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In order to count this Earthcache as a find, you must complete the following tasks and email the answers to me.
1. What is the elevation?
2. Where was the original Red River channel located? When was the Red River rerouted?
3. Trace the flow of the Red River from its origin at Lake Traverse to its draining point into Lake Winnipeg.
4. Describe how the elevation drops from the Red River’s source to Lake Winnipeg. How many inches per mile is this?
This Earthcache is located at the Veterans Memorial bridge that spans the Red River and separates Fargo from Moorhead and North Dakota from Minnesota. Please park on the Moorhead side along 4th Street and take the pedestrian walk to the site. Enjoy!
The Wisconsin glaciation occurred somewhere between 30,000 and 10,000 years ago. During this last ice age, the northern part of North America was covered by a glacier. As the ice sheet started to break apart and melt, it sent strong and fast-moving streams of water southward. This water dammed up behind a barrier of glacial debris known as the Big Stone Moraine and pooled into a lake larger than all the Great Lakes combined.
About 13,000 years ago, this gigantic lake, once known as Lake Agassiz, covered present-day Manitoba, western Ontario, eastern Saskatchewan, northern Minnesota, and eastern North Dakota. At its greatest extent, the lake covered up to 440,000 square kilometers--roughly the size of Uzbekistan or Iraq. Lake Agassiz was much larger than any current lake in the world, including the Caspian Sea, and held more water than contained by all lakes in the world today. At its maximum, Lake Agassiz was over 300 feet deep--where downtown Fargo and Moorhead sit today.
The lake drained at various times and in all directions. It drained south through the Traverse Gap into the Glacial River Warren, east through present-day Lake Nipigon (then Lake Kelvin) to present-day Lake Superior, and west through the Mackenzie River through the Yukon Territory and Alaska. It is believed that around 13,000 BP there was a major flood of the Lake, causing it to drain through the Great Lakes and St. Lawrence River into the Atlantic Ocean.
Climatologists believe this flood and draining may have been the cause of the Younger Dryas stadial. The Younger Dryas stadial, also known as the Big Freeze, was a geologically brief period of time (about 1300 years) in which the climate returned to ice age conditions. The return of ice for sometime offered a bit of a reprieve for the Lake. About 9900 years ago, after the ice sheet retreated north of the Canadian border and slowly melted, Lake Agassiz refilled. These events of Lake Agassiz had a significant impact on climate, sea level, and possible early human civilization.
The majority of the final drainage of Lake Agassiz occurred within a very short amount of time--about a year. A recent study by Turney and Brown links this rapid drainage (and subsequent global seal level rise of about one meter) to the expansion of agriculture in Europe. This study also suggests that this drainage and previous flooding may also account for various flood myths of prehistoric cultures, including the Biblical flood.
The last major shift in the drainage of Lake Agassiz took place about 8400 years before present. During this time, the lake took up its current watershed and slowly drained into the Hudson Bay. Over the next 1000 years, the Lake drained completely.
Lake Winnipeg, Lake Winnipegosis, Lake Manitoba, and Lake of the Woods are relics of the ancient Lake Agassiz. Other geological and geomorphological evidence for Lake Agassiz can also be seen today. Raised beaches, many miles from any water, mark the former boundaries of the lake at various times. Several modern river valleys, including those of the Assiniboine River and the Minnesota River, were originally cut by water entering or leaving the lake. The fertile soils of the Red River Valley, which are some of the richest in the world, are formed from deposits of silt from Lake Agassiz. Fargo-Moorhead currently sits on 105 feet of sediments deposited by Lake Agassiz.
The Red River started to form about 9000 years ago in the Fargo-Moorhead area as Lake Agassiz drained northward. The Red River flows across the flat lakebed of Lake Agassiz. The Red River Valley, which is one of the flattest landscapes on Earth, is situated on this ancient lakebed. From its origin near Breckenridge, Minnesota to the international border near Emerson, Manitoba, the Red River Valley slopes only about one foot per mile. The river, which flows slowly and is small most of the time, does not have the energy to cut a deep gorge. Instead, it curves and beds across the low-lying lands as it moves north.
NOT A LOGGING REQUIREMENT: Feel free to post pictures of your group at the area or the area itself - I love looking at the pictures.
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