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Rudist collecting at Roemaskogel hill, Kainach, Styria, Austria (Afling-formation, Gosau-group of Kainach, upper Santonian - lower Campanian) - 05/15/2021


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FranzBernhard
Posted (edited)

Hello!

Having discovered some new rudist occurrences in the lower part of the upper Santonian - lower Campanian clastic-marine Afling-formation at Römaskogel hill near Kainach, western Styria, Austria, about 6 weeks ago. Here I would like to present a very specific visit to one of these sites at 05/15/2021. It was aimed to recover some more parts of already known rudists from the outcrop at site #30.

 

Here we go!

Approaching Römaskogel, the hill in the middle. Its 1006 m high, the snowy mountain in the background is the Gleinalpe mountain, nearly 2000 m high:

Roemas_Fern_08052021_klein.jpg.b8b9b94e998951194815861d3c6501fe.jpg

 

Already near Römaskogel hill, again the hill in the middle. These meadows are much steeper than they appear in the pic:

Roemas_Nahe_08052021_klein_kompr.thumb.jpg.a8e9010c3c22626a3f537ccd6fe43914.jpg

 

Location of the rudist outcrop along a forest road:

Punkt30_15052021_Annaeherung_klein_kompr.thumb.jpg.5e364d291f33a14ab730ec047289f225.jpg

 

 

Rudist outcrop, scale is 1x1 m. The rudist-bearing zone is about 80 cm thick and tips gently towards south to southeast. Individual conglomeratic rudist-bearing beds are separated by layers of siltstone. The whole extensions of the rudist-bearing zone seems to be at least about 300 m, with about 5 outcrops and indications known until now. This is the best outcrop discovered so far.

Punkt30_15052021_Uebersicht_mitBeschriftung_klein_kompr.thumb.jpg.9df9ed23456f647a70e1329e3f30a30c.jpg

 

Right part of the rudist outcrop. At the lower end of the scale, the next pic. The digging spot of this day is to the left of the pen:

Punkt30_15052021_Rechts_vorher_klein_kompr.thumb.jpg.6f64c4cd40b3ce435147bf89833891e7.jpg

 

Rudists ("Vaccinites Rö1") in conglomerate in the outcrop, diameter is about 5 cm:

Punkt30_15052021_Rudisten_klein_kompr.thumb.jpg.32e0e0b0d06b2e226622f907014245f2.jpg

 

The digging site as left at 05/06/2021 and found again a week later at 05/15/2021. I had already recovered two parts of #4901 and one part of #4910. The soft siltstone in the footwall of the rudist bed clearly facilitated the recovery of the remaining parts from the relatively hard conglomerate. The pen is 13.7 cm long:

Punkt30_15052021_Detail_vorher_klein_kompr.thumb.jpg.41a9645b3cad0560121b473e993968ab.jpg

 

Intermediate stage of recovery. The rudists are orientated parallel to the bedding plane. They are flattened, the two big ones lying with the flat side on the bedding plane. The smaller one is orientated "on edge" to the bedding plane:

Punkt30_15052021_Detail_dazwischen_klein_kompr.thumb.jpg.203aa3a45957c44b921284a13a52ce25.jpg

 

Here is a primitive, highly schematic and out-of-scale sketch of the situation. #4901 and #4910 are also oriented antiparallel:

Skizze_Punkt30_15052021.jpg.fcfcad8fc91312a0c55bca56e4ea4afc.jpg

 

Dig site after removing all the rudists. #4901 yielded two more fragment (total of 4), with the very last tip still remaining in the outcrop. #4910 yielded also two more fragments (total of 3, completely recovered). #4914 recovered in two fragments:

Punkt30_15052021_Detail_nacher_klein_kompr.thumb.jpg.b826e924f5368498462f723597f4a56b.jpg

 

Right part of the rudist outcrop after recovery of these three rudists. Notice the difference to the start of the recovery ;):

Punkt30_15052021_Rechts_nacher_klein_kompr.thumb.jpg.8160cf69715380f0ecf11dcd25e0869f.jpg

 

Here is the complete specimen #4910. It consists of 4 fragments, that were already naturally broken. Uppermost part was found 05/01/2021, next part was found 05/08/2021, lower most parts are from 05/15/2021. The rudist is strongly flattened (about 1:2), as most of the specimens from this bed, and about 21 cm long. I don´t know the species yet, working name is "Vaccinites Rö2". (Remember, nothing was known in that area until about 6 weeks ago.) The shell has a flame-like structure, which can be nicely seen in the naturally weathered transverse section. These structure corresponds to the fine longitudinal striation of the shell. Otherwise, the rudist is smooth without any ribs. In the cross section, the P-pillars are barely visible to the right, the L-pillar is not visible:

HS_4901_Roemas_30_klein_kompr.thumb.jpg.b240df22d4bbff08e07098e523d296e5.jpg

 

Not much time was put into this recovery, most of the day was spent prospecting an area nearby. "Discovered" a freshly widened forest road (actually as wide as a good highway!) which perfectly exposes the mostly alluvial and reddish Geistthal-formation and the following clastic-marine Afling-formation for some 100 m thickness. Not much was found, but its a very, very impressive section. Here is my prospecting area (Römaskogel is in the lower left corner) and route (in blue) of that day. Red R indicate the last (highest) reddish beds:

Begehung_15052021_Geo.jpg.dd3837c3189c06e09cfabef54773fe6a.jpg

Begehung_15052021.thumb.jpg.a9e59465fb88e258e0b327c8bfc1333b.jpg

Still a lot to walk and observe during my next trip, especially to the east of the already explored area...:D. You never know what you will find. For example, #45 and #46 are small Trochactaeon indications. But these will be followed up next spring, when the green has gone again. Or not at all :zen:.

 

I only made one pic during prospecting, that of a thin (1-2 cm) seam of subbituminous coal withing silt-claystone, located between conglomerate beds (#47). Such occurrences are well-known in that area:

Punkt_47_15952921_klein_kompr.thumb.jpg.edc6f6f3269d0203fbb8290851bb8dc5.jpg

 

So, that was quite a typical day in the field for me: Some collecting at known sites, but more prospecting for new sites!

Thanks for looking and your interest!
Franz Bernhard

Edited by FranzBernhard
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Ludwigia

Hi Franz,

 

It's good to read in detail about how you go about with your prospecting excursions. It looks like you cover a lot of ground on days like this. Thanks for sharing.

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Wrangellian

Hey Franz... nice work. It seems like a lot of work putting this together, never mind the actual trip/digging!

Nice rudists... that one is bigger than I thought, once I saw the cm scale.

The site reminds me of the places in the B.C. Kootenays where we were taken to dig trilobites in Aug 2019. Such small outcrops, but fossiliferous enough to make digging worthwhile.

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historianmichael

It looks like a very successful dig. The complete rudists are very interesting. Hopefully you get the chance to get back out there and collect the remaining pieces to the one still stuck in the bed.

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FranzBernhard

Thanks for all your valued comments.

 

9 hours ago, Ludwigia said:

It looks like you cover a lot of ground on days like this

Sometimes more, sometimes less ;). You can easily overlook something if you are walking too fast. But this doesn´t really matter, people after me would also like to find something new ;).

 

7 hours ago, Wrangellian said:

It seems like a lot of work putting this together, never mind the actual trip/digging!

It is not that bad, I am used to it. At the moment, I am doing one trip each week, with a total of two hours of driving and 8-9 hours of prospecting and digging. Afterwards, I am making a report for my homepage mostly within one day, which takes about 1-2 hours for a first version without many pics. Later on, I am adding pics etc.

 

7 hours ago, Wrangellian said:

that one is bigger than I thought, once I saw the cm scale.

Yeah, its quite a big one. My local specialist found an about 30 cm long rudist in the pavement of the forest road very near to this outcrop. 

 

7 hours ago, Wrangellian said:

Such small outcrops

Everything is small here in Austria :D. I am surprised, that there are small outcrops in BC ;).

 

2 hours ago, historianmichael said:

It looks like a very successful dig. The complete rudists are very interesting. Hopefully you get the chance to get back out there and collect the remaining pieces to the one still stuck in the bed.

Yes, I achieved my goal in recovering the wanted rudist parts. I will not collect the tip of #4901 still sticking in the bed, too much effort for a too small piece. Next trip will be a pure prospecting trip. This nice, freshly widened forest road nearby - fresh outcrops for kilometers :D.

 

Franz Bernhard

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ColombianFossils

Thanks for posting, it's super interesting and I really enjoyed the sketches that accompanied the photos

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FranzBernhard
10 hours ago, ColombianFossils said:

Thanks for posting, it's super interesting

Thanks!

I liked your latest trip report very much. Its sooo different compared to my area. So many different landscapes to be seen around the world and so many different sites and fossils. And yet there is nearly always something familiar to me. In your case, these are the concretions. I have also lots of exactly the same type around me, unfortunately without any fossils in them and younger (Miocene).

Franz Bernhard

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ColombianFossils
8 minutes ago, FranzBernhard said:

Thanks!

I liked your latest trip report very much. Its sooo different compared to my area. So many different landscapes to be seen around the world and so many different sites and fossils. And yet there is nearly always something familiar to me. In your case, these are the concretions. I have also lots of exactly the same type around me, unfortunately without any fossils in them and younger (Miocene).

Franz Bernhard

Thanks Franz! Your post has really highlighted what makes a good report for me, next time I will be including a lot more details like you have done. 

 

It is amazing to see the differences across the world. One of my favourite things about this site is seeing all these beautiful and diverse places. You're so right in that there is always something familiar, even if so much is different. I look forward to your next post!

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FranzBernhard
Posted (edited)
14 minutes ago, ColombianFossils said:

I look forward to your next post!

I do not have much time doing this, but there are some older ones. That one

Trochactaeon - Kainach - 2020

is strongly related to this one, as the rudists were discovered in search for Trochactaeon, which occur in the same formation...

LOL!! Third pic shows Römaskogel hill from the other direction...

 

And a short visit to one of the Trochactaeon sites:

Trochactaeon - Kainach - Breitenbach-11

 

Franz Bernhard

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caterpillar

Great report, as always

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Wrangellian
20 hours ago, FranzBernhard said:

Everything is small here in Austria :D. I am surprised, that there are small outcrops in BC ;).

Well yes there are, and for the same reason: lots of overburden. :shakehead: If I want broad areas of exposed rock, I need to go to the US southwest! Or Morocco, or...

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Tidgy's Dad

Fascinating, detailed report with excellent description and photos. 

As always excellent.

Thank you. 

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