Answer:
D
Explanation:
Isostasy is the condition of equilibrium that results in the displacement of the mantle by the continental and oceanic crust.
Isostasy is also known as standstill. It is the condition that makes earth's crust and mantle to float dependin on the thickness of the roots.
Answer:
river system, sandy beach or delta, plant rich swamp
Explanation:
The upper part of the stratigraphic horizon consists of Sandstone, mudstone, dust cracks with plant fossils and most significantly the coal unit. This records is quite sufficient to factor out the surroundings of deposition and prediction of supply rock. The lowermost a part of this horizon is consists of coal layers so the environment must be swampy in nature. Mud Cracks containing fossils pf plant constitute the coal are form not inside the in-situ mode they are from in ex-situ mode that means the coal isn't the autochthonous origin however are allochthonous in origin. Plant cloth comes from a different location and deposited in this zone and people not be triumphant a good decreasing situation remains as a fossil inside the dust cracks.
Mudstone include Silt and Clay which are very excellent grain particles. This mudstone is deposited in a totally low electricity circumstance of the muddy part of the ocean. This low strength condition isn't maintained for a long term and there may be a sluggish fluctuation of surroundings and high power condition cause deposition of the sandstone. Sandstone contains a number of small cross mattress which represents a beach surroundings. As a selected region document with the mud crack it is essential to say that this unique time complements the formation of coal just beneath the subsurface because the upper component is exposed to the surface.
So those are the geological history of the Upper part of the Stratigraphic horizon
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