Important geological concepts were established as naturalists began studying the rock formations of the Alps in the 18th century. In the mid-19th century the now defunct theory of geosynclines was used to explain the presence of "folded" mountain chains but by the mid-20th century the theory of plate tectonics became widely accepted.
Who began studying the rock formations of the Alps When did the studying of rock formations begin in the Alps? What was used in the mid-19th century to explain the presence of "folded" mountain chains?  What theory was more widely accepted by the mid-20th century? 