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Material name: Banded chert from Kleinkems
Synonyms: Jaspis, weißer Jaspis (white jasper)
Material (geologic): Upper Jurassic (Malm, Oxfordian, "Rauracian") chert

Flake of material
Foto: Matthias Rummer, 2001

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General characteristics

(In part adapted from Schmid 1980 and Laternser 2001

Geographical setting: View across the Rhine towards the Isteiner Klotz
Foto: Rengert Elburg, 2001
  The Isteiner Klotz is a prominent rise on the right bank of the Rhine, ten kilometres North of Basel, 30 km south-southwest of Freiburg in southwestern Germany. When speaking of the "Isteiner Klotz", care has to be taken as the topographical and geological definitions are markedly different. In a geological sense, the area so designated stands for an about 170 square kilometres large area of Jurassic sediments that are wedged between the Rhine rift and Southern Black Forest. In a wider topographical sense it is the promontory between the villages of Istein and Kleinkems, rising about 150 metres over the Rhine floodplain as it can be seen in the picture above. On topographical maps however, the toponym is, wrongly, often restricted to the westernmost cliff near Istein, which officially should be called "Isteiner Klotz Felsen"
In the picture above you are looking from the left bank of the Rhine (France) towards the east. In the middle of the photo you can recognize the buildings of the cement factory.

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.

Material and colour: Broken nodules in quarry
Foto: Rengert Elburg, 2000
  The chert found in the Upper Oxfordian limestones occurs in four layers in the form of small to medium sized nodules, mostly not exceeding 20 centimetres in length. Most typical are a bit elongated, slightly flattened, oval nodules, like the 11 cm long specimen in the picture below, but branched and more spheric forms occur too. Measurements from a larger series gave an average length of 107 mm, with a standard deviation of 38 mm, width of 83±27 and a thickness of 55±17 mm (Engel & Siegmund 2005).
Most nodules we extracted, like the ones in the picture above, were broken, but this seems to have been caused by the blasting in the quarry, rather than by tectonic pressure. The chert is firmly embedded in the hard limestone and even though the rock was fractured, it took quite a lot of work to extract the material with a geological hammer.

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.

  Typical nodule of "Jasper"
Foto: Rengert Elburg, 2001
  The chert is very fine grained, but with a magnifying glass numerous small inclusions, the "ghosts" of small fossils are visible. These inclusions are well incorporated in the siliceous mass, and don't influence the nearly perfect conchoidal fracture, leaving an extremely smooth surface. Occasionally oolithic structures or very small quartz filled cavities (micro-vugs) can be observed.

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.

Other information: The site of Kleinkems was the first prehistoric flint mine to be discovered in Germany. During construction work near the cement factory in 1939 a human skull was discovered in a rockshelter-like structure. Subsequent excavations showed those small caves and their fill, consisting mostly of crushed limestone, where two Neolithic burials were discovered, to be human made. In combination with the large amount of flint in the fill and the occurrence of large pebbles used as hammerstones, it was rightly concluded that this was a prehistoric flint mine (Lais 1948). In 1951 the excavations were resumed, this time under participation of the German Mining Museum, and a larger part of the site was uncovered. As the four banks of chert were very firmly embedded in the hard and very dense limestone, the surrounding sterile rock had to be crushed with heavy hammers to extract the nodules. This is quite a contrast to most other Neolithic flint mines in Europe where either the (mostly Upper Cretaceous) flint is embedded in soft chalk, easily excavated with an antler pick or the weathered out silex is in a secondary position, mostly covered by loam.

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).

Knapping notes: As we have handled so many types of flint, chert, and the like, we are quite critical about the quality of any stone, but we still classify the Kleinkems/Isteiner Klotz chert as a top grade raw material. The fracture is nearly perfect conchoidal, and runs smoothly through the material. Undamaged nodules have extremely few internal flaws, and the form of the concretions, being slightly elongated and flattened makes the decortification and core preparation quite easy. Another advantage is the very hard cortex which doesn't cushion the blow when trying to split a nodule, and which can be knapped like the chert itself. Although very fine grained, it isn't too brittle. The last property makes it a bit well less suited for pressure flaking, but with a bit more force this is possible too. Apart from being very well knappable, the banding also guarantees very attractive looking artefacts.
Archaeological description: Precious little is known about the archaeology of the Kleinkems-chert and the remark of Diethelm (1997) that "..we have up to today no evident scheme as how the raw material was distributed..", still holds true, although some recent studies indicate that it is, surprisingly, more of a local raw material. The few ceramic grave goods found with the burials show strong affinities with the later phases of the Michelsberg culture, dating them towards the first half of the 4th millennium BC. The other grave-gift, a beaker made out of antler, a so called "Hirschhornbecher" is typical for the classical Cortaillod style of the alpine lake shore settlements, dendrologically dated between 3900 and 3700 BC. These dates and an association with the Michelsbergkultur is consistent with what we know about most other flint mines in Western Europe, although a date of 3000 BC is mentioned too (Diethelm 1997), but this seems very late, and is refuted by the new datings.
The five AMS-radiocarbon dates on the material from the new excavations (UtC-13237 through 13241) now give a very narrow dating range in the last quarter of the Vth millenum. All dates are of a remarkable uniformity, to the point of being statistically indistinguishable. The oldest date (UtC-13241) is 5352±31, the youngest (UtC-13240) 5306±42; all calibrated dates fall with their 1σ in the period from 4260 to 4040 BC, 2σ ranges between 4330 and 3990 BC (Engel & Siegmund 2005).

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.

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Kleinkems-Isteiner Klotz
Locality: Kleinkems-Isteiner Klotz, Lörrach district, Baden-Württemberg, Germany
Synonyms: Kleinkems-Kachelfluh. Mining-site D 1, according to the catalogue of the museum in Bochum (Weisgerber et al. (eds.) 1980); FlintSource samples 109 and 110.
Geographical description: Kleinkems is situated between the Rhine and the basis of the Isteiner Klotz, about 10 kilometres north-northwest of Basel in Southwest Germany. The prehistoric mining site lies directly to the South of the village, starting opposite the railway station. The quarry with a reasonable exposure of the limestones containing the chert is not under exploitation any more, but still not freely accessible. The whole area is going to be reorganized, along with mayor railroad-works, and it is doubtful if it will be possible to visit the site in the future.
Most of the mining site has been destroyed by quarrying and construction work, but a small part where the excavations were carried out is still intact (see below under 'sampling information').
Geographical co-ordinates: Lat. 47° 40' 53" N
Long. 007° 31' 40" E
(Mapdatum WGS 84)

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

Co-ordinate precision: As usual, the coordinates were taken with a hand held GPS receiver. They will be precise enough to get you to the quarry, which you can't miss anyway when you are near Kleinkems.
Other topographical information: The site is very conveniently situated, directly to the East of the main A5 motorway which connects Karlsruhe with Basel. Exit number 67, though named Efringen-Kirchen, lies immediately South of Kleinkems. After leaving the motorway, you turn left (North) to Kleinkems/Bad Bellingen. Take the first right, towards the railroad, and follow the tracks to the "Breisgau Portland Cementfabrik", where you can park and enter, by the way of a prehistoric looking tunnel, the head offices. Here you have to apply for permission to enter the quarry.
If you want to see the sight as shown below, just drive up to the railway station ("Bahnhof"), park your car and go to the platform where the southbound trains for Basel stop. Here you have a direct view of the site were the chert mining took place in the Neolithic.
Additional information: Platform with view of mining site
Foto: Rengert Elburg, 2000
  The photo above was taken from the platform at the station of Kleinkems. You are looking south towards the buildings of the cement factory. The excavated and preserved parts of the mining site are directly adjacent to the buildings, but the narrow terrace, now overgrown mostly with sloe, is man-made too; in this area the 2003/04 excavations were conducted.
Visitors information: As Kleinkems only lies 40 kilometres from Freiburg and is easily reached by car as well as by train, we heartily recommend staying there. Freiburg is without any doubt one of the most pleasant cities in Germany, having a very un-German atmosphere. Like most cities in the country, it was heavily damaged by bombing in the second world war, but it has been, unlike so many other German towns, rebuild on the old lay-out. There is a small but nice prehistoric/archaeological museum (open Tuesday to Sunday, 10-17h) in the Colombischlößle which is not extremely rich in flint, but still worthwhile to visit. The Münster is one of the most impressive Gothic cathedrals to be found, and around it every morning until one o' clock, apart from Sundays, there is a large market where you can buy regional products directly from the farmers. Typical specialities from the region comprise the famous "Schwarzwalder schinken" (smoked ham), "Weinhefebrant" (distilled yeast from the wine production, up to 50% by volume, so take care), "Trester" (German grappa) and honey from the pines in the Black Forest.

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.

Sampling information: If you are looking for a good sample of the material, you will have to visit the quarry of the 'Breisgauer Portland-Cementfabrik' directly South of Kleinkems. We just turned up there (spring 2000), walked with muddy feet into the offices and asked permission to get a sample. They even had a preprinted form with the usual disclaimer (if you break your neck or are crushed by tons of limestone, this is your fault entirely etc.) which we had to fill out, after which we were left to ourselves to roam the quarry. Best material is to be found at the Southern side of the quarry. Although this part is a bit overgrown, there are enough bare patches where the "Jaspis" can be taken out. According to our most recent information, the whole plant is being closed down, and there is no possibility to enter the former quarry any more.
We very strongly advise against trying to enter the area illegally, as the old faces of the quarry are high, steep and not very stable. We will try in the future to locate another accessible source of the same chert in the region, although this proves to be quite difficult.

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.

  Flake of typical chert
Foto: Matthias Rummer, 2001
Flake of typical chert
length: 45 mm
Cross section of typical banded nodule
Foto: Matthias Rummer, 2001
Cross section of typical banded nodule
breadth: 94 mm
  Slightly patinated flake
Foto: Matthias Rummer, 2001
Slightly patinated flake
length: 22 mm
Split grey nodule
Foto: Matthias Rummer, 2001
Split grey nodule
width: 50 mm
Sample description: The flake left in the top row is a very typical specimen of the chert to be found at Kleinkems. It was struck of a nodule broken out freshly from the limestones in the quarry. The split nodule next to it gives a good idea what the material looks like on a larger scale with the typical, slightly brownish banding.
In the bottom row there are a slightly patinated flake which we picked up from the surface near the railway station and next to it is a small greyish nodule with only very slight zoning. Fur further description of the material, see the general section above.


Last modified on:
February 28, 2006
Contents primarily by:
Rengert Elburg
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