A landform is a feature on the Earth's surface that is part of the terrain. Mountains, hills, plateaus, and plains are the four major types of landforms. Minor landforms include buttes, canyons, valleys, and basins. Tectonic plate movement under the Earth can create landforms by pushing up mountains and hills.
A plain is nothing but a low-lying relatively flat land surface with very gentle slope and minimum local relief. About 55% of the earth's land surface is occupied by plains. Most of the plain have been formed by deposition of sediments brought down by rivers.
Plateaus are elevated flatlands. In other words, it is flat land which is standing high above the surrounding area. Furthermore, they may have one or more sides with steep slopes. Also, depending upon the plateau, their height varies from a few hundred meters to several thousand meters.
Scientists collect information that allows them to make evolutionary connections between organisms. Similar to detective work, scientists must use evidence to uncover the facts. In the case of phylogeny, evolutionary investigations focus on two types of evidence: morphologic (form and function) and genetic.
Prokaryotes were the first forms of life on Earth long before simple multicellular life appeared because of their ability to withstand extreme conditions. It is believed that the first living forms were bacteria combined with archaea in the microbial mat (multi-layered sheet).
