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Chert

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Copyright © Jamison K. Brizendine
 
 
minID: 2RR-V32

Chert

Copyright © Jamison K. Brizendine  - This image is copyrighted. Unauthorized reproduction prohibited.
Dimensions: 5 cm x 3.7 cm x 1.3 cm

This is a miniature specimen of chert from the Barrett Paving Materials Quarry (Middleboro Stone Quarry), Richmond, Indiana, United States. The chert from this quarry are identified as part of the Silurian Brassfield Formation (~430 ma). The chert from this quarry is typically white to a gray color, nodular in shape, and is typically stained by iron oxides. The limestone and dolostones found in this quarry are typically used for aggregate (Parker 2006).

It is interesting to note that the quarry’s rocks differ greatly from the Upper Ordovician rocks found south of this quarry. The Upper Ordovician rocks show a great diversity of marine fossils, while the exposed Silurian rocks in this quarry show a distinct lack of fossils. It is theorized that a mass extinction even occurred between the two periods, but the possible cause is still unknown and hotly debated. The leading theory suggests that increased volcanic activity may be a possible cause to the extinction event (Young et al. 2007).

I collected this specimen on November 23, 2004 on an Earlham College sedimentology field trip. I mostly collected reference specimens from this quarry for a field trip write up. This was one of these specimens.

The specimen is approximately 5 x 3.7 x 1.3 cm

Jamison K. Brizendine specimen and photo

References Cited:

Parker, R., 2006, From the tropics to the tundra: Snapshots of the Lower Paleozoic and the Quaternary near Richmond, Indiana, in Professional Geologists of Indiana, November 4, 2006, Field Trip Guidebook: Richmond, Indiana, Earlham College Geosciences, 16 p.

Young, S., Saltzman, M., Foland, K., Linder, J., and L. Kump, 2009, A major drop in seawater 87Sr/86Sr during the Middle Ordovician (Darriwilian): Links to volcanism and climate?: Geology, v. 37 (10), Geological Society of America, p. 951-954.

Collected: 2004

This photo has been shown 549 times
Photo added:23rd Sep 2014
Dimensions:1301x1225px (1.59 megapixels)
Date/Time of Photo:5th Jan 2007 21:45:09
Camera:KODAK Z1275 ZOOM
Exposure time:1/50s
Aperture:f/3.8
Focal Length:22mm
Focal Length (35mm film equivalent):105mm
ISO speed:64
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