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Saturday, January 28, 2017

Hiking into the Crater of Mt. St. Helens

This photo was taken during a hike that I did a few years ago into the crater of Mt. St. Helens. The landscape was rocky and gray with hardly any vegetation - but VERY interesting. Plus, we were treated to an "up close and personal look" at geology in action - glaciation, volcanism, and a canyon being carved by melt-water from Crater Glacier. As an Earth Science teacher, I felt like a kid in a candy store. For more about this trip (many downloadable photos), CLICK HERE.

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.

Thursday, January 19, 2017

Fascinating Geology of Ear Mountain in Montana

Photo courtesy of Sam Beebe, www.ecotrust.org

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.

Related links:

Hiking on Top of Ear Mountain

More About the Thrust-Faulting Along "The Front"

More About the Madison Limestone

More About the Sevier Orogeny

The Madison Limestone in Montana

Thursday, January 12, 2017

Understanding Thermohaline Circulation

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.

More About Thermohaline Circulation from Wikipedia

Article About Possible Shut-Down of the Ocean Conveyor Belt

Saturday, January 7, 2017

Time to start hyping the eclipse of 2017!

This 48-second NASA video provides a view of the United States during the total solar eclipse of Aug. 21, 2017, showing the umbra (black oval), penumbra (concentric shaded ovals) and path of totality (red). This version includes images of the sun, showing its appearance in a number of locations, each oriented to the local horizon. Credit: Ernie Wright, NASA Visualization Studio

Other Eclipse Resources
1. Watch this 2.5 minute video to see how he created the animation shown in the video above.

2. Below is another 48-second video from Ernie, showing what the eclipse will look like from the Moon.

Thanks to Rick Dees (Huntley-Project High School) for showing me these resources!

Interested in hiking? Check out my Montana hiking blog at bigskywalker.com.