from what time period are most of the rocks in glacier national park
Glacier National Park (U.S.) The rocks found in the park are primarily sedimentary rocks of the Belt Supergroup. They were deposited in shallow seas over 1.6 billion to 800 million years ago. During the formation of the Rocky Mountains 170 million years ago, one region of rocks now known as the Lewis Overthrust was forced eastward 50 miles (80 km). This overthrust was several miles (kilometers) thick and hundreds of miles (kilometers) long.[45] This resulted in older rocks being displaced over newer ones, so the overlying Proterozoic rocks are between 1.4 and 1.5 billion years older than Cretaceous age rocks they now rest on.[45][46]