Laurentia noun. Save Word. Definition of Laurentia. Many of the rocks there were produced by a huge collision of tectonic plates about million years ago, called the tectonic orogeny, that sent an arc of islands crashing into the eastern coast of North America or, more correctly, Laurentia. Love words? Start your free trial today and get unlimited access to America's largest dictionary, with: More than , words that aren't in our free dictionary Expanded definitions, etymologies, and usage notes Advanced search features Ad free!
Join Our Free Trial Now! First Known Use of Laurentia , in the meaning defined above. Keep scrolling for more. Learn More About Laurentia. Time Traveler for Laurentia The first known use of Laurentia was in See more words from the same year.
Over the hundreds of millions of years, Laurentia's shape has changed slightly, due to bumping into other cratons; volcanic activity, especially large igneous provinces, which may be extruded over the course of a million years; and sedimentary accretion.
At the margins of the continents are where much of the mountain-building takes place, due to pressure between colliding cratons. The Laurentian craton has mountain ranges on both margins — including the Sierra Nevadas in the west and the Appalachians in the east.
Part of the reason the name "Laurentia" is necessary is that the continent has been in various different configurations throughout its history, and is not necessarily always "north" of anything, making "North America" inappropriate. Laurentia has been a component of the supercontinents Kenorland, Nena, Columbia, Rodinia, Protolaurasia, Pannotia, Euramerica, Pangaea, Laurasia, and the current minor supercontinent , America.
For tens of millions of years, during the Cretaceous period , Laurentia was divided down the middle by the Western Interior Seaway. Various marine fossils can be found in the central USA and Canada because of this.
Some sources list it as winter hardy into zone 7 while others say it is only hardy in frost-free areas. Where hardy it has a more sprawling habit while young but becomes more upright once the woody base forms.
Flowers are produced singly from leaf axils and are to an inch and a half across, 5-lobed and borne at the end of an inch long slender tube. Most forms are a soft sky blue but purple, pink and white selections are available. Plants bloom from seed in 4 months with transplants not set out until the threat of frost is past. Blue star was grown during the 19 th century but by the early years of the 20 th century seems to have fallen by the wayside.
It reappeared in the s with the new plant craze that swept across the garden world. Blue Star should not be confused with Blue Star Creeper Isotoma fluviatilis , a related plant that grows only an inch tall and is covered with quarter inch blue flowers during the spring and summer.
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