chapter 11 origin and ages of lakes glacial tectonic volcanic riverine coastal solution reservoir
TRANSCRIPT
Chapter 11Origin and Ages of Lakes
• Glacial• Tectonic• Volcanic• Riverine• Coastal• Solution• Reservoir
Glacial lakes
• Developed by an ice barrier– proglacial lakes)
• Developed by glacial erosion– Cirque and paternoster lakes,
fjords, and kettle or pothole lakes• Developed by glacial deposition
(moraines)• Developed by a mixture of
glacial activity
Kettle lakes (ex Dundee WI) formed when block of trapped glacial ice in accumulated till melted.
Plunge-pool lakes formed at the base of a waterfalls off retreating glaciers. melt water
Space-shuttle photograph of the Finger Lake district in western New York.http://www.geospectra.net/kite/ny_finger/finger.htm
Morainal damming formed the Finger Lakes, Lake Mendota (& many WI lakes)
Lake Baikal• Max depth 1,620 m• Length: 636 km• Width: 80 km• Shoreline length: 2,100 km• Volume: 23,600 km3 (almost 20% of the world’s surface fresh water, more than all five Great Lakes combined)
Tectonic Lakes (formed by deep earth crustal movements)
Rifting A geologic term that describes the process that occurs when land sinks between two parallel faults.
Lake Chad, which once straddled the borders of Chad, Niger, Nigeria and Cameroon, has shrunk by an estimated 95% since the mid 1960s, due to the growth of agriculture and declining rainfall. Image: Unep
Riverine lakes (book Fig 11.17): Dominant lake type at low latitudesOxbow, blocked-valley, floodplain lakes (varzea)
River meander becomes separated Oxbow lakes (billabong)
http://www.lmic.state.mn.us/gifs/wilkin_oxbow.jpg