grains from mechanical and chemical compaction. So it may also be a hint for episodic cementation. It is hard to tell how much rock has undergone solution though. Dispite that I think it is safe to say that it was at least the same amount as the amplitude of the stylolites. Probably a lot more.

The dark color of most stylolites is caused by the accumulation of insoluble substances. Clay and iron oxides from the dissolved limestones will be concentrated. Stylolites often represent barriers to permeability. Something you should keep in mind especially when interested in petroleum production. Nevertheless there are examples where stylolites can act as important porosity and conduits for fluid migration.

Having said that: Perhaps I should scrap-off some of the dirt of some stylolites and have it analysed?

If you want to know more: Carbonate Sedimentology by Tucker & Wright (1990) has a short but good summary.

Archaeological WoGE

Recently I got a few visits from Electric Archaeology that allowed me to discover that the archaeologists have discovered and modified Where on Google Earth to When on Google Earth. The 2nd run is currently taking place on AWOL. So dispite the hiatus in our WoGE game it seems that it is not dead at all! Perhaps dare we call it evolution and adaptation instead?!

BTW: Ron solved WoGE #155 after a several months long delay. Check out this site for further news.