Finding Glacial Lake Agassiz with Google Earth

About 8200 years before present Glacial lake Agassiz was the largest lake in the world. It covered over 840’000 km2 in Canada (Manitoba, Saskatchewan, Ontario) and the US (North and South Dakota and Minnesota).

In this time of Climate warming it is particularly interesting to study some of the past changes in climate. Google Earth provides a unique tool to explore the maximum extent of this lake and its ultimate recession and drainage. This folder contains a series of land form features which can be used as reference and "legend" for mapping - exploring the maximum extent of this unique glacial lake.

The map below was completed in 1895 by Tubman (USGS) one of those remarkable early explorers. The map is already quite amazing if you take into consideration the limited access and the tools available. Just imagine what he could have done with GE.

Just imagine that you are in his shoes and you have suddenly access to Google Earth. How would you have improved this map? Surely you can do better with GE!

Lake Agassiz Interpretation and Exploration legend-Guide

  
   
This map was prepared by Warren Tupham who wrote a very interesting monograph published by the US Geological Survey in 1986. Of course many publications since that time have improved upon this map. The question is: Can you do better in establishing the maximum extent by using Google Earth???
Add your placemarks for former beachlines and try to find other signs of the maximum extent of the lake and retreat of the massive ice sheet.
The place marks in the Google Earth folder provide examples of interpretation of some of the glacial lake features which can be used as a "mapping and exploration legend"
   
Glacial lake Beachlines  
Glacial Lake Agassiz receded from the top of the Duck Mountains Plateau (a ground moraine) on the left to the present day Lake Winnipegosis on the right. Numerous beach lines can be seen showing the many stages of this retreat. Many of the early roads were constructed on the former beaches.

With Google Earth you can follow these beach lines along the southern and western shorelines former shorelines of lake Agassiz. The northern and western shorelines are a bit more complex to map.
Undraped DEM, 8.0x VE, Orthogonal View of the Beach lines in the satellite image above. The Upper and Lower Campbell beaches are shown. Source: Manitoba Geological Survey
   
 

Glacial lake bottom ice scour features in the Red River valley
The Red River Valleyforms the glacial lake bottom with heavy clay deposits. The scars in the landscape are thought to be the result of floating ice bergs and ice flows scouring in the soft glacial lake bottom.Here they are enhanced by the light snowfall in the right side of the image. These features occur in many parts of the former lake bottom, on agricultural and forested areas.
   
Assiniboine River Glacial Lake Delta  

A large delta was formed when the then much larger Assiniboine River drained into the glacial lake. Extensive sandy deposits can be seen on the west side as moving (A) or stabilized sand dunes (B) and bare range land . D shows the former lake bottom with clay deposits and C&E indicates former beach lines.

The land capability for this area obviously reflect these different parent materials [+]
   
Interlake Drumlinized Plain with Ice Scour Features  
This area shows the intersecting lineaments, thought to be the scars of ice bergs and ice flows in Glacial Lake Agassiz, super imposed of a extensive plain showing clear signs of glaciation. The darker forest covered, parallel ridges in the top of the image, are drumlins, shaped by the flow of the massive ice sheet and showing the direction of the flow.
   
End Moraine with a Series of Glacial Lake Beachlines  

The Pas Moraine shows a stagnant stage in the retreat of the large ice sheet. The fluted stripes in the landscape (E) show the direction of the ice flow. The dark ridge in the middle is the end of the ice sheet where glacial tills and end moraine formed a significant elevation in the landscape. About 10 different former glacial beach lines can be seen (B). The are essentially wave washed sand and gravel beaches. Typically roads follow beach lines, as road construction is easier and sources of gravel are close by.

The CLI mapsheet description provides more information on the ecology of this area [+].
   
Lake Modified Esker- Kame Complexes  
This is an example of the delta of an esker kame complex formed by a major "river" under the ice sheet. The wave washed beach lines can clearly be seen on this dominant landscape feature formed from gravel and sand with a forest cover of Jack Pine. Even in the surrounding peatlands parallel beach lines can be seen where Black Spruce cover is denser. In these areas a thin layer of lacustrine clays can be found on top of the sand. With GE you can follow the esker in a north eastern direction. This delta coincides with another end moraine stage of the retreat of the ice sheet. In this area the crest of the end moraine is hidden under clay and organic deposits, but drainage pattern in the extensive wetlands here show its highest points. Permafrost occurs in peatplateaus and palsas in these wetlands [+].
   
Northern Extent of Lacustrine Clays as shown by Shoreline Erosion of Southern Indian Lake  

  		Are we approaching the northern extent of Glacial Lake Agassiz? South Indian Lake shows an interesting change in water color. The southern part is covered by lacustrine clays, deposited in a glacial lake. The clay shorelines are eroding and create a high sediment load in the southern and middle portion of the lake. This effect has been increased by the higher water level caused by the hydro-electric developments in this area. The impact of erosion is increased , because permafrost in clay is quite common here. In the Northern part the water is dark, and clay is absent.
   
Glacial Lake Beaches and the Red River Plain  

The east side of the Red River Plain is marked by a series of beach lines. Part of the eastern shoreline? it is clear that the area to the right formed at one time an island, since the beachlines can be traced around it. Of course beach lines can be found as far south as Fargo. Try to find them.
   
   

Google Images= "Issue Atlas"

  

If you need some more clues to interpret the maximum extent of the lake there is of course always Google to help you find relevant information. One of the most effective and direct search approaches for environmental issues is Google Images. It is almost as if Google Images presents you with a real time issue atlas of "maps " which you can overlay on Google Earth.

As example for this exploration game I used "lake Agassiz" for an image search and I took the following screen shot of the search. This is the first page. It is amazing that all except one are maps rather than photos or other illustrations. They all lead information and web sites pertinent to this quest.
 
Since the work of Warren Upham many researchers have studied and debated the extent and evolution of Glacial Lake Agassiz.. A good overview of this work is presented by Thorleifson of the Geological Survey of Canada in his : Review of Lake Agassiz History. This review includes a series of maps depicting the various stages of the Lake.
 
 
Massive Flood Event 8200 years Before Present caused abrubt climate change
This image give a good visualization of the Lake Agassiz situation, dammed by the waning Laurentide Ice Sheet. The final drainage of this lake produced a flood that released 150,000 km3 northward to Hudson Bay. Ultimately the freshwater released from the flood was routed to the Atlantic Ocean. The ocean response to this huge influx of freshwater is thought to be the trigger for the cold event that occcurred around 8,200 years ago.
Authors:
Clarke, G. K. C., D.W. Leverington, J. T. Teller, and A. S. Dyke. 2004. Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8,200 BP cold event. Quaternary Science Reviews, 23, 389-407.		 link to source:EOS @UBC
 

A NASA Goddard Institute for Space Studies (GISS) computer model simulated the 8,200-year climate response to freshwater entering the Hudson Bay. The left and right panels show simulated changes in surface air temperature and precipitation, respectively (Image credit: NASA GISS). The model confirms and visualizes the impact of massive flood of fresh water into the North Atlantic and displays the abrubt change.
 

Lake Agassiz outburst sparked 'Big Freeze' in Europe 12,800 years ago

information source: Bill Patterson in the New Scientist ; Ottawa Citizen Story
Lake Agassiz outburst sparked 'Big Freeze' in Europe 12,800 years ago. When an ice wall collapsed somewhere along Lake Agassiz's northeastern rim about 12,800 years ago, its freshwater contents gushed rapidly into the North Atlantic, wreaking havoc with ocean circulation patterns and plunging Europe into an unprecedented and prolonged winter that lasted centuries. In a study that highlights just how quickly a mini ice age took hold of Europe after the dramatic collapse of a glacial ice dam in ancient Canada, Saskatoon scientist Bill Patterson has gathered evidence suggesting the "Big Freeze" - a sudden and severe global cooling known to experts as the Younger Dryas - happened within three months of the Canadian cataclysm. But rather than unfolding over a decade as widely believed, the extreme chill set in so swiftly that ecosystems in the northern hemisphere were radically transformed within a single season, a research project led by Patterson has discovered. "If (Canada's earliest aboriginals) lived near Agassiz, they may simply have seen the lake level drop as the lake shrunk in size," Patterson said. "If they were in the East near the outlet, they would have seen what would look like a large, fast flowing river."
Lake Agassiz outburst sparked 'Big Freeze' in Europe 12,800 years ago. When an ice wall collapsed somewhere along Lake Agassiz's northeastern rim about 12,800 years ago, its freshwater contents gushed rapidly into the North Atlantic, wreaking havoc with ocean circulation patterns and plunging Europe into an unprecedented and prolonged winter that lasted centuries. In a study that highlights just how quickly a mini ice age took hold of Europe after the dramatic collapse of a glacial ice dam in ancient Canada, Saskatoon scientist Bill Patterson has gathered evidence suggesting the "Big Freeze" - a sudden and severe global cooling known to experts as the Younger Dryas - happened within three months of the Canadian cataclysm. But rather than unfolding over a decade as widely believed, the extreme chill set in so swiftly that ecosystems in the northern hemisphere were radically transformed within a single season, a research project led by Patterson has discovered. "If (Canada's earliest aboriginals) lived near Agassiz, they may simply have seen the lake level drop as the lake shrunk in size," Patterson said. "If they were in the East near the outlet, they would have seen what would look like a large, fast flowing river."