Search results
Results From The WOW.Com Content Network
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. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most ...
English: The geologic time scale proportionally represented as a log-spiral. Some key events in Earth's history are marked on the diagram, including major extinction events, global scale glaciations, the inanition of permanent atmospheric oxygen, the formation of the moon, and the formation of Earth's magnetic field.
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 ICS International Chronostratigraphic Chart" (PDF). 2017/02. pp. 199–204. U.S. Geological Survey Geologic Names Committee. "Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units" (PDF). USGS. Fact Sheet 2007-3015
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).
Download as PDF; Printable version; In other projects ... (video games, interactive websites ... Geologic time scale ...
Because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, this task becomes more difficult as one goes farther back in time. Before 630 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as "Global Standard Stratigraphic Ages" (GSSAs).
The Geologic Calendar is a scale in which the geological timespan of the Earth is mapped onto a calendrical year; that is to say, the day one of the Earth took place on a geologic January 1 at precisely midnight, and today's date and time is December 31 at midnight. [1]