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There was a lack of crop rotation, extensive drought & deep plowing of land, but did not occur in the Midwest
Many felsic layers & volcanic ash which is thick & contains gas under high pressure, explosive
Plume of upwelling basaltic magma deep within the mantle, arising far down in the astheopshere
Form when frothy basalt magma is ejected under high pressure from a narrow vent, producing tephra
Formed from preexisting rocks by intense heat & pressure, alter rock structure and chemical composition
Magma enters small, irregular branching fractures in surrounding rock & solidifies into a network
This is beneath the lithosphere, layer of soft, plastic rock in the mantle & tectonic plates are able to move due to relative weakness of this
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