Kleinkems-chert

Sampled sites:
• Kleinkems-Isteiner Klotz

The geology of the area is quite straightforward, although the still continuing use of geological pseudo-stages like "Rauracian" and "Sequanian" causes unnecessary confusion. The base of the stratigraphy is formed by Lower Oxfordian marls with concretions of the Kandern-Formation (unit oxKA on the local geological map number 8311 "Lörrach") that can be linked to the french "Argilles à Chailles". Above these we find up to nearly 70 metres of limestones of the so called "Korallenkalk-Formation", of Middle Oxfordian age (unit oxK).
This formation consists of three subunits, from below the "Thamnastreenmergel", a layer of marl with a thickness of 5 meters, 40 meters of reef-built Korallenkalke proper, and topped by the Splitterkalken, so called after their sharp and angular fracture, with a thickness of 23-25 meters. This last unit, very hard micritic to oncolitic/oolithic limestones, contains in its lower part four banks of chert nodules, that were mined during the Neolithic. On top of this stratum there lie the "sequanian" limestones of the "Nerineenkalk-Formation" (unit oxN) which are covered, after a large hiatus, by mostly tertiary sediments and quaternary loess.

In most of the German literature the material is wrongly called Jaspis (jasper). Independent of which definition of jasper you use: a cryptocrystalline siliceous volcanic rock associated with melaphyr (as we do), any reddish chert or radiolarite (most American archaeologists) or secondary coloured chert (quite a lot of German and French archaeologists), this material is definitely not jasper. For international use it should be called "chert", according to the local, German, conventions it should be classified as a "Hornstein" (hornstone). How this stuff came to be called jasper is a complete mystery to us.

One of the main characteristics of the material is its very smooth and hard cortex, which reminds of porcelain, and causes the nodule, once taken out, to leave a perfect imprint in the surrounding rock. The transition between the siliceous core and the cortex is very sharp, mostly accentuated by a band of darker and glassier chert directly under the cortex.

Nearly all nodules are banded, but the degree of zoning is highly variable, with some pieces, like the grey nodule below, being nearly homogenous. The banding is always more pronounced in the outer part of the nodule, the core being more even and lighter coloured. The colour of the core and the light bands varies between white (N8, 5YR to 5Y 8/1), pinkish white (5 to 7.5YR 8/2) and very pale brown (10YR 8/2) to light gray (10YR to 2.5Y 7/1-2) and gray (10YR to 2.5Y 5-6/1). The darker bands can have several shades of brown and gray/brown like 10YR to 2.5Y 5/2 (grayish brown) and 4/2 (dark grayish brown) to plain brown (7.5YR to 2.5Y 5/3), with nearer the core light brownish gray (2.5Y-10YR 6/2) to pale brown (10YR 6/3) and light yellowish brown. Translucency varies strongly and correlates with colour: the lighter parts are only slightly translucent, the core sometimes nearly opaque, the darker bands transmit light over considerable thickness.
Although being very fine grained, the silex has hardly any gloss. If present, it is mostly slightly silky and confined to the darker parts, the lighter coloured material in a fresh, untreated state, is matte. Patination, as far as we have seen it, lessens the difference in colour between the bands without obliterating them and gives the material a bit more glossy surface, as can be seen in the photo of the lightly patinated flake below.

Careful excavation showed traces of fire on the flint-free limestone, always stopping well short of the chert bearing levels, and layers of backfill with a high charcoal content, which led the excavator to believe prehistoric miners used fire to soften up the bedrock. After firing, possible combined with forced cooling by water, the limestone came away in large chunks, whereafter the chert nodules were picked free with hammerstones. Experimental firing showed this method to be very effective indeed, more than ten times the amount of rock could be excavated, with less effort, compared with the untreated limestone. Quenching with water again doubled the amount of material that could be cleared.

Unfortunately, most of the mining area has been destroyed by the construction of the railroad that runs immediately next to the cliff, combined with the large cement quarry just south of Kleinkems. On the basis of the discovery of hammerstones, worked flint and crushed limestone at several spots along the cliff, the length of the workings are estimated at 1200 metres. No estimates of how much chert has been extracted are available.

Recently new excavations have been carried out by the University of Basel under the direction of Prof. Siegmund to clarify the exact stratigraphy as the original documentation from the excavations in the 1950ies has been lost, and to collect samples for the long-overdue radiocarbon dating of the mining site. In 2003 and 2004 several trenches have been cut through the mining debris between 25 and 60 metres north of the location of the burial-site, from which a large amount of charcoal samples could be collected (Engel & Siegmund 2005, see online resources).

About the distribution of the chert much less is known. A few finds are reported from Middle Neolithic from Überau near Frankfurt/Main (270 kilometres to the north-northwest), as well as from the area around Freiburg (Zimmermann 1995). To the East, the distribution reaches at least the Western end of the Bodensee (Lake Constance), a distance of about 100 kilometres (Schlichtherle 1994). In northern Switzerland only occasional pieces have been found (Affolter 2002).
We haven't got any positive data about the material occurring on the other side of the Rhine in Eastern France, but here at least its use on a somewhat larger scale is very probable as the area is very poor in high-quality raw materials.

The Coordinates given are those of the quarry where most material was collected. The mining site lies approx. 300 metres to the North.

Infrastructure is very good, with a lot of (mostly quite costly) hotels and a nice camping ground at Hirzberg at the Eastern side of town. We can't recommend any of the hotels as we stayed mostly with friends and colleagues or camped at the above mentioned site. Among the pubs there is "Gasthaus zum Bären", the oldest guesthouse in Germany, but our favourite is "Schlappen", a mostly student filled place which serves decent food too, and has the most curious toilet facilities in the gent's room we set eyes on. Also very recommendable are several places like the Hausbrauerei Feierling that brew their own beer.
The best beers in the region are "Rothausbräu" and "Fürstenberg", both a bit lager-like but fuller. Of the many wines of the region, we mention only our favourites like Weiß- Grau- and Rotburgunder (Made of white, gray, and black Pinot grapes respectively), Gutedel and of course Riesling and Gewürztraminer. Very nice are the Weißherbst wines, a kind of light rosé, especially when made of the "Spätburgunder" grape. Do not drink Müller-Thürgau.
Local food is certainly not (only) the "Bratwurst mit Sauerkraut"-type, mostly associated with Germany: the vicinity to the French border makes itself clear. Like in all of Southwestern Germany, "Spätzles" (short irregular egg-noodles), is a favourite. Served au gratin with cheese (Käsespätzles) or a cream sauce and veal (Sahnegeschnetzeltes) they are exactly what you need after a day hunting flints and as a basis to do some serious sampling of the local drinks.

One of the main attractions outside the city are the so called "Straußenwirtschaften". Most of these places are old farmhouses or wineries that serve their own or local wines and home-made food. They are to be recognized by a old-fashioned broom hanging at the roadside. But also quite a lot of more regular pubs and restaurants in the region serve very good food, but prices are often accordingly high, although good value for money is the rule.

If you want to visit the excavated mine, which we didn't do on a regular base as we only were there during the newest excavations, you will have to contact the museum in Efringen-Kirchen. This local museum has a small exhibition which also covers the chert mining in Kleinkems with some blocks of the limestone with chert embedded, as well as a well-made model of the prehistoric mining site. The museum is open on wednesday and sunday afternoons only, but it can be reached by phone under +49-(0)7628-8205. The site is locked, and they don't have the key at the cement works, so you will have to join a visit organized by the museum.

If you want to pick up some pieces of chert at the foot of the cliff, you will have to cross the tracks at the railway station in Kleinkems, something which is, naturally, strictly forbidden. If you decide to trespass anyway, which we again strongly advise against, be extremely careful as this is a major line, connecting most of Switzerland with Western Germany. There are quite a lot of High Speed trains that hardly brake at the station, as only local trains stop at Kleinkems, so don't blame us if you got run over.