Wooster Geologists

KAUGATUMA, SAAREMAA, ESTONIA–It is always an important moment for a Wooster geology research team when it identifies its final student independent study project. Today Palmer Shonk found his. There is a remarkable exposure of a high-energy deposit in the Aigu Beds (Kaugatuma Stage, Upper Silurian) on the Sõrve Peninsula of southwestern Saaremaa island. These rocks have spectacular crinoid materials, including elaborate holdfasts, along with stromatoporoids, bryozoans and brachiopods. The sediments still retain their original dune bedding forms showing the high energy conditions under which they were deposited.

Palmer and Rob at the Kaugatuma locality (N58.12409°, E22.19375°). I probably shouldn't point out again the spectacular weather. That would be like bragging.

Crinoid fragments (left) and well-preserved stromatoporoids (right) at the Kaugatuma locality.

Palmer’s job will be to understand the original organisms and the environments in which they lived and died (a paleocommunity study) as well as the means by which the remains were redistributed and preserved (a taphonomy study). It is exciting material which will make an excellent project.

At the end of the day we said good-bye to our generous and thoughtful Estonian hosts Olev and Ingrid Vinn. We are on our own now in Estonia, but they’ve trained us well. They left us at the marvelous Kaali Meteorite Craters, estimated to be about 7500 years old.

The main Kaali meteorite crater. On the far side of the pond you may see a spot of blue. That is Rob McConnell performing his job as a scale very well.

The Estonia team at Panga Cliff on the northern coast of Saaremaa (N58.55321°, E22.28577°). Note the gorgeous weather.

KURESSAARE, SAAREMAA ISLAND, ESTONIA–It was an exquisitely crystalline day of blue and gray here with clear skies, a sparkling sea, and beautiful limestones just waiting for the touch of our hammers. We continued to explore the Lower Silurian (Wenlock) of the Saaremaa coast, fascinated with the numbers and varieties of fossils we found. These rocks have been carefully cataloged by biostratigraphers, so we know exactly how they fit into the larger geological picture in time and space. This gives us the opportunity to concentrate on the paleontological and sedimentological questions before us.

There is a distinctive and widespread horizon in these rocks of stromatoporoids, a kind of calcareous sponge which built on the shallow seafloor stony mounds up to the size of large cabbages. These stromatoporoids were bored by at least two kinds of worm-like organisms, and then encrusted by corals and bryozoans. Some corals even grew inside the skeleton of the sponges in a kind of symbiosis. There are many riddles here about how these fossils are preserved, how the community was structured, and what sort of environment it flourished and was eventually buried in. This will be the basis of Rob McConnell’s Independent Study thesis. We will all return to this site in a few days to do the detailed work of measuring, counting and collecting.

Rob and Palmer closely examine stromatoporoid fossils found in place at the foot of the Liiva Cliff on the northern coast of Saaremaa (N58.57553°, E22.36821°).

Rob, by the way, was reunited with his luggage late this afternoon, so he’s a happy man.

Rob McConnell and Palmer Shonk at the Uugu Cliff locality, Muhu Island, Estonia (N58.67136°, E23.23988°). The blue Baltic Sea is in the background.

KURESSAARE, SAAREMAA ISLAND, ESTONIA–Like the Iceland team, our first full field day in Estonia was spent in reconnaissance on the islands of Muhu and Saaremaa. We visited an abandoned quarry just north of Koguva to examine Lower Silurian (Wenlock) dolomitic mud mounds and limestones near Koguva, and then went to the Uugu Cliff which exposes a similar sequence but a little younger within the Silurian. Caves are found high in the cliff which were cut by waves of Ancylus Lake, a freshwater precursor of the Baltic Sea between 9500 and 8000 BCE. There are also trenches on the top of the bluffs dug by Tsarist Russian soldiers during World War I.

Later in the afternoon we collected Wenlockian fossils at the seaside Paramaja Cliff which had been weathered out of their rock matrices by the waves. We found a good collection of rhynchonellid brachiopods, strophomenid brachiopods, rugose corals, tabulate corals, encrinurid trilobites, crinoid stems, nautiloids, and cornulitids. (Like music, isn’t it?)

Palmer and Rob in the traditional fossil collecting position at Paramaja Cliff (N58.61531°, E22.89790°). Palmer was not particularly happy about the long walk through the stinging nettles.

Tomorrow we continue our survey of Silurian localities. The weather could not be better. (It sure beats sleet in Svalbard and mosquitoes in Russia, I must say!) Rob’s luggage is scheduled to arrive at our Kuressaare hotel in the afternoon, so we’ll finally have our full kit.