Glacier National Park, MT is the resting place of some of the oldest and best preserved layers of the early earth. Due to tectonic pressures a long time ago, a great upheaval of old Precambrian rock was repositioned on top of younger Cretaceous rock. Geologists come to Glacier National Park to study this Lewis Thrust Fault, also called the Lewis Overthrust. This geological phenomenon is a lesser-known attraction to Glacier National Park. Great ways to get up close and personal with these finely preserved formations is to hike to a number of places on the Glacier National Park trails, take a full day whitewater rafting trip and suggest to start as high up river as possible or take a guided horseback trip. Even a leisure drive up the Going-to-the-Sun Road will give you clues. For information on ideal in-park lodging, raft trips, guided hiking or horseback trips in Glacier National Park contact National Park Reservations for all your travel arrangements.

In the early days of planet earth's life, there was a great sea where Glacier National Park, MT is today. It is now referred to as the Belton Sea. It was full of six different species of blue-green algae over the expansive time period of this inland sea. These tiny lifeforms are responsible for building our oxygenated atmosphere along with early lichens. The fossils of these tiny lifeforms and the earth surrounding the fossils can tell us a lot about the events and environment during that time before the gorgeous and rugged mountains of Glacier National Park were fully formed. These ancient layers and formations were not just laying on the surface to be found in pristine conditions. These layers were thrust to the surface again, hundreds of millions of years later after being protected deep within the earth. The layers were discovered in a rarely pristine condition only mildly effected by the elements. We can thank the Lewis Overthrust for that boost. A great example of the Lewis Overthrust is Chief Mountain in Glacier National Park, MT. Tall and isolated, the elements of time have stripped away the surrounding earth above what is now Chief Mountain and around it, to reveal this extremely old and extremely special phenomenon.

So as the tectonic plates of earth rearranged, stressed, fractured and changed faces over time in order to start building the Rocky Mountains, there was a thrusting action taking place up near where Glacier National Park, MT is today. As a layer of earth was fractured, part of itself moved up on top of another part of itself. Think of this like Neapolitan ice cream. First there were three layers of strawberry, vanilla and chocolate. The Strawberry was the newest, vanilla in the middle and the chocolate was the oldest and was originally over three miles below the earth's surface before the thrusting action. After this thrust fault was done with it, there are now six layers; two layers stacked on top of each other in the pattern of new, medium, old, new, medium, old. As the elements of time wore down the top strawberry and vanilla layers, there is this extremely old chocolate layer sitting upon the three layers below it of young, medium and old that is still over three miles down. This old (chocolate) layer is anywhere from 1,300 -1,500 million years older than then new strawberry layer below it. This is what exposed these old, Precambrian layers with detailed, greatly preserved simple lifeforms that give way to what the earth was like before it became Glacier National Park.

Other examples of these rock layers outside of Glacier National Park, in areas such as the Himalaya Mountains and the Andes, have been exposed to the elements of sun, water, wind, vegetation, ice and mountain building. This makes them hard to study and learn from. In Glacier National Park, MT, scientists are able to look at pristinely preserved ancient sedimentary rock layers up close, without confusion. The formation of ripple marks from the inland sea, mud cracks, oolites, raindrop marks, and of course, the six species of algae can be seen from many areas in the park. One great way is to take a whitewater raft trip. Early in the year is when full day trips start farther upstream. It is these upper Middle Fork of the Flathead River trips that will give the very best examples of these sedimentary clues. Even a half-day whitewater rafting trip will demonstrate this phenomenon. These formations are visible from the many miles of trails in Glacier National Park as well. Guided hikes are available as well as guided horseback adventures into either Glacier National Park, or the Bob Marshall Wilderness Complex. This Lewis Overthrust formation is 50 miles of overlapped earth from west in Glacier National Park, east into the Bob Marshall. If you are interested in Glacier National Park, MT and also interested in geology and seeing the formations that make Glacier National Park revered in the geology world, call National Park Reservations where we can arrange the most ideal lodging and activities to correlate to your goals.