Glaciation In The Pacific Cordillera Of North America

Earth has experienced many episodes of dramatic climate changes with different periods in earth history. There have been periods during which the entire planet has been covered in ice and at another time it has been scorchingly hot and dry. In this regards, earth has experienced at least three major periods of long- term frigid climate and ice ages interspersed with periods of warm climate. The last glacial period which current glaciers are the result of it, occurring during the last years of Pleistocene, from approximately 110,000 to 10,000 years age (Clayton, 1997). Indeed, glaciers present sensitive indicators of climate change and global warming and by estimating and monitoring the dynamic evolution of these ice masses, several

Much of Michigan’s landforms can be traced to the Pleistocene period, which lasted until around 10,000 years ago. Of the four periods of glacial movements in the Pleistocene period, the Nebraskan, Kansan, Illinoian and Wisconsin, the Wisconsin Glaciation is the most prominent cause of the current Michigan landscape in the Upper Peninsula and Lower Peninsula (Damery, 2001). The Wisconsin Glaciation occurred about 100,000 years ago. The climate cooled, and the Laurentide Ice Sheet was spread across the continent. About 31,500 years ago, this glacier began to approach Wisconsin. The Laurentide Ice Sheet expanded in the area that today is Wisconsin and Michigan, for 13,500 years before the ice began to melt and retreat. As this ice sheet moved south, valleys were filled in, the drainage systems of rivers were blocked, and major basins that are now the Great Lakes were gouged. The graphic below shows the land that the Laurentide glacier

The present configuration of the Great Lakes basin is the result of the movement of massive glaciers through the mid-continent, a process that began about one million years ago. . . . Studies in the Lake Superior region indicate that a river system and valleys formed by water erosion existed before the Ice Age. The Glaciers undoubtedly scoured these valleys, widening and deepening the and radically changing the drainage of the area (Encyclopedia Britannica )

The glaciation is very confusing to those who don't know about glaciers so here is some background information. The last glacial advance started about 75,000 years ago and the last

Ice ages are well documented in Earth’s history, and they are proven to be relatively frequent. But what if that ice age persisted over not just regions near the poles, but around the equator as well? The term “snowball Earth” refers to a condition where Earth is completely covered by ice. Evidence indicates that snowball Earth may have been around in the Neoproterozoic. In fact, evidence points to the conclusion that these conditions happened three separate times in the Neoproterozoic. A snowball Earth condition is hard to prove, but this theory may explain several different phenomena. However, it is not accepted by all, there is evidence against a snowball Earth as well. Some believe that a snowball Earth would not have been possible in past climate conditions while there are views that defend the idea of more of a ‘slushball’ Earth rather than a planet entirely frozen on the surface.

First, sediment samples and animal remains from the Bering Sea prove that the Beringia was habitable at the height of the ice age or 21,000 years ago. According to Elias: “humans did not survive the last ice age’s peak in northeastern Siberia, and yet there is no evidence they had reached Alaska or the rest of the New World either” (Elias). At this point, Elias’s theorizes that people lived on the Beringia, a 600 mile wide area between Siberia, Russia, and Alaska. Furthermore, “sediment cores” (Elias), from the Bering sea indicate that the

Global warming is the warmth of Earth’s temperature by the sunlight as a main cause. 30 percent of the sunlight reflected back into space by clouds, and the remaining 70 percent is absorbed by land, air and ocean. Solar energy does not stay bound up on Earth’s environment perpetually. Global warming is a phenomenon, it has started from the last century. It impacts on Earth and that can lead to climate change in the world. A lot of scientists have approved that global warming is a fact and have approved natural changes and they discovered the reason behind that is global warming. “Understanding the cause of the Pleistocene ice ages has been a significant question in climate dynamics since they were discovered in the mid-nineteenth century. The identification of orbital frequencies in the marine record, a proxy for global ice volume, in the 1970s demonstrated that glacial cycle are ultimately paced by astronomical forcing” (Jeremy. D. 1). Therefore, we should save our planet by preventing global warming from happening.

During the Pinedale glaciation, there were two ice sheets. One of them being the Cordilleran Ice Sheet. The Cordilleran Ice Sheet was comprised of three main lobes. The Puget Lobe, Okanogan Lobe, and the Purcell Trench Lobe. The one lobe in Northern Idaho, near present day Lake Pend Oreille, was the Purcell Trench Lobe. When these sheets of glacial ice moved south they caused an ice dam to occur. J.T. Pardee states that “The evidence of icebergs, together with the apparent regency of the lake and the variable height of its surface, connect this lake with the glacial period, and readily lend themselves to the suggestion that its dam was of ice” (Pardee, 1910) This ice dam blocked the Clark Fork River which is near the boundary of Idaho and Montana. The water from the river was blocked and began to build up and formed Glacial Lake Missoula. Water

As this river of ice moved slowly over the hidden rocks, the base of the glacier grazed millions of sediments in the Earth. The after math composed of soil, pebbles, cobbles and boulders that pushed forward, smashing rocks into glacial dust. Then the climate began to warm. Melted water from the glaciers carried the soils and rocks away from the dissolving glacier, depositing its leftovers throughout the landscape. This combination of soils and rocks deposited. Then low hills, or moraines, were created across the state. Michigan's glacial drift averages 200 to 300 feet. The scraping of boulders created particles. The heaviest pieces formed ridges, which made the stream's flow in a certain direction. Lighter materials were carried further, dropping on the way as the flowing water slowed. These materials dried forming enormous, flat colored areas of sand, silt, clay creating a mixture called the outwash plains. The weight of the glacier over the Michigan basin was dropping, and the Earth began to recoil, like a sponge coming back to its original shape. The Michigan landscape began to appear. Plants began to approach on the shriveled landscape. Individual plants found a suitable growing environment near each other, which created a suitable home for

Michigan’s landscape over the past millions of years was formed from glaciers. During the last Ice Age, which was approximately two million years ago during the Pleistocene Epoch, glaciers covered some of Michigan and went through cycles of advancing in a southern direction (towards The Midwest of The United States) and recession back towards Canada. These cycles of alternating temperature led to the formation of

Many millions of years ago the Sierra Nevada was filled with ocean water until sediments began collecting and formed mountain ranges. Over a large period of time, the mountains began to wear out and became immersed in the ocean once again. Many different particles and materials began to make layers and created the first mountain system. After the Jurassic era, “…new strata were folded and crumpled and invaded by molten granite from below” (Beatty, 1943). A large

A glacier occurs when the climate of an area is so cold that new snow does not completely melt each summer and more snow is added in the winter. After many winters the accumulation of this snow becomes compact and re-crystallizes, thus forming a glacier. Currently, glaciers cover about ten percent of the Earth's surface. Yet, in the past, glaciers covered much more land and were thousands of meters thick. (Tierney)

Glaciation that are widespread can be identified based on the subglacial tillite, which is a thick layer of sediments that settle down beneath glaciers or ice caps. On top of this subglacial tillite layer is deposited marine carbonate, also known as cap carbonate. Based on their paleolatitude designated by glacial sediments’ paleomagnetism, it can be determined that these deposits are from equator region. The interaction between two types of sediments, marine (like carbonate) and subgacially deposited sediments, indicate that the glaciers had approached marine coastlines.

Ice is one of the first indicators of global warming actually occuring and it is important for research to be done on these layers of before they disappear. The recession of glaciers and the fragmentation of ice caps has been a clear sign to many that rising temperatures are having an impact, even on our very lives.

Climate change is defined as “a change in global or regional climate patterns, in particular a change apparent from the mid to late 20th century onwards and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.” Climate change has happened as a cycle throughout history, with ice ages occurring, and then warming. The earth naturally warms and cools, but due to the burning of fossil fuels the rate is growing exponentially.