What was the big continent called

The Earth through time The Earth through time. Page Content. Ireland's geology formed before, after and during the time of Pangaea, and our oldest rocks are possibly from the time of an earlier supercontinent. To learn how Ireland got to where it is today see Geology of Ireland in the Education section. Tile 1 Description. Tile 2 Description. Tile 3 Description. Tile 4 Description. Tile 5 Description. Tile 6 Description. Tile 7 Description. Tile 8 Description. Tile 9 Description.

Tile 10 Description. Tile 11 Description. Tile 12 Description. Tile 13 Description. Tile 14 Description. Most of this period, however, was a notably quiet one, accumulating the quartz-rich sandstone geologists have named the Gypsy and Addy Formations and limestone of the Metalline Formation.

In northeast Washington, these are economically important sources of raw materials. The layers have since been pushed to nearly vertical. Photo: Michael Miller.

As the Pacific Northwest comfortably passed through the Paleozoic Era, it witnessed a veritable explosion of life. Off its shores, most of the major groups of animals first appear in the fossil record in the Cambrian Period some million years ago. The first fish appeared in the Ordovician Period, perhaps million years ago.

The first plants invaded the land in the Silurian Period, about million years ago. The earliest amphibians showed up in the Devonian Period, perhaps million years ago, while the first true reptiles arrived on the scene in the Carboniferous Period about million years ago. Rocks representing each of these time periods are preserved in Eastern Washington along the ancient marine shelf of Rodinia. Somewhere around the Devonian Period some million years ago, a major change occurred along the continental margin.

The oceanic plate, previously fixed to the continental margin, plunged underneath the continent along a new subduction zone. This ended a million year history as a passive continental margin. Along the coast in Eastern Washington and British Columbia, that newly-subducting plate gave rise to a volcanic arc which developed inland, intruding granite-type plutons into continental sediments which had been accumulating for over a billion years.

This volcanic arc appears to have lasted from about to million years ago. The continental fragments dispersed during the breakup of Rodinia slowly began to come back together during the latter half of the Paleozoic Era. The intermittent episodes of subduction along the west coast of North America during this time probably record the jostling among plates as they reorganized.

The assembly of the giant continent Pangaea probably caused large-scale climatic disruption and a collapse of many terrestrial and oceanic ecosystems. In this new setting, much of North America reverted to desert. In part, these changes may have contributed to a great mass extinction that occurred million years ago at the end of the Permian Period. Literally 90 percent of all species of life went extinct. This was the largest extinction event in the history of life on Earth — greater even than the extinction of dinosaurs 65 million years ago.

The ultimate cause of this great extinction remains a subject of considerable debate. This was the largest extinction event in the history of life on Earth — greater even than the extinction of the dinosaurs 65 million years ago. Pangaea persisted over much of the Permian and Triassic periods, a span of some million years. Over this period, the western shoreline curved through western Idaho. Sediment — mud, silt, sand and calcium carbonate -- accumulated in thick layers beneath shallow seas along the continental shelf of Eastern Washington.

The construction Pangaea left much of present North America as a windswept desert. Coupled with the widespread extinction of life on both land and water, it presented a pretty bleak picture. Conditions improved measurably in Triassic Period, and life recovering to a significant degree. From the survivors of the Permian-Triassic extinction, life gave rise to the first true Dinosaurs and the earliest mammals.

On the ancient supercontinent of Pangaea, things were finally starting to look better. All good things come to an end. This quiet and comfortable arrangement in the Pacific Northwest ended a little more than million years ago, as Pangaea began to break apart. About million years ago, Pangaea began to rupture to form the Atlantic Ocean.

The breakup began as a rift between the modern western and eastern hemispheres. The rift evolved into a spreading center that literally pushed the two hemispheres apart. Early stage in the breakup of Pangaea million years ago.

The suture between North and South America. Note that much of the Pacific. If you study the maps on this page, you will see that the Atlantic Ocean is getting wider as a result of the plate movement.

Also, the Pacific Ocean is closing. A new supercontinent might form when the Pacific Ocean completely closes and the continents surrounding it converge. The current continent of Eurasia could be considered a supercontinent.

The Ural Mountains separate Europe from Asia and mark a line of compression and deformation where the two continents crushed into one another. Maps on this page by USGS. What is the San Andreas Fault? How did the Hawaiian Islands Form? Find Other Topics on Geology. Maps Volcanoes World Maps.