Flora of Kwangtung and Hongkong/Geology
Geology.—The greater part of the surface of the coastal region consists of various igneous rocks, but chiefly of a kind of granite, which readily disintegrates under the action of the atmosphere. This granite is intermixed with harder and more resistant rock masses, which remain as gigantic boulders all over the granite mountains as the softer parts are washed away. In the interior and to a less extent on the coast, limestone formations, coal measures and tertiary sandstones occupy large areas. Alluvial deposits attain considerable dimensions only in the deltas of the East, West and North Rivers which coalesce to form the "Canton Delta" occupying approximately a triangle having three equal sides of about 100 miles each.