As noted before, Yellowstone Park lies over a thermal plume or pipeline of lava extending from the Earth’s core.
Volcanic forces generated by the plume caused three monstrous eruptions that caused a 40-mile long chain of mountains to collapse into a bowl-like shape called a caldera. Lava flows within the calderas built hills, canyons, lakes and other natural features that made the park both unique and beautiful. But, Mother Nature wasn’t finished with the park yet.
Vast glaciers have covered Yellowstone Park twice in the last 200,000 years. First, Bull Lake and, most recently, the Pinedale glacial period.
In fact, all this talk about global warming, ozone and fossil fuels could possibly be just so much bunk. Every 100,000 years for the last 700,000 years, there has been a glacial period. In between glacial times temperatures rise, causing tropical temperatures in the Earth’s temperate zones. Answers to why this occurs are elusive, but might be due to variations in the Earth’s orbit around the sun.
Consider that for 90% of the last 600 million years world temperatures averaged 72 degrees Fahrenheit. Today they average 58 degrees, and during glacial periods they averaged 50. It is safe to say the Earth is in a cool period of its history. See how easy it can be to possibly mislead lawmakers who know nothing of geology or the Earth’s climatic history by simply saying temperatures are rising? That what man does is largely irrelevant?
So, never stop educating yourself dear reader; we need all the facts to make correct decisions.
But back to Yellowstone and the latest glacier, where around 80,000 years ago the weather gradually cooled and worsened. Heavy snowfalls in the mountains surrounding the park built up thick ice fields in their extensive uplands. Gradually, the hundreds of growing glaciers began creeping down the valleys, eventually congregating at the lake. Over the years as they grew ever larger and higher they helped to generate their own climatic conditions which encouraged more and more snow to fall on them.
Over time, a vast ice sheet gradually formed, blanketing the area in a frozen grip. The ice continued to grow thicker and higher until eventually the area above Yellowstone Lake, the lowest point of elevation, became the highest point of the vast glacier, the ice growing over 4,000 feet thick. Exactly what happened to cause this most unusual phenomenon is unknown. I would guess that somehow natural forces funneled large ocean weather systems laden with moisture to the lake. Endless storms converged there, burying the lake area in massive snowfalls for centuries on end.
The Pinedale Glacier reached its maximum size about 25,000 years ago. This great ice sheet covered not only the park; it stretched from Chico Hot Springs, Montana, to the Snake River Overlook at Jackson Lake, Wyoming, just above the city of Jackson Hole, a distance of 120 miles. Not bad sized, a little more than the distance from Bradford to Rochester as the crow flies.
As you can imagine, ice that thick and heavy has tremendous power. Over thousands of years, the relentless mass of ice moved irresistibly forward, digging deep into the rock, scouring out valley floors, grinding and gouging everything before it. As the glacier’s hard, sharp ice, driven by tons of weight, sculptured the entire face of the landscape, immense quantities of soil, sand, gravel, rocks and large boulders were incorporated into it. Like a giant plow the glacier’s face pushed heaps of debris before it as it ground slowly forward. These mounds are called terminal moraines.
As the Pinedale Glacier pushed ever southward, it eventually reached the Grand Teton Mountain range, merging with the glaciers pushing down the steep valleys of the Tetons. Together they dug Jackson Lake, a glacial scour basin over 800 feet deep. Today Jackson Lake’s waters reach 425 feet in depth, with over 400 feet of glacier sediment beneath them burying the hard, rock floor at its bottom.
During the brief glacial summers, warmer temperatures melted surface ice and snow, creating many muddy streams flowing out of and off the glacier. These many streambeds wandered aimlessly in front of the ice mass and deposited their sediments. When fall came the lower temperatures stopped the thaw and dried up the streams. Violent autumn winds then picked up sediments from the dry streambeds and blew them away in great clouds of dust. When this dust dropped back to the earth it was called loess. There are loess deposits on high terraces south of Jackson over 20 feet thick.
When the glacier began shrinking backwards approximately 15,000 years ago, they continued to reshape the land beneath them in countless ways. Water cascading off the ice sheet dug new river beds and streams. The millions of tons of soil, sand, rock and boulders the retreating glacier had trapped in its ice formed additional moraines or low hills while waterfalls as high as skyscrapers dumped their sediments in piles for years throughout the Yellowstone area. Very large lakes were created in lower areas within the glacier’s vast ice field. They would grow larger and larger, then suddenly burst through their ever-thinning walls, the torrents of sediment filled floodwaters forming large outwash plains. The city of West Yellowstone stands on such a flat, level outwash plain.
As the glacier retreated, the debris that had collected within them surrounded isolated, surviving blocks of ice. When these landlocked icebergs, so to speak, finally melted, the holes they left became ponds, kettles and small lakes. The list goes on and on. Suffice it to say that the great variety of size, shape and form you see in the park today is the result of millions of years of work by flood, fire, massive explosion, lava, glacial activity, wind, steam and earthquake. Who can say they even remotely comprehend the diversity and immensity of the powers that created it?
If you ever get the opportunity, you simply have to visit Yellowstone Park. It will take a week to see everything there, hike, visit all the sights, relax, maybe do some fishing and, of course, take many pictures. It will be a week of awe-inspiring sights you’ll never forget.