Wrangellia Terrane, Large igneous province in Alaska, United States
Wrangellia Terrane is a fragment of Earth's crust in south-central Alaska that contains thick flood basalt deposits and volcanic rock formations from the Late Triassic. The rocks are exposed across the Wrangell Mountains, where layered geological sections can be seen on the surface.
This crustal fragment originally formed near what is now Baja California and drifted northward over millions of years before joining the North American continent during the Cretaceous period. The volcanic rocks within it date to the Late Triassic, when intense eruptions built up the thick basalt layers seen today.
The exposed rock layers in the Wrangell Mountains draw geologists from around the world who come to study ancient volcanic processes up close. Few places on Earth offer such accessible and well-exposed sections of flood basalt from such a distant geological era.
The most accessible rock exposures are found in the Wrangell Mountains, where some areas can be reached on foot with proper hiking gear. The terrain is steep and remote, so planning the route in advance and going with an experienced guide is strongly advisable.
Although Wrangellia is now firmly part of Alaska, its rocks contain fossils of tropical marine animals that could only have lived in a much warmer ocean far to the south. These fossils are a direct record of the long journey this piece of crust made before it arrived at its current position.
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