Glacial Evidence

U-shaped canyons, moraines and outwash plains are all visible in this photograph from the Snake River Overlook in Grand Teton National Park if you know what to look for.

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About 12,000 years ago, things on the North American Continent came to a grinding halt. The Ice Age was ending and the glaciers associated with the huge sheet of ice began to recede back up hill faster than they moved downslope. Glacial artistry, the changes made to the landscape, was about to be unveiled and is nowhere more evident than in Grand Teton National Park.

Like a sculptor’s chisel, glaciers created many of our landscapes today. For instance, if you see a canyon that is “U” shaped rather than “V” shaped, you know it was formed by a glacier. Cascade Canyon at Jenny Lake is a perfect example of a U-shaped canyon.

As the glaciers (there were many) scoured their way downhill, they carved and re-shaped the ground in front of them using the boulders and rocks picked up to help with the process. The material plowed, carved and swept from the canyon walls built up under the glaciers and like a conveyor belt, was deposited at the foot of the glaciers a bit at a time. Although this happened slowly, the process was relentless and built large long mounds known as terminal and lateral moraines. The large lakes along the east flank of the Teton Range (Jackson, Leigh, Jenny, Taggart, Bradley and Phelps lakes) were all formed behind moraines.

At the very top of the glaciers, high-walled amphitheaters known as cirques formed. As the ice moved downhill, it often carved out a basin beneath the cirque walls. Holly, Solitude, Amphitheater and many other small lakes in the Teton Range were formed this way.

As these huge glaciers melted, the meltwater formed rivulets, then streams then torrents as they joined together. They carried rocks, pebbles and silt that the glaciers had ground up and deposited it, size-sorted in great aprons with the largest material dropping out first and the finest silt moving the furthest, on the flatter plains in front of the glacier. These outwash plains are plainly visible as terraces from the Snake River Overlook along Highway 89 and indicate that glaciation on a large scale happened more than once in the Teton Range.

When streams and rivers form within or under the glaciers they may run for miles in ice-lined tunnels. Like any other moving water, they create deposits of rocks, gravel and sediment, in this case usually long winding ridges that may be 30 yards high, called eskers. This is one feature that doesn’t seem to be present in the Teton Range, perhaps because these glaciers were relatively short.

Far out on the outwash plain southeast of Jackson Lake is a lumpy piece of land known as the potholes. When the glacier retreated, massive chunks of ice were left partially buried in the glacial outwash gravels. When they melted, they left behind deep depressions knowns as kettles or potholes which often filled with water or became wetlands. The Pothole Turnout south of Signal Mountain is a great place to see these.

If you see an occasional rock or boulder far out on the valley floor, it is a glacial erratic. The glacier carried them downhill and then deposited them randomly.

Finally, there are times when the glaciers scoured down to bedrock—an unstoppable force meeting an immovable object. The result was a polishing and scratching of the bedrock (called glacial striae) that you may see hiking in the canyons of the Park.

What I find fascinating about all this is that once you know what to look for, any glacial landscape is as readable as a book. That is cool.

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.