Shale is a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call mud.This composition places shale in a category of sedimentary rocks known as mudstones.hale is a rock composed mainly of clay-size mineral grains. These tiny grains are usually clay minerals such as illite, kaolinite and smectite. Shale usually contain other clay-size mineral particles such as quartz, chert and feldspar.
Extremely draught resistant Opuntia cactuses form arid shrub forests in the lowlands, particularly on the larger islands, like Santa Cruz. At higher elevations, the climate of the Galapagos Islands, Ecuador, is cooler and with more rainfall. As a result there is true forest on the higher mountains thanks to the cooling of the air as it is forced up. When the air cools off, the humidity in the air condenses, thus forming clouds.
An overview of the Galapagos Islands. They are produced by volcanic activity caused by magma upwelling at the Galapagos hotspot. Large craters can be seen where the most recent eruptions have occurred, including in 2005 at Sierra Negra near the south end of the largest island. Green to white indicates the coastline, outside this is below sea level.