Regmaglyptic cobbles from Lake Chiemsee: Evidence of meteorite impact-induced ablation features

Well known among people around Lake Chiemsee, peculiarly sculptured limestone cobbles (Figs. 1 – 4) found at the shore and offshore at the lake bottom attracted special attention when Lake Chiemsee got into the focus of the meteorite strewn field impact research. Although most people are considering the groove cobbles no more than a freak of nature, the work of organisms, especially of mussels has always been suggested.

Fig. 1. Typical conically shaped groove stone from the Lake Chiemsee shore – originally a Quaternary fluvio-glacial limestone cobble. Photo courtesy of H. Eberle.

Fig. 2. Various aspects of groove cobbles from Lake Chiemsee. Photos courtesy of H. Eberle and T. Schwaier.

Fig. 3. Big grooved limestone block from the Lake Chiemsee shore. Note the distinctly parallel, knife-edge ridges between the grooves (in the same orientation found all around the block) hardly compatible with the work of organisms.

Fig. 4. Pyramidally shaped groove stone. Note the geometrically orientated groves. Photo courtesy of H. Eberle.An impact-related formation came to the fore comparing the typical groove features with ablation features (regmaglypts) that meteorites may acquire when exposed to frictional heat on their passage through the Earth’s atmosphere. Moreover, an amazing similarity between the groove cobbles and regmaglyptic boulders from the Puerto Mínguez impact ejecta of the Spanish large Rubielos de la Cérida impact structure (Figs. 5, 6; also see the respective article: exists. When we suggested that the cobble grooves were formed in the Chiemgau impact event as ablation features having developed by decarbonization and carbonate melting upon ejection and heating in a jet of super-heated volatiles, immediate reactions of local geologists ensued.

As later adopted by the local geologist Dr. Robert Darga, Dr. Robert Huber from the university of Bremen rejected the impact model of groove formation and instead seized again on the old explanation of the work of organisms, especially of bacteria and algae. He underlined his belief claiming that the same groove cobbles are a common feature in many lakes in the Alpine Forelands, Lake Constance included – see his blog contribution We encourage you to read his remarks and to especially enlarge the photos in Dr. Huber’s blog comparing them with our photos from Figs. 1-4. It’s like comparing apples to oranges. And until today, Dr. Robert Huber fails to present groove cobbles like those shown in our figures from lakes other than Lake Chiemsee.

Of course, biogenic rock sculpture produced by organisms like, e.g., endolithic bacteria or piddocks is a well-known process, but once more, we must not compare apples to oranges, and obviously Dr. Huber has come to a deadlock.

There are very simple macroscopic observations proving the inorganic formation of the grooves. As shown in many of our photos, the grooved cobbles frequently exhibit distinct conical and pyramidal shape while the grooves, in most cases showing extremely sharp, knife-like edges, are geometrically related with the cones and pyramids. It’s exactly the same observation we are making with the regmaglyptic stones from the Rubielos de la Cérida impact ejecta (Figs. 5, 6). If the grooves were produced by organisms, these bacteria, algae and mussels must have had extraordinary intelligence, organization and communication capabilities to geometrically sculpture a large block as seen, e.g., in Fig. 3. Moreover, the identically grooved stones from the Spanish impact ejecta have never seen a lake, as can be read in more detail in the article referred to above.

In summary, a biogenic origin of the unmistakable, distinctly grooved cobbles from Lake Chiemsee has not any reasonable base. Instead, all features, the frequently conical and pyramidal orientations included, point to an erosion process initiating ablation due to decarbonization and melting.

Meanwhile, new finds of quite a few grooved cobbles (among them also grooved sandstones) substantiate the impact-related formation and, moreover, give highlighting insight into the unique process of deposition of the cobbles after having acquired their sculpture. We will report soon.

Fig. 5. Big grooved limestone clast embedded in the diamictic impact ejecta of the Rubielos de la Cérida impact structure in Spain. Note the pyramidal shape and the grooves diverging from the top of the pyramid.

Fig. 6. Regmaglyptic conically shaped limestone clast from the Puerto Mínguez ejecta of the Spanish large Rubielos de la Cérida impact structure. The clast that never saw any biogenic activities in a lake has remarkable similarity with the Lake Chiemsee groove stones.

An impact layer at Chieming-Stöttham

More than 30 excavation pits in the environs of Lake Tüttensee have encountered an impact layer that is suggested to be ejecta from the formation of Lake Tüttensee as a meteorite crater in the Chiemgau impact event [http://www.chiemgauimpact. com/artikel2.pdf]. Now, a very similar situation has been found with archeological excavations in the border area of Lake Chiemsee near Chieming-Stöttham. Undisturbed glacial drift with a fossil soil is overlain by a layer that must be interpreted as the result of a catastrophic event in the recent geological time. Like at Lake Tüttensee, the layer is composed of a multicolored mixture of deeply corroded rock fragments in a clayey matrix. Organic material like charcoal, teeth and bones as well as archeological objects are intermixed. This “catastrophe” horizon is overlain by a younger undisturbed occupation layer (Roman) and recent soil formation. Similar to Lake Tüttensee, the archeological finds and the geologic-archeological stratigraphy date the catastrophic event to have happened many thousand years after the end of the glacial period.

Fig. 1. The excavation pit and layering at Chieming-Stöttham exposing the “catastrophe”horizon (light, roughly in the middle of the image)

Fig. 2. Close-up of the impact catastrophe layer.

Because of the great distance to Lake Tüttensee, a formation of the Stöttham “catastrophe” horizon as ejecta from that crater can be excluded. Instead we propose another nearby impact, and there is some evidence that an impact into Lake Chiemsee was involved at least

Fig. 3. Another exposure in the area of the archeological excavation. Here, the roughly 2 m deep pit cutting through the “catastrophe” layer has not encountered the autochthonous ground moraine. In comparison with Fig. 1 the exposure shows the fluctuation of thickness and composition of the layer. Many of the dark components are intermixed charcoal.

A new geophysical campaign at Lake Tüttensee crater

Geophysical measurements play an important role in the research on meteorite craters (impact structures). The unusual pressures, temperatures and mass movements closely related to meteorite impact result in partly drastic changes of the physical properties of the target rocks. These changes correspond to characteristic geophysical anomalies, and many a crater buried deeply in the Earth’s crust have first been discovered by geophysical soundings.

In an earlier geophysical gravity survey at Lake Tüttensee, a peculiar ring of positive gravity anomalies was measured to have possibly resulted from a shock densification [article]. Now, we conducted a new campaign of geophysical measurements in the zone of impact ejecta that have been encountered in more than 30 excavation pits around Lake Tüttensee.

Fig. 1. Klaus Ebinger (to the left), owner of the EBINGER company, during the Tüttensee crater geophysical campaign.


 Fig. 2. Pulse electromagnetic (TEM) survey at Lake Tüttensee using the EBINGER UPEX 740 M Large Twin Loop equipment.


The geophysical survey comprised pulse (TEM) and frequency (FEM) electromagnetic soundings, and the primary objective was an area-wide investigation of the impact-related geological underground und its peculiarities so far only known from selective excavations around Lake Tüttensee.

The campaign was generously supported by the EBINGER company (Cologne) [Ebinger Prüf- und Ortungstechnik GmbH], a worldwide operating producer of high-tech search and detection equipment (Fig. 1). The EBINGER products are applied to various fields like unexploded ordnance (UXO) disposal both by sea and by land, safety engineering, environmental geophysics, industry and research, and in this particular case the EBINGER company in a three-day campaign (Fig. 2) supported at no charge the research of the Chiemgau Impact Research Team (CIRT).

From that campaign, Fig. 3 shows an example of processed pulse-electromagnetic (TEM) data sampled on an area of 150 x 100 m². The map exhibits conspicuous resistivity contours that, however, need further interpretation.

Fig. 3. Pulse-electromagnetic (TEM) resistivity mapping at Lake Tüttensee crater using EBINGER Large Loop equipment.

A peculiar prehistoric artifact in the Tüttensee impact ejecta (“Bunte Breccia”; Chiemgau Holocene impact event)

In the environs of the Tüttensee crater (Chiemgau Holocene impact event), a new campaign of geological and geophysical investigations has been performed also including new excavation pits (now totaling 37).

In the excavation pits, the stratigraphy well known from earlier excavations [] has again been encountered (top down):

recent soil

layer of Tüttensee impact ejecta (“Bunte Breccia”)

fossil soil horizon

autochthonous ground (lacustrine clay)

The ejecta layer exhibits the well-known composition of crushed, yet abundantly coherent clasts and the frequently strongly corroded skeletal carbonate and silicate cobbles and boulders in a clayey matrix (Fig. 1).

Fig. 1. Typical, strongly wrecked cobbles from the Tüttensee impact layer in excavation pit No. 35. Together with these cobbles the quartzite artifact (Fig. 2) was recovered. As noted in previous articles, the sharp-edged fracturing can only have originated from impact deformation, and the extreme corrosion of the clasts can be explained by impact nitric-acid dissolution and/or carbonate decarbonization/melting.


As a peculiarity in the Bunte breccia ejecta layer of excavation pit No. 35, about 900 m east of Lake Tüttensee, a broken white quartzite boulder was recovered that

has clearly been elaborated by man (Figs. 2, 3). A funnel-shaped “picked” dent passes over into a drilled hole that breaks off midway through the boulder. A central rise at the base of the hole (Fig. 3) proves it was drilled with a hollow rod, possibly a hollow bone.

Fig. 2. The drilled quartzite boulder recovered from the Tüttensee impact ejecta layer.


Fig. 3. Close-up of the bore. The central rise at the base proves the use of a hollow rod, possibly a hollow bone.


It is well known that artifacts were produced from impactites and impact glasses, resp., (e.g., Elgygytgin impact structure [Gurov & Gozhic, 2006, Impact Cratering in the Earth’s History, in Russian], Libyan Desert glass, tektites). Here, in the Tüttensee case, obviously the first find of an artifact in an impact rock is documented.

The full article on this find can be clicked here.

A leveled crater near Perach in the Chiemgau impact strewn field

The air photo (1)* originates from the northern part of the impact strewn field near Perach and shows (arrow) a crater leveled on an acre.

  Image 1: Chiemgau impact; leveled crater near Perach
Source BLfD

  Image 2

By image processing, the in the original photo only adumbrated structure gains amazingly sharp contours (2) clearly exhibiting four different concentric zones (3):

  • a 5 m-diameter central area (black)
  • a 12 m-diameter adjoining zone (red)
  • an annular Zone not quite 10 m wide and with an outer diameter of c. 30 m (yellow)
  • an exterior zone (60 – 70 m diameter) displaying extensions radiating up to 50 m from the center.

  Image 3

The following attribution of the individual zones is suggested:

The interpretation of the central spot orients by the GPR (ground penetrating radar) measurements (Dr. Patzelt, Terrana Geophysik; in  and that have been conducted over another crater (our crater no. 004 – also see located in the northern part of the strewn field. The GPR soundings show prominent reflections from the crater floor possibly related with strong compaction of the underground material. Assumed this compaction also exists within the Perach crater serving as impermeable rock, a corresponding moisture penetration could optically be traceable to the surface.

The adjoining 12 m-diameter zone could represent the material from the leveling of the crater. The annular zone is suggested to reflect remnants of the original rim wall. Taken the middle of this zone to have been the location of the rim crest, a 20 m diameter of the original crater results.

Finally, the exterior zone is suggested to reflect the zone of the crater ejecta radiating up to 50 m from the crater center.

This documentation of a ring structure illustrates that alternate explanations (geologic glacial formations, anthropogenic (archeological) structures, primitive industrial sites) readily and frequently given by opponents of the Chiemgau impact and skeptics of the meteorite origin for the innumerable craters, continue to have a hard time.

In any case, it is planned to investigate the Perach leveled crater by various geophysical measuring systems trying to characterize the optical zoning in more detail physically.


* In earlier texts, the air photo was erroneously labeled an infrared image.

From the Tüttensee Bunte breccia

Repeatedly, the Tüttensee ejecta layer has served for the Weekly Images, which can be tracked in the Archives of this website. Now, we present several especially beautiful individual components after having released them from the clayey matrix of this polymictic breccia. As for the term “breccia”, we note that according to current

classification a breccia is a clastic sedimentary rock composed of angular clasts in a cementing matrix. The rounded clasts encountered in the Bunte breccia seem to contradict this definition, the case, however, is to be comprehended as follows: Upon impact in the area of the today’s Tüttensee, a conglomeratic rock composed of Alpine lithologies was shattered whereby components of the fragmentation could survive as rounded cobbles to become incorporated in the breccia. Correspondingly, well-rounded clasts can be found within the Bunte breccia ejecta of the Nördlinger Ries impact structure (e.g., the so-called Buchberg cobbles).

Image 1. Chiemgau impact ejecta: Strong corrosion of a limestone boulder.

The here presented cobbles and boulders from the Tüttensee Bunte breccia stand out to have still more experienced. We explain the deep-reaching corrosion and rock dissolution right up to skeletal formation by the action of high temperatures or/and the action of strong acid dissolution.

The voluminous boulder in Image 1 is a limestone that because of its peculiar sculpture can impossibly have come from the Alps as is (note, e.g., the roughly central fine pin). Obviously, a noticeable part of the rock has been removed, and that did not happen by fracture. Instead, we suggest high temperatures in the impact process being able to melt a limestone or, like in lime works, to decarbonize it. We also consider a dissolution by nitric acid that may be produced in the impact explosion cloud, as previously discussed here on our website. Both processes heat and acid need not be mutually exclusive.

Image 2. Chiemgau-impact ejecta: strong corrosion of a sandstone cobble.

Image 2 shows a sandstone component from the Bunte breccia already, joking,  called a saurian embryo. For the formation of this “sculpture” we can refer to the same processes of destruction. If the quartz grains of the sandstone are carbonate-cemented then on action of temperature and/or acid a deep-reaching corrosion starts. On decreasing temperature and acidity rock skeletons as shown may remain.

The same carbonate disintegration applies to the boulders shown in Images 3 and 4. The pervasively corroded limestone and dolostone, resp., exhibit sharp-edged sculptured ridges representing quartz dikelets that need significantly higher melting temperatures and are by far more acid resistant

Image 3. Chiemgau impact ejecta – strongly corroded limestone/dolostone from the Tüttensee excavation.

Image 4. Corroded limestone boulder from the Tüttensee ejecta.

We would like to once more point out that the drastic rock modifications shown here are observed with clasts that are constituent part of a rock, namely the Bunte breccia. Recently, geologists of the Bavarian Geological Survey (now Landesamt für Umwelt) have explained the deep-reaching skeletal corrosion of clasts from the impact layer by sour soils, which we don’t want to comment any further.

Image 5

The clast shown in Image 5 also originates from the Tüttensee impact layer. It was encountered at some 1.5 m depth at the base of the Bunte breccia pushed-in in the fossil soil horizon underneath. The boulder is a hard, dense quartzite and exhibits distinct abrasions all around. Not any striations can be observed on the surface of the rock, and the imprints cannot possibly have originated from glacial abrasion – in order to preclude respective objections by deniers of the Chiemgau impact. The directional imprints are smooth suggesting a plastic, if only short, behavior (like a pulp) of the quartzite material. Within the frame of our model that defines the Bunte breccia to be ejecta from the Tüttensee crater, the boulder underwent the excavation of the growing crater initiated by extreme shock pressures following the impact into the target of Alpine material. During this high-pressure phase, the boulder became plastically deformed by neighboring clasts was ejected and landed on the (at present fossil) soil at the base of the developing Bunte breccia ejecta horizon.

Bones and teeth from the impact layer (ejecta, Bunte breccia) at Lake Tüttensee (Chiemgau impact event).

In numerous excavation pits around Lake Tüttensee, a polymictic breccia layer has been encountered to be probably impact ejecta from the Tüttensee crater  ( ). In a clayey matrix, the breccia contains multicolored rock fragments exhibiting shock-metamorphic effects ( ), and is rich in organic material like wood and charcoal. Moreover, bones, bone fragments and teeth were found in the breccia from four excavation pits. Meantime, for two bones and two teeth a more accurate determination has been performed by Dr. M. Mäuser, director of the Naturkundemuseum (Museum of Natural History) in Bamberg.

Bone 1 (excavation 11; image 1) is a cattle’s second phalange (toe bone). Bone 2 (excavation pit 11, image 2) belongs to the left astragalus (talus bone of the ankle) of a deer, probably a red deer (possibly a fallow deer). Tooth 1 (excavation 25, image 3) is an upper-jaw molar of a goatish (Caprinae). Caprinae include sheep and chamois but also goats and the ibex (capricorn). The size of the molar speaks in favor of a sheep or an ibex. Tooth 2 (excavation 25, image 4) probably is a Caprinae milk premolar.

It is left to assumptions whether the animals perished on impact or whether the skeletons existed already and were smashed and intermixed in the impact breccia. Sheep and cattle may have been domestic animals

Shock effects (shock metamorphism) in rocks from the impact layer (ejecta, Bunte Breccia) at Lake Tüttensee

Quartz grains in mica gneiss from the Chiemgau impact Tüttensee ejecta layer – full of planar deformation features (PDFs).

Two sets of crossing kink bands in mica. Shock effect from the Chiemgau impact Tüttensee ejecta layer.

Numerous excavation pits have been performed in the surroundings of Lake Tüttensee that is proposed to have formed as a meteorite crater in the Chiemgau impact event. The excavation pits have revealed the existence of a more or less continuous ejecta blanket around the lake, and the peculiarities of the layer have already been described: (part 1) and (part 2). Now, samples (from crystalline and sedimentary Alpine cobbles) were selectively taken from this ejecta layer in order to systematically analyze them for shock effects, for the time being under the optical microscope only. The study of thin sections from 31 rock samples taken from 7 different excavations establishes a rich inventory of mineral deformations that with reasonable certainty or with great likeliness have originated from shock load. The photomicrographs (crossed polarizers) show planar deformation features (PDFs) in quartz from a mica quartzite (upper) and two sets of extremely closely spaced kink bands in biotite from a gneiss (lower). A more comprehensive report including 17 photomicrographs (in German with English abstract and figure captions) may be clicked HERE.