Classic Trochactaeon and rudist sites at Waaggraben, Hieflau, Styria, Austria (Gosau-Group, Upper Cretaceous)

[FranzBernhard]

Hello,

last Saturday (10/09/2021), I visited again some classic fossil sites at Waagraben, Hieflau, northern Styria, Austria with a friend. These sites are known since around 1850, are probably of Coniacian age and belong to the Gosau-group. First, some maps: Overview with location of Waaggraben in Styria, a geological map from Ampferer, 1935 (1 = rudists; 2 = Trochactaeon; 3 = Conglomerate quarry), topo-map, and DEM. These sites are very well known, so no problem to pinpoint them exactly on maps:

 

 

On the way. We will meet this guy in the background near the car again:

 

Conglomerate quarry:

First, we visited the surroundings of a historic conglomerate quarry, first mentioned in 1509 and intermittently worked until 1974. It worked an interglazial, well cemented, mostly white conglomerate, used as high-quality building stone or mill stone, but sometimes also as decorative stone. This are the remnants of the old smithy, the quarry itself is heavily overgrown:

 

View back with some houses of Hieflau, to the left some remnants of the smithy:

 

Rudist site:

Lots of rudists (mostly hippuritids, some radiolitids, few plagioptychides), mostly found at both sides (shoulders/berms) of the forest road. This time I focused also on specimens with large diameter (Vaccinites) and we found a few. (I have seen one from this site in a collection, but have not stumbled upon one during my last visits from 2014 to 2015. But when you know...). The rudist outcrop near the road is also still there and untouched. Found also a few Plagioptychus, but they were not my goal. Lots of rudists also in the steep forest below the road, coming all from periodical road cleaning/grading. Funnily, the furious forest ranger showed up (we knew already that such a crazy guy is around in that area). He shouted: "No digging, no digging!! I have your car number." "We are only looking at the road." "A fat lot I care about that (Nice translation of Styrian "Das ist mir wurscht!"), but no digging, no digging, I have your number." Turning around and escaping with high speed. Such a crazy guy .

 

Overall view from southeast and northwest, respectively. A little bit to the upper right from the center of the second pic, you can see some old diggings. This is what the guy was crazy about: "No digging!!". But I can understand, look at the tall outcrop of rudist limestone above the road. Severe undercutting not recommended! At the red X is the "permanent" rudist outcrop at the forest road:

 

Rudist outcrop at forest road, its composed of Hippurites species. There exits a master thesis from 2015 about this site and the surrounding, if anybody is interested:

Waaggraben Rudist Limestone (in English, ca. 6 MB, pdf, hosted at Uni Graz):

 

Rudist fragments (mostly Hippurites) below this outcrop, as found:

 

Some crushed pseudocolonies of Hippurites, as found, pseudocolony in second pic is 16 cm high:

 

Trochactaeon site 1:

In the year 2014, I found several Trochactaeon in the shoulder/berm of the forest a little bit downhill of the rudist site. Yesterday, dozens of snails showed up, all at the surface of the shoulder. (The driveway itself has foreign gravel spread over it). At one spot, they seem to crop out in the shoulder (red x). I took a total of 6 specimens, how many snails can you spot in the second pic? The host rock of the snails is a sandy marl with lots of white spots, made of an unknown fossil (at least unknown to me). You can see some to the left of the red object in the second pic:

 

Trochactaeon site 2:

This is the classic (known since about 1850) Trochactaeon site at Waaggraben. Its situated near the creek and it has changed considerably since my last visit in 2016, because the area above the digs was clearcut some years ago. Due to better lighting, the steep hillslope is now quite heavily overgrown with grass and such things, you have to know where the digs have been located. Anyways, just a few meters downstream, a new dig hole has been opened up by someone, and was last visited only a few weeks ago. Lots of Trochactaeon left behind (everything is veeery muddy, not easy to spot), but we took nothing, we had enough.

New dig hole (red x) and debris below, veeery dirty, very dangerous (overhang!), no fun to work in that hole:

Old dig holes, barely visible:

 

Pic from 2014 showing about the same area with well visible dig holes:

 

View from above with one quite recently activated old dig hole (red x):

 

Here are some polished specimens of Trochactaeon from Waaggraben of my finds from 2014, box is 40x30 cm:

 

Polished specimen with typical "spotted" host rock (sandy marl)

 

Hope, you enjoyed a little bit . Thanks for looking!

Franz Bernhard

Edited October 10, 2021 by FranzBernhard

[Tidgy's Dad]

Splendid! 

Lovely photos, very informative and super fossils. 

Love the polished snail sections too. 

[Jared C]

What fantastic scenery to be hunting in, and I love those great polished specimens 

[FranzBernhard]

On 10/10/2021 at 2:20 PM, Tidgy's Dad said:

Lovely photos, very informative and super fossils. 

Love the polished snail sections too.

 

13 minutes ago, Jared C said:

What fantastic scenery to be hunting in, and I love those great polished specimens

Thanks to both of you!

 

These Trochactaeon snails are the classic Austrian fossil in terms of commonness and distribution. There are several still productive occurrences across Austria, known since at least around 1850. You can find a polished cross section of these snails in many households, not only in collector´s caves . You may find quite a lot googling for Actaeonella (the old name) or Trochactaeon.

Most of the specimens shown above I have already given away. Unfortunately, I can no longer cut large specimens (only with diameter < 6.5 cm), so I am mostly unable to replace my stock at the moment. But seeing so many in the field just to be picked up, I may think about a solution....

Franz Bernhard

[RuMert]

Fantastic report, very informative

[Paleorunner]

Well, and nice report.
Nice and curious polished pieces.