Search results
Results from the WOW.Com Content Network
The Hirnantian glaciation, also known as the Andean-Saharan glaciation, Early Paleozoic Ice Age (EPIA), [1] the Early Paleozoic Icehouse, [2] the Late Ordovician glaciation, or the end-Ordovician glaciation, occurred during the Paleozoic from approximately 460 Ma to around 420 Ma, during the Late Ordovician and the Silurian period.
Ice caps formed on the southern supercontinent Gondwana as it drifted over the South Pole. Correlating rock strata have been detected in Late Ordovician rock strata of North Africa and then-adjacent northeastern South America, which were south-polar locations at the time.
In fact, the Hirnantian (also known as the End Ordovician and the Ordovician-Silurian) mass extinction event represents the second largest such event in geologic history. Approximately 85% of marine (sea-dwelling) species died. Only the End-Permian mass extinction was larger. Unlike many smaller extinction events, however, the long-term ...
There is evidence of glaciers during the Hirnantian on the land we now know as Africa and South America, which were near the South Pole at the time, facilitating the formation of the ice caps of the Hirnantian glaciation. As with North America and Europe, Gondwana was largely covered with shallow seas during the Ordovician. Shallow clear waters ...
The Late Ordovician is the third and final epoch of the Ordovician period, lasting 15.1 million years and spanning from around 458.2 to 443.1 million years ago. [ 4 ] [ 5 ] The rocks associated with this epoch are referred to as the Upper Ordovician Series.
The Quaternary saw repeated glaciations of the Lake District area with the development of an ice cap, although the current landscape is the result of the Last glacial period, which occurred over the period 115,000 to 11,700 years ago. As the Lake District was an upland area it was unaffected by the main British-Irish ice sheet, which flowed ...
Throughout Earth's climate history (Paleoclimate) its climate has fluctuated between two primary states: greenhouse and icehouse Earth. [1] Both climate states last for millions of years and should not be confused with the much smaller glacial and interglacial periods, which occur as alternating phases within an icehouse period (known as an ice age) and tend to last less than one million years ...
The melting of the ice may have presented many new opportunities for diversification, and may indeed have driven the rapid evolution which took place at the end of the Cryogenian period. Global ice cover, if it existed, may—in concert with geothermal heating—have led to a lively, well mixed ocean with great vertical convective circulation ...