Sedimentary rocks -are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution.
Metamorphic rocks-arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure (1500 bars), causing profound physical and/or chemical change.
Igneous- (derived from the Latin word ignis meaning fire) is one of the three main rocktypes, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava.
Stratification-is a system or formation of layers, classes, or categories.Stratification is used to describe a particular way of arranging seeds while planting, as well as the geological layers of rocks.
This picture shows the stratification in a rock
When they find a fossil they etermine how old the fossil is and that is how old the rock layer is.
Usually what causes the horizontal sedimentary layers are usually natural causes.
Living organisms shape land forms by digging or starting trails also the roots of plants start cracks in rocks.