<P> In the southern Rocky Mountains, near present - day Colorado, these ancestral rocks were disturbed by mountain building approximately 300 Ma, during the Pennsylvanian . This mountain - building produced the Ancestral Rocky Mountains . They consisted largely of Precambrian metamorphic rock forced upward through layers of the limestone laid down in the shallow sea . The mountains eroded throughout the late Paleozoic and early Mesozoic, leaving extensive deposits of sedimentary rock . </P> <P> Terranes began colliding with the western edge of North America in the Mississippian (approximately 350 million years ago), causing the Antler orogeny . For 270 million years, the focus of the effects of plate collisions were near the edge of the North American plate boundary, far to the west of the Rocky Mountain region . It was not until 80 Ma these effects began reaching the Rockies . </P> <P> The current Rocky Mountains arose in the Laramide orogeny from between 80 and 55 Ma . For the Canadian Rockies, the mountain building is analogous to pushing a rug on a hardwood floor: the rug bunches up and forms wrinkles (mountains). In Canada, the terranes and subduction are the foot pushing the rug, the ancestral rocks are the rug, and the Canadian Shield in the middle of the continent is the hardwood floor . </P> <P> Further south, an unusual subduction may have caused the growth of the Rocky Mountains in the United States, where the Farallon plate dove at a shallow angle below the North American plate . This low angle moved the focus of melting and mountain building much farther inland than the normal 200 to 300 miles (300 to 500 km). Scientists hypothesize that the shallow angle of the subducting plate increased the friction and other interactions with the thick continental mass above it . Tremendous thrusts piled sheets of crust on top of each other, building the broad, high Rocky Mountain range . </P>

What is the exact location of the rocky mountains