World heritage !

The Dolomites on Friday 26.06.2009 were accepted to enter the list of the UNESCO World’s heritage, not only for their natural, but also cultural importance.

The Dolomites played and play a central role for the history of geology and paleontology.

The stratigraphic succession of the Schlern mountain in a book of general geology of 1907.

The area of the Dolomites in the Southern Alps has attracted geologists since the early 19th Century, the vast outcrops and the sudden change of different lithologies – and so sedimentation conditions – was an ideal field for studying sedimentological and also tectonic questions. One of the most important achievements’ was the recognition that the outstanding carbonatic peaks and mountain groups are remains of ancient carbonate platforms and coral reefs. In early days of geology less was known about sedimentation in oceans, only selective probing was possible by dragging samples of the bottom of the sea, and so only in 1842 Darwin formulated a first hypothesis on atoll formation. Influenced by this model, intensive field mapping was carried out, and in 1860 the German geologist Ferdinand von Richthofen (1833-1905) recognised as first the organic origin of the carbonate rocks of the Schlern, in the valley of Fleims and Fassa. In the work of Johann August Edmund von Mojsisovics (1839-1907) “Die Dolomitriffe von Südtirol und Venetien” (1879), where he described the stratigraphic succession of the reef built-up and basin succession, the research on old reefs gave back important impulses to the interpretation of modern reefs.

In Leopold von Buch´s work "Esquisse d´une carte geologique de la parte meridionale du Tyrol" (1822) the author distinguishes carbonatic from dolomitic rocks.

In the map of Edmund Mojsisovics (1878) he distinguishes different formations by various different colors.

The outcrops in the Dolomites also helped to clarify an ongoing quarrel between geologist, proponents of the Plutonism, and geologist, proponents of Neptunism. The questions were if all know rocks have either a pure volcanic origin, or were deposited in an aquatic milieu.
The Italian mining engineer Conte Giuseppe Marzari-Pencati observed in 1806 in the valley of Fassa that granite covered carbonates, so the first has to be originated later. An impossibility for the scientific hypothesis of Neptunism of that time.

Sketch of the outcrop with granitic rocks protruding in calcareous rocks by Marzari-Pencati (1849).

Ecce Homo!

The site of Bilzingsleben is located on the northern bordere of the Thruringian basin, today on a small mound in the middle of pastures, fields and villages.
370.000 years ago in contrast it was the bottom of a valley with springs located on the border of the slopes, feeding creeks that flowed in a lake. Only thousand of years of erosion have switched the topography, eroding softer rocks and letting over only hard lithologies, like the calcareous tufas that remain from this past world.

Fossils of the interglacial period of the Holsteinian can found principally in tufa sands, deposited originally on an alluvial fan and the shore of the ancient lake. This deposition is extremely rich on bones of mammals, and as distinctive feature skull fragments, teeth’s and stone tools of Homo erectus.

The incredible concentration of bones seduced some authors to interpret this site as hunt and butcher-place of the early man. They also saw in the accumulation of stones and bones signs of “fundaments” of huts – at least three of them. But this interpretation is not widely accepted, new excavations and observations on the site showed that the “fundaments” and the “flagged floor” are distributed in a range of 1m of the geologic column, not on a single horizon. Also the position of bones, attribute to human butchering, is straight north-south trending, a clue that provides more for fluvial, rather than anthropogenic induced orientation.

This reinterpretation has maybe also important repercussions on the theory of early man as great hunter, forcing the pleistocene megafauna to extinction.

Silex - artefact from the site of Ehringsdorf (ca. 200.000y) by (presumably by Homo neanderthalensis), showing that central Europe was inhabitat by man for more then 400.000 years.

Algas Rocks!

Spring tufa forms by precipitation of calcium carbonate from supersaturated waters. Supersaturation is mostly attained, or is highest in some distance downstream the emergence of the spring or within streams in areas of rapids or water falls. The most important factor for tufa formation is degassing of carbon dioxide, so the water reaches the necessary degree of supersaturation for precipitation of calcium carbonate. Degassing can be achieved by physical processes, like highly turbulent flowing water, or biological processes, by presence of vegetation or microorganisms.

Riffle-pool sequence, the water flows fast and loosing his dissolved carbonate deposits tufa layers, the calcification of organic debris is very strong.

Rivularia sp. encrusting a tufa coated boulder.

Plants or autotrophic organisms, especially very small ones, like algae, can influence the hydrochemistry by changing the amount of dissolved carbon dioxide by their metabolism.

Also secreted extracellular substances, for example by Cyanobacteria, common in creeks and ponds, can profoundly modify the shape of crystallized calcium carbonate. Microbial induced tufa is widespread and can comprise the major part of total carbonate volume found in the surroundings of a spring.

Near “Teufelskanzel” – a small spring in a carbonatic catchement examined in 2006 - especially on the rock wall rigth of two small waterfalls modern tufa precipitation takes place. On the left side of the waterfall the scarp is overgrown by the moss species Eucladium verticillatum and Cratoneuretum sp., in contrast on the rigth part of the scarp, an algae mat was established.


In Tab.1 the found algae are listed following a transsect that stretches from the vicinity of the waterfall to the distant, respectively from to wet to dry: Locations 1 and 2 are located directly under the waterfalls, number 3 is influenced by spume of the waterfall and number 4 is already dry. Under wet conditions Phormidium incrustans and P. autumnale were quite common. In sample 2 Leptolyngbia perforans was recognised, in the green layer, incrusting the moss tufa. Also Chamaesiphon rostafinski was found attached to a Pseudoscytonema.


The observed algae mats, growing on 1,5 – 2,5 mm thick tufa layers are approximately 1000 μm thick layers, composed of Scytonema sp., Petalonema sp. and Crooccocales, including rhombohedral shaped cristales. The aerophilic Gloeocapsa rupestris and also Nostoc sp. were found under dry conditions in the algal mat.


In microscopic mounts of the algae mat, two types of cristal structures were observed in contact/related to the algae species Scytonema sp.:

(1) Rhombohedric (euhedral = with cristal faces) single cristals. Some of them are rounded, likely by chemical and mechanical erosion. In many cristaly wholes were observed, which may resemble with imprints of algal filamtents. Thus it can be supposed, that the nucleation of the cristal grain starts at the algal filament.
(2) As a second observed type, consistet of aggregate of cristals, that grew radially around the ending of some filaments.


This first observations shows that algae can play an important role for the nucleation and growth of cristal growth and so for tufa formation.

References:

SANDERS, D.; UNTERWURZACHER, M. & RÜF, B. (2006): Microbially induced calcium carbonate in tufas of the western Eastern Alps: a first overview. Geo.Alp, Vol.3: 167-189

SCHLETTERER, M.; PERNEGGER, L. & BRESSAN, D. (2006): Tuff production at the "Teufelskanzel", Mühlauer Klamm. Unpublish. report "Cyanobacteria and calcification, an introductory course for Biologists and Earth Scientists."

Our geological heritage

A new geo-journal dedicated to and about protecting geotopes - “GeoHeritage” – the first issue is free for evaluating purpose.

One of the artciles features the pale mountains :
“The Geomorphodiversity of the Dolomites (Italy): A Key of Geoheritage Assessment“

The Ehringsdorf-Formation: or travertine trouble

Even if the first descriptions of the travertine* deposits from Weimar can be traced back to J.C.W.Voigt (1781), and later Goethe draw the first stratigraphic section, only in the years after 1965 they were studied intensively and with modern methods.

STEINER (1983) described three facies in the travertine body, that in 2007 was defined as Ehringsdorf-Formation.

Spring near or marginal facies: characterized by a low topographic gradient and slow running water. In the developing shallow ponds Chara “lawn” developed and fine chalk sand or lake marls were deposited

Slope facies: strong topographic gradient with riffle-pool sequence, the water flows fast and loosing his dissolved carbonate deposits compact travertine layers, the calcification of organic material is very strong.

Valley facies: the slope changes in the broad alluvial plain of the Paleo – Ilm River, the travertine interfingers with loamy and pebbly river sediments. Then follows an alternation of lake marls, an travertine with imprints of reed.

The three-dimensional standard section of the Pleistocene travertine near Weimar is distinguished by three facies ranges following one after another in the direction of the flow of the karst spring waters which are characterized by characteristics or type rocks showing typical structural marks. From the results of the investigation the conclusion is that other occurrences of travertine probably have a similar facial, and, by this, stratigraphically complicated division. This must be taken in consideration much more than until now in all further discussions of stratigraphic questions, also in the discussion of the dating and the absolute age and coordination of paleontological finds in geological sections.

Idealized cross section trough the travertine deposits of Ehringsdorf (after STEINER 1979). White= travertine, black= "Pariser". Notable the coal bearing horizonts in the lower travertine, showing human presence.

The age of the travertine of Ehringsdorf is highly controversial. The position between sediments deposited in cold environments (the fluvial conglomerate represents a braided river system, the uppermost loess layers show ice wedges and cryoturbation) let conclude an interglacial age.

The faunal assemblage supports in part an interglacial position, with the upper part belonging to the Eemian (ca. 130.000y), and the lower part, or at least the base, dating back much further to an Intrasaalian age (OIS7 - 200.000y). The presence of Cricetus major in the soil of the Pariser seems in part to support an Eemian or older date for the upper part of the formation. The malacology on the other side seems to support older ages for both travertine bodies, typical Eemian species are lacking.
The study of human "Präneanderthalian"artefacts, with wedge like utensils and scrapers/spires showed similarities with artefacts found in Eemian to early Würmian (or in this case better Weichsel) ages sites.

The radiometric dating in 2000 using the U/Th method resulted in ages of 236+-13ka for the lower, and 198+-10ka BP for the upper travertine. Unfortunately these results are not universally accepted, the travertine is not a closed system, and water can easily enter the rock and falsifying the isotopic composition.

So still the age remains a trouble.

References:

KATZSCHMANN (2007): The Ehringsdorf Formation. In LithoLex [Online-Datenbank]. Hannover: BGR. Last updated 30.11.2007. [cited 20.06.2009]. Record No. 1000002

*Unfortunately the term “travertine” is somehow vague in different languages. Travertine limestone in English is referred to form around hot springs or by inorganic processes. Calcareous tufa forms by precipitation of calcium carbonate from “cool” springs and river waters, also improved by organic processes. To remain as near as possible to the meaning and use of the word “Travertin” in German, where the distinction is not so clear, here also travertine is used in sense of calcareous tufa.

Accretionary Warp

It´s an ice wedge... no wait - it´s an Accretionary Wedge...

Dr. Faust Fossil Collection

„When I consider the efforts I maked in this subject, no mountain was to high, no well to deep, no gallery to narrow and no cavern to puzzling.“

The german author, poet, politician and artist Johann Wolfgang Goethe (1749-1832) was also strongly interested in natural sciences, and so with geological and paleontological questions. One of his extensively studied subjects laid just for his front door, or better: under it, and also under his house and part of the city he was living since 1775, Weimar, a beautiful city located in the german Bundesland of Thuringia. Here the travertine found in the underground was used extensively as building stone and for industrial use, and was exploited since the 12th century.

Goethe was an enthusiastic collector of mineralogical, paleontological and geological, curiosities and between 1780 until 1832 he collected, exchanged and buyed at last 18.000 pieces of rocks, minerals and fossils.
Fossils comprise 718 examples, most notable are samples of the quaternary travertine of Weimar and surrounding area, with over 100 single specimens showing a large variety of plant and animal fossils. Animal fossils comprise fragments of tusks and molars of the interglacial woodland elephant Palaeloxodon antiquus, pieces of the jawbone and teeth’s of the woolly rhinoceros Dicerorhinus kirchbergensis, bones and teeth’s of the ice age bison Bison priscus mediator, also from horse (Equus taubachensis), brown bear (Ursus arctos) and antler fragments of deer (Cervus elaphus). An exceptionally fossil discovery is a petrified egg from a crane (Grus grus).

The determination and description of the fossil plants were achieved by Kaspar Graf von Sternberg (1761-1838), founder of modern paleobotany and a good friend of Goethe.

Goethe dealt with the idea to publish his observations of some of the discoveries. On 8. January 1819 he wrote to the editor and geologist Carl Caesar von Leonhard (1779-1862):
„We discovered in the vicinity of Weimar exquisite fossil bones: a half jawbone with teeth’s, similar to the Paläotherium, with remains of elephants, deer, horse and other animals that can found together.“ Unfortunately this paper never was written.

Stephanorhinus (Dicerorhinus) kirchbergensis

Equus taubachensis

Cervus elaphus

In 1821 the amateur geologist Christien Kieferstein (1784-1866) contacted him asking about in formations about the outcrops of this lithology. But at this moment Goethe was not able or willing to give further notices to him. Only two years later, after contacting the son of Goethe, August Goethe, Kieferstein received a stratigraphic description and some samples of the travertine. The young man visited during the 8. and 11. August 1823 the “tuffaceous caves out of the city limits”, collected samples and described exactly the found layers and corresponding lithology – sending the notes the very same day to Kieferstein. Goethe returned to Weimar in September, and now together with his son returned to the quarry and corrected the previously drawn stratigraphic column.
August intended to publish these observations; unfortunately his early death in 1830 prevented this intention.

"Stratigraphic column of a quarry, circa 10 min south of Weimar and just right of lake Chau after Belvedere", redrawn after Goethe 1823 (from STEINER 1996):


Symbology
1. Numbering of layers
2. plant imprints (mostly stems)
3. molluscs and mammal remains in travertine
4. compact travertine layers
5. brittle travertine layers
6. Chara and bryophyte travertines
7. mammal remains
8. molluscs
9. plant stems
10. silt
11. sand
12. solifluction horizont with pebbles
13. recent soil

The generalized stratygraphy after modern considerations:

The basis of the Succession is composed of a cemented conglomerate with crystalline and carbonatic pebbles ranging between centimetres to decimetres in diameter. This coarse river deposit is overlain by brownish to yellowish stratified silt and sand layers, interpreted as alluvial depositions. Then follows the “lower travertine“, an alternation of compact yellow with brittle travertine, also the lower part of the Eemian Ehringsdorf-Formation.
The lower travertine is separated from the upper by the so called “Pariser”, the name derives from the description by the botanist Dr. Herbst in 1860 as “Poröser Kalktuff”, meaning simply “porous calc tuff”. In the quarry it is recognizable as brown, loamy stratum that contains rare bones and teeth from small vertebrates. The “upper travertine” is similar to the lower, but differs in a gently greyish color and the presence of various pedogenetic horizons’ (“Pseudopariser”).

But still four handwritten exemplars are conserved today at the Goethe and Schiller archive in Weimar, they were used in the 20th century for the stratigraphic correlation between modern drill campaigns and old, today lost, quarry outcrops.

Bone fragment in the travertine of Ehringsdorf, a small village with the last active quarrys in the surroundings of Weimar.

Fauna of the interglacial travertine (180.000 to 200.000 years old).

References:

STEINER, W. (1996): Die Parkhöhle von Weimar. Abwasserstollen, Luftschutzkeller, Untertagemuseum. Stiftung Weimarer Klassik.

Trafoi glacier (1867)

Landscape at Trafoi in 1867, by the austrian artist Anton Schiffer (1811 - 1876).

Sometimes a tooth can come in quite handy!!!

Coming next:

(Click on the picture to enlarge)

AW: Let's Do A Time Warp!

Let's Do A Time Warp! – but what we need for it? 1,21 Gigawatts? A Warp 9 suitable space ship and a medium class star? A rift in the space-time continuum as we know it? A time machine?

Or simply an Accretionary Wedge Outside the Interzone?

Unfortunately we still not possess time travel technology, but nevertheless this doesn’t mean we are not capable to go in touch with the past. We not possess the technology to go from the present to the past, but we do possess the ability to bring the past to the present.
And considering time – and if you knew time as well as I do, you wouldn't talk about it - it's him, I’m not so fascinated by a particular point in time, but more on the passing of time.

Earth sciences deal with a fundamental problem; the study object itself is continuously destroying its own history, by rock alteration and erosion. The knowledge of rocks – and all related topics, ranging from fossil content to metamorphic events – therefore becomes more fragmented with increasing age. One might approach this historical perspective also from the opposite side: the younger the rocks, the more of them are still present. This makes the Quaternary by far the most intensively studied period – but nevertheless not necessarily the best understand – in fact, the good preservation of different facies in a restricted area or stratigraphic column, for example in the glacier forefield, is sometimes confusing simply by data excess.

So geologist and palaeontologists have to deal with rocks to reconstruct past environments and their change trough time. But not always rocks are well exposed or accessible; the bedrock is usually covered by younger soil material and/or vegetation. Even quaternary or recent sediments –often hidden only some meters under the landscape– are not always easy to reach. But like the old saying, if the mountain doesn’t came to Moses, Moses has to go to the mountain.

One possibility to recover sediments from the underground is by drilling them. If minor depths have to be reached, hand boring is a cheap and effective method. This method use is only limited by the penetration power – number of peoples pushing the borer in the underground, and by the increasing length and so weight of the rod system that can be handled and recovered. The method can largely used, for example to sample bogs, swamps and lakes in different terrain, from coastal swamps to small mountain bogs or lakes.



The recovered sediment samples can contain a lot of information’s:

-grain size distribution can give hinds for past erosion phases, large mineral grains or pebbles normally represent strong import of eroded material
- the colour of sediments give first information’s of deposition conditions, for example black sediments can show anaerobic deposition conditions
- the found minerals and chemical composition can give clues on catchment area, or chemical processes in the deposition environment
- pollen and spores can give hinds to reconstruct vegetation successions and changes trough time, and also climatic changes
- animal parts, like from arthropods, insects, microbes and even vertebrates also give precious information’s to reconstruct the past environment



So let’s see a typical sedimentation succession of some meters thickness in a former glaciated area of mid latitude, recovered by hand boring in a bog.


The basin of the former lake is commonly formed of bedrock or impermeable morain deposits of the last glacial maximum. Over them follows grey clays or silt, with no or only weak stratification, and no apparent fossil content. This sediments change gradually in white marls whit small gasteropods and bivalves, only a grey band is outstanding. Then there is a more or less distinct change in brown, plant detritus rich peaty material, with rare parts of insects.

Based on study on the fossil content, the sedimentology and deposition environment, and comparing the results with modern lakes and bogs and their fauna and flora, an attempt to imagine the story that this boring core can tell us can be undertaken.

10.000 to 18.000 years ago the great glaciers retreaded for the last time, uncovering a barren landscape, lacking vegetation cover. The basins carved by the glaciers where filled by time with water and mud, transported by rivers still feeded by small glaciers. This mud will form the grey clays. Still more time passes, the climate is warmer, the last ice melted, and the basin now is a lake surrounded by dense forests. One day of 11.000 years ago suddenly a black cloud covers the sky, and a fine, grey dust falls on the lake, where it sinks to the ground and deposits. Some hundred km distant from the lake the Laacher See Volcano erupted, covering half Europe with a small band of distinctive, grey ash.



But this event doesn’t disturb the community of animals living in the swallow, warm lake, and the carbonat rich catchment provides a high aviability for dissolved calcium in the water, an ideal habitat for a rich variety of mollusc.
More and more biogen marls deposit, filling slowly over millenia, but inexorably the basin. Plants grow in the swallow part of the lake, first mosses and aquatic plants, accumulating organic detritus and peaty material. In the middle of the forest a treeless plane extends - a bog has taken the place of the lake.


Finally, in the last centimetres’ of peaty deposits, pollen grains of cereals and other cultivated plants suggest first human settlements in the region. And only in the last millimetres’ our civilization and earth sciences develops methods to study the hidden archives of bog sediments – but also to destroy them. Lakes, swamps and bogs are one of the most threatened ecosystems in industrialized countries, threatened by urbanization and agricultural use.

All this happened in the last 10.000 years, in a single point – now consider the age and the vastity and diversity of earth itself. Realizing the age and changes in environment, flora and fauna that occurred, we obviously have to reconsider our relationship to earth and other species and also our place in earth history.

This maybe is the most important message that drilling trough time can give us.


REFERENCES:

VAN LOON, A.J. (2000): The strangest 0.05% of the geological history. Earth-Science Reviews 50: 125-133