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In 1834 Guillermo Schulz produced the first geological map in Spain, a 1:400 000 scale map of the area of Galicia. [49] the first geological map of Spain drawn by Joaquín Ezquerra del Bayo. Charles Lyell visited Spain in the summer of 1830 and also in the winter of 1853. Lyell's visit to the Pyrenees led him to study the orogeny that produced ...
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).
Each period is marked below the era bar on top of its subdivided epochs and stages. Each stage is assigned an age in mya , an acronym for million years ago, which is the age at which it began. Most of these ages are derived from astronomical cycles in sediments, magnetic data, biostratigraphic data, and radiometric dating methods.
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).
Geologic time is the timescale used to calculate dates in the planet's geologic history from its origin (currently estimated to have been some 4,600 million years ago) to the present day. Radiometric dating measures the steady decay of radioactive elements in an object to determine its age. It is used to calculate dates for the older part of ...
In stratigraphy, paleontology, geology, and geobiology, an erathem is the total stratigraphic unit deposited during a certain corresponding span of time during an era in the geologic timescale.
The "exceptional" 130-million-year-old fossilized remains of a pregnant ichthyosaur with several fully intact embryos have been unearthed in Chile, a first-of-its-kind prehistoric discovery on the ...
The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as the time between c. 129,000 and c ...