Fold model

This is a replica of the cliff along the Makinosaki coast, Oshika peninsula, Miyagi prefecture, which shows how regularly stacked sandstones and mudstones have become bent. The layers of strata were formed 150 million years ago during the Late Jurassic period. Sand and mud accumulated in the shallows crumbled and flowed down the submarine slope in an earthquake, and deposited horizontally in deeper waters. Repeated occurrences of a series of strata from white sand to black mud accumulating at once resulted in the formation of alternating beds of sandstone and mudstone several thousand meters thick. 110 million years ago, in the middle Cretaceous, east-west compression caused the strata to bend, resulting in the formation of a geological structure called a “fold.” Such geological structures occur on the continent where the oceanic plates subduct beneath the continental plates , or where continents collide with one another like the Alps and the Himalaya mountains. A fold is a record of past crustal movements.