Into a bit of the Czech Cretaceous

June 14th, 2019

Beroun, Czech Republic — Today the International Bryozoology Association pre-conference field party visited a fascinating quarry near Chrtníky, Czech Republic. Ordovician diabase is mined here for road gravel and other industrial uses. This rock was uplifted and exposed during the Mesozoic. In the Late Cretaceous, the sea flooded into valleys excised into the diabase, creating long, narrow seaways with steep cliffs of diabase. Cretaceous marine marls filled the valleys, enclosing lots of fossils.

One of the Cretaceous valleys can be seen in this quarry wall as a brown marl fill.

This is a small valley with whitish Cretaceous sediment between diabase walls.

The left part of the hammer head supports a calcareous sponge. The right shows a micritic limestone with a diabase clast that was eroded from the cliff side.

Earlier in the day we explored the Czech city of Olomouc, where we had spent the night. The statuary is magnificent, as seen here in the city square.

Hercules with his club.

We can’t forget what a nightmare this city was, though, for its Jews during World War II. Olomouc was dominated by Germans before and during the war. Almost all the Olomouc Jews were deported to concentration camps, where most were killed. Small plaques like these are set among the cobblestones, marking the former homes of Jews and their deportation dates.

 

2 Responses to “Into a bit of the Czech Cretaceous”

  1. Alex Crawfordon 26 Jun 2019 at 9:16 am

    Looks like a good trip, Mark! I really like the quarry shot of the marl-filled valley. Is that vertically continuous up to the next level of the quarry (i.e., any idea how deep in total those valleys would have been)? What you describe sounds similar to a fjord.

  2. Mark Wilsonon 26 Jun 2019 at 9:21 am

    Hi Alex: Those Cretaceous valleys cut into the diabase are indeed amazing. It is impossible in this exposure to set an upper limit, but some valleys are tens of meters deep. Some do look fjord-like; others have sharp v-shaped bases.

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