CurrentThis gigantic slab of rippled sandstone is found in the Świętokrzyskie Mountains (also named

CurrentThis gigantic slab of rippled sandstone is found in the Świętokrzyskie Mountains (also named the Holy Cross Mountains) in central Poland. The rocks are Cambrian-aged sandstones, originally deposited in nearshore-tidal settings just over 500 million years ago. They were deposited on a sliver of crust probably rifted from the larger Gondwana supercontinent. Later, during the Ordovician this crustal sequence would run into and accrete to the Baltica Craton, a piece of stable crust now found making up most of Scandinavia. As sea level and sedimentation rates changed, sandstones marched in and out, creating a thick sequence of sedimentary rocks that in some cases has given rise to oil and gas deposits. The spectacular preservation of these ripples implies that the sand was first moved into the ripples by a flowing current and that the rippled surface was rapidly buried by another layer of sediment, entombing it for hundreds of millions of years.The sediments were buried to depths of hundreds of meters in the ground where the Earth’s natural heat warmed them to over 100°C. This heat allowed the grains to be lithified into solid sandstones. They were then uplifted back to the surface during the later Caledonian and Hercynian orogenies.-JBBImage credit: http://bit.ly/290BJGDReferences:https://gq.pgi.gov.pl/article/download/7399/6049http://www.sciencedirect.com/science/article/pii/S0012821X00003125http://www.mindat.org/loc-69351.htmlhttp://bit.ly/28TdGoX -- source link

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