Friday, June 11, 2010


In solidarity with my fellow bloggers at Views of the Mahantango and Swimming the Ordovician Seas, I present a post on local stromatoporoids.

Looking at some large pieces of Silurian Period Louisville Limestone that reside in the flower bed, revealed quite a bit of biodiversity.  A chunk of limestone appears to contain the partially eroded remains of a sponge.

Part of the rock contains Halysites coral which dates it to the Silurian Period.

A Silurian brachiopod with crinoid stem pieces with a Halysites coral in the background in another section of the rock.

This tube coral is somewhat of a mystery. It looks like a Devonian coral but since this rock has the Silurian Period index fossil Halysites this must be Louisville Limestone.

Close up of Silurian Period brachiopod shown earlier, that might be a Sphaerirhynchia.

These next two pictures are of a Silurian Period sponge fossil with a lot of layers.  It is almost 20 cm wide.  Fossil found in Jefferson County, Kentucky.

This next type of stromatoporoid is one of my favorites. It is a mounding sponge and the shapes sometimes remind me a scoop of chocolate ice cream.
Mounding Sponge Fossil
Louisville Limestone
Silurian Period - Jefferson County, Kentucky

The Falls of the Ohio State Park Visitor Interpretation Center has a nice display on these ancient sponge creatures.  Paraphrasing it, the Jeffersonville Limestone found at the park has about 30 identified species of calcium carbonate fossils.  The creatures typically are found in sheet, hemispherical or mound-like shapes.  Colonies could range from 30-250 cm in size.  It is thought these sponges existed in warm, clear, shallow seas.  The fossils might be related to modern sclerosponges.

Hindia sphaeroidalis Stromatoporid
Devonian Period
Jeffersonville Limestone - Louisville, Kentucky

Matting Sponge on Heliophyllum Coral
Devonian Period
Beechwood Limestone - Clark County, Indiana

Learn more about stromatoporoids at the Kentucky Geological Survey web page.