![continental continental convergent boundary continental continental convergent boundary](https://image3.slideserve.com/5989653/continental-oceanic-l.jpg)
As the ocean widened, the edge of ancient North America subsided, and a blanket of sedimentary layers buried the rift valleys and eroded mountain ranges.
![continental continental convergent boundary continental continental convergent boundary](https://261623jgd.weebly.com/uploads/4/2/9/4/42940785/2347526_orig.gif)
Sedimentary and volcanic layers that were deposited in the rift valleys are exposed in Shenandoah National Park and along the Blue Ridge Parkway. The resulting continental rift zone was much like today’s Basin and Range Province, with long mountain ranges separated by down-dropped valleys. Norton and Company, 298 pp., 2005, About 750 million years ago a very ancient supercontinent began to rip apart. Illustrations above modified from “Parks and Plates: The Geology of our National Parks, Monuments and Seashores,” by Robert J. The Blue Ridge Province is part of North America’s ancient continental margin, while the Valley and Ridge Province contains sedimentary layers of North America that were folded and faulted during the collision. Ancient ocean rocks are left behind as the Piedmont Province, along with a sliver of Africa that now lies beneath the Coastal Plain of Florida and offshore regions of Georgia and the Carolinas (purple). Later rifting opened the Atlantic Ocean, isolating the mountains as separate ranges on different continents.Ītlantic Ocean Opens. The Appalachian Mountains, along with the Caledonide Mountains in Greenland, the British Isles and Scandinavia, as well as the Atlas Mountains in northeastern Africa, are parts of a continental collision zone that formed 500 to 300 million years ago. Norton and Company, 298 pp., 2005, Tectonic Development of the Appalachian-Ouachita-Marathon Mountain Range Modified from “Parks and Plates: The Geology of our National Parks, Monuments and Seashores,” by Robert J. D-D’ is the line of the cross section showing in the tectonic provinces of the Appalachian Mountains. Acadia National Park is in the northern Appalachians in Maine. Hot Springs National Park is in the Ouachita Mountains, while the Marathon Mountains extend into Big Bend National Park. The Blue Ridge Parkway follows the crest of the mountains in Virginia and North Carolina, connecting Shenandoah and Great Smoky Mountains national parks. Four-letter codes refer to some of the National Park Service sites listed near the top of this page.
![continental continental convergent boundary continental continental convergent boundary](http://thenorthamericanplates.weebly.com/uploads/2/6/4/3/26433232/5656638_orig.png)
After 300 million years the mountains have eroded deeply and are covered in places by young sediments of the Atlantic and Gulf coastal plains. The Appalachian Mountains are part of a collisional mountain range that includes the Ouachita Mountains of Arkansas and Oklahoma, and the Marathon Mountains in west Texas. SHEN-Shenandoah National Park, Virginia. RUCA-Russell Cave National Monument, Alabama. OBED-Obed Wild and Scenic River, Tennessee.