opaseliöitä

Opaseliöitä, also known as guide fossils, are a type of fossil that is used to determine the relative age of sedimentary rock layers. These fossils are distinctive and are found in a limited range of rock layers, making them useful for correlation between different locations. Guide fossils are typically hard-shelled organisms, such as brachiopods, trilobites, and certain types of mollusks, that lived during specific geological periods. Their presence in a rock layer indicates that the layer was deposited during the time when the organism lived. By identifying guide fossils in different locations, geologists can match up rock layers and reconstruct the geological history of an area. This process is crucial for understanding the Earth's past environments and the evolution of life.