Stromatolites from Steep Rock Lake

The Steep Rock Lake Limestone from northwestern Ontario, west of Lake Superior, is a stromatolitic limestone of Archean age (~2.9 billion years old). Stromatolites are calcareous structures created by cyanobacteria (blue-green algae). The photos below are of a specimen of the limestone that was cut into a thin slice approximately 1.5 mm thick. The photos were taken with a low power microscope. The fields of view are approximate. The black specks in the photos are small hunks of carbon. I speculate that the greenish gray blobs are original algal structures. Note that the color in the photomicrographs is greener than the actual specimen. The whole slab picture below gives a better indication of the specimen color. Also note that jpeg compression has introduced some artifacts into the images. I can provide copies of the original tiff images via emial to anyone who is interested. I would like to find someone with the proper equipment to search this specimen for fossil cell structures.


Field of View: 5mm	Field of View: 2.5mm	Field of View: 2.5mm	Field of View: 1.5mm

Below is a view of the whole specimen. The wavy pattern is characteristic of stromatolites.

Field of View: 25cm

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