Discordance Between Mesozoic and Paleozoic Rock Layers

March 07, 2017

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Photographer: Petr Hykš
Summary Author: Petr Hykš

What is discordance in geology? It can be very well explained by the above photo, taken at the Hády limestone quarry in Brno, Czech Republic. Discordance, also known as an unconformity, is a border between two sedimentary events that are usually separated by a long time interval. The older sediments are generally folded and or eroded, while the younger sediments lay nearly horizontally. Here, the red line is the border between the younger Mesozoic (Jurassic) strata, above the red line, and the older Paleozoic (Devonian) limestone, lying above the yellow line. The discordance is parallel to the younger sediments.

This situation can, and will, change in time. In hundred millions of years, the Jurassic sediments will be folded too, and there will be a new discordance with younger, horizontal sediments. Photo taken on March 27, 2016.  

Photo Details: Camera Maker: SONY; Camera Model: DSC-W730; Focal Length: 4.5mm; Aperture: ƒ/8.0; Exposure Time: 0.0050 s (1/200); ISO equiv: 80.