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Bedrock geological map of Ireland. Layers of Upper Carboniferous sedimentary rocks, Loop Head, County Clare. The geology of Ireland consists of the study of the rock formations on the island of Ireland. It includes rocks from every age from Proterozoic to Holocene and a large variety of different rock types is represented.
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks).
The Minnesota Geological Survey has placed this image in the public domain with the request that credit be given to the Minnesota Geological Survey, University of Minnesota, and to the author(s) of the specific work. These images are available through the Minnesota Digital Library, "Minnesota Reflections".
The ages of more recent layers are calculated primarily by the study of fossils, which are remains of ancient life preserved in the rock. These occur consistently and so a theory is feasible. Most of the boundaries in recent geologic time coincide with extinctions (e.g., the dinosaurs) and with the appearances of new species (e.g., hominids).
The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon.
A geologic map or geological map is a special-purpose map made to show various geological features. Rock units or geologic strata are shown by color or symbols. Bedding planes and structural features such as faults , folds , are shown with strike and dip or trend and plunge symbols which give three-dimensional orientations features.
Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloging and comparing fossil floral and faunal assemblages.
1743 – Dr Christopher Packe produces a geological map of south-east England; 1746 – Jean-Étienne Guettard presents the first mineralogical map of France to the French Academy of Sciences. 1760 – John Michell suggests earthquakes are caused by one layer of rocks rubbing against another