Below: Here are a couple more photos of concretions along the White Cliffs of the Missouri. This 47-mile stretch is one of the premier canoe/kayak trips in the USA. CLICK HERE for an account of the 3-day journey (lots of photos). Here is another link to more information about concretions, including a short video (does not open on many mobile devices).
These are fossils of stromatolites that can be seen along one of the most popular trails in Glacier Park. CLICK HERE to see more photos taken along the Highline Trail.
Glacier Park is made almost entirely of rocks from the Belt Formation (aka "The Belt Supergroup") - layer upon layer of sandstones, shales, and carbonates from the late Precambrian Era. At that time there were no organisms with bones or shells, so stromatolites like those shown in the photo, are the only fossils that can be found in Glacier Park.
Stromatolites are mound-like, multi-layered colonies of algae (blue-green algae; aka cyanobacteria), and their formation has much to do with the way they change the chemistry of the shallow water they live in. The photosynthetic cyanobacteria remove carbon dioxide from the surrounding water, causing calcium carbonate to precipitate onto their slimy, mat-like colonies. Calcium carbonate, along with grains of sediment (silt, etc.), stick to the bio-film layer that covers the colonies. As the cyanobacteria continue to grow up through the sediment, a new layer forms. This process occurs over and over again, creating layered mounds, columns, or sheets.
Fossils of different species of stromatolites can be found in different areas of the park. Stromatolites that lived in the Precambrian played a major role in increasing the amount of oxygen in the atmosphere of the primeval Earth ("The Great Oxygenation Event"). Living stromatolites can be found today at Shark Bay in western Australia.
Check out my Montana Hiking Blog - lots of geology!
Source: T.N. & E.L. Taylor. 1993. The Biology and Evolution of Fossil Plants. Prentice Hall, New Jersey.
The photo was taken below the crater on the north slope of the volcano. Loowit Creek originates from melting snow and ice in the crater. Much of the water comes from Crater Glacier, which has formed and grown around the lava domes over the past several decades. Loowit Creek has cut down through the volcano, exposing the alternating layers that give composite volcanoes their name. Also known as stratovolcanoes, volcanoes like St. Helens consist of alternating layers of explosively erupted pyroclastics (ash, cinders, etc.) and lava flows.
Above: Drone photo of my daughter and I on top Ear Mountain
The front of what?Ear Mountain stands along the boundary between the mountains and the prairie 70 miles northwest of Great Falls (map); an area Montanans refer to as “The Front”. The name probably originates from the view enjoyed by those approaching from the east - That of a long wall marking the abrupt end of the great plains and the beginning of (front of) the mountains. The area, which extends northward to Glacier Park and beyond is known for its scenic beauty, grizzly bears, Chinook winds, and fascinating geology.
Sea creatures in Montana?
Ear Mountain along with many of its neighboring ridges, peaks, and cliffs consist of the Madison formation; layers of limestone and other carbonates, ranging from 275-520 meters thick, and made of sediment laid down 330-340 mya when much of the western USA was the floor of a shallow, tropical ocean (map). The Madison forms many of the state’s most iconic landforms, including the Gates of the Mountains, Mission Canyon, the Lewis and Clark Caverns, and the Bighorn Canyon. The Grand Canyon’s “Redwall limestone” and the limestone that surrounds the Black Hills of South Dakota are equivalent strata. In places the Madison is especially fossiliferous. Those adventurous enough to climb Ear Mountain will be treated to an abundance of horn coral, as they walk the perimeter of the plateau.
Not your ordinary faults.
Perhaps the most fascinating aspect the Ear Mountain and the surrounding region is the way the Madison formation and other layers were deformed as these mountains were built. In response to the collision of the Pacific Plate and the North American Plate 115-50 mya, immense slabs of rock broke, and then slid up and over younger layers to their west. Mountains formed by this over-thrust faulting extend from Helena northward through Glacier Park into Alberta (called the Lewis Thrust Belt). Although this provided some of the most scenic mountains in the state, the orientation of the slabs in the 60-mile stretch between Augusta and Heart Butte (map) is especially unique. In this area thinner slabs of rock slid eastward over younger rock layers like shingles on a roof to form distinct high ridges and deep valleys that run parallel to each other as shown in this photo.
Term: Mississippian Period
Related links:
More About the Thrust-Faulting Along "The Front"
One of the keys to understanding ocean currents, and the "ocean conveyor belt" is realizing how temperature and salinity affect the density of water - referred to as thermohaline circulation. As water gets colder and/or saltier, it tends to sink (density current). The lab-activity shown in the video is one of our favorites at Helena High School. We call it "The Briny Deep". Students start with 800 ml of room temperature water in the tilted box, then mix various types of water (salty, cold, hot), make predictions, and then pour.
Credit for the demo goes to WARD's Science. The activity shown in the video is part of a kit that we purchased from WARD's, called "Exploring Convection". The kit also includes a second lab-activity that helps students understand the role convection plays in causing wind. Both labs come with great handouts that guide students through the activities and then follow up with questions that help them understand real-world applications.
