Fascinating Geology of Ear Mountain in Montana

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:

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

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

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.

Triple Divide Peak - Glacier National Park, MT

Like the vast majority of peaks in Glacier Park, Triple Divide is a horn that was beautifully sculpted by glaciers during recent ice ages. These pyramid-shaped peaks are formed as three or more glaciers erode the sides of a single mountain. But, what makes Triple Divide extraordinary is the role it plays in dividing three major watersheds. Runoff from its east side flows into the Gulf of Mexico, the west side flows into the Pacific, and the north into the Hudson Bay. Runoff is melted snow or other forms of precipitation that drain off the land.

You might think a mountain with so much responsibility would tower over the landscape – not so. In fact, Triple Divide is surrounded by taller peaks in every direction. This photo was taken from Norris Mountain, within feet of the Continental Divide (yellow line). “Divides” are simply higher areas (not always distinct ridges or peaks) that separate drainage basins (watersheds). Of course, the Continental Divide (aka “The Great Divide”) is the most famous of all divides. The ridge that runs from Triple Divide to Mt. James in the upper left is another divide – called the Laurentian Divide (red line). It separates the Gulf of Mexico and Hudson Bay watersheds. The faint trail that can be seen descending from the pass between Mt. James and Triple Divide leads down into the Hudson Bay watershed.

The hike to Triple Divide Peak starts at Cut Bank Campground and follows a nice trail to Triple Divide Pass (7.5 miles one-way). From there you must go off-trail to reach the summit. The trip out and back from the campground is a difficult 16 to 17-mile hike with 2,900 ft. of elevation gain. Feel free to download and use any of my photos (see link below).

Related Links
1. Climbing Triple Divide Peak - Includes a Photo Tour
2. Map of the Triple Divide Area - Zoom in or out once the page opens.

Seven days of weather in 13 seconds!

One of the nice things about teaching today compared to when I started in 1982 is the availability of real-time weather-related images and animations. Here's a cool resource provided by the Space Science and Engineering Center at the University of Wisconsin-Madison. It shows 7 days of infrared satellite imagery in a 13-second loop. It moves pretty fast, but you can pause it to point out mid-latitude cyclones, Chinook arches, etc. CLICK HERE to watch it. This page provides several other viewing options, including GOES-East or West, infrared, water vapor, or visible, full-disk or continental US.

Another fun way to show current weather in motion is the WW2010 site provided by the University of Illinois. Once the page open, click on one of the image options, then select animate, choose the number of frames (4-96 hours), and then select "play" or advance the animation one frame at a time.

'Tis the Week of the Solstice

The Sun stops (not really) . . .
This view of Earth helps depicts the Earth on the Winter Solstice (around December 21 each year). It shows why days are so short and nights so long this time of year. To fully understand the shortness of our days, here's a few things to keep in mind:

1. Earth orbits the Sun once every 365.25 days.

2. The Earth's axis is tilted 23.5 degrees*. If it weren't, there would be no seasons and every place in the world would have 12 hours of daylight and 12 hours of darkness every day of the year. A common misconception about the seasons is that they are caused by Earth being closer or farther from the Sun at different times of the year. THAT IS NOT CORRECT. In fact the Earth is about 3 million miles closer to the Sun in early January than it is in early July! The average distance from the Earth to the Sun is 93 million miles.

3. The Earth spins on its axis once every 24 hours. This axis runs through the Earth from the North Pole to South Pole.

4. Around December 21, Earth reaches the position on its orbital path where the Northern Hemisphere is tilted away from the Sun. Six months from now, Earth will be on the opposite side of the Sun and our hemisphere will be "leaning" toward the Sun.

Good news and bad news . . .
As shown on the image, on December 21, residents of Helena (star) could have observed sunrise at 8:09 AM. (The large yellow circle shows the path of Helena during the 24 hours it takes Earth to spin on its axis.) As Earth continued to spin, Helena moved into darkness (sunset) at 4:43 PM. So, on this, the "shortest day" of the year, Helena experienced only 7.5 hours of daylight followed by 16.5 hours of darkness. In comparison, Anchorage, Alaska (A) would have experienced about 6 hours of daylight (sunrise at 10:14 AM, sunset at 3:41 PM). The good news is that after December 21, the amount time that Montana gets to spend in the Sun increases by minutes per day. This trend will continue until the Summer Solstice in June.

NOTE: The term "solstice" means "Sun stops." This term is used for December 21 because this is the day that the Sun stops getting lower in the sky (also directly related to Earth's tilt and the position of Earth on its journey around the Sun). This day is also the first official day of winter. On the Summer Solstice (first day of summer), the Sun stops getting higher in the sky.

*The tilt of Earth's axis does change slightly over tens of thousands of years, but the change during the course of one year is insignificant. Term: equinox

A picture is worth a thousand words . . .

It is very important that students understand how water drains off the land to form streams and rivers that eventually (usually) flow to the ocean. Images like this will definitely help. CLICK HERE to see several other images and an impressive animation, created by Imgur user Fejetlenfej,a geographer and GIS analyst.

A map such as the one shown above can be very effective in helping explain the concept of watersheds (and divides). Click on the map to enlarge - and appreciate the detail. It might also serve as the focus of a "bell-ringer". For example, have students write out 3 quality questions about the map - stipulating that each question must begin with the word "why". Then in your discussion of the bell-ringer, ask if they would be able to use the map to mark the location of the Continental Divide (aka the Great Divide).