Itasca NW

Nathan Asplund

Basic Information • Itasca County, with a population of approximately

43,000, is located in north central Minnesota. • The county is the third largest in the state,

approximately 3,000 square miles. • There are 16 cities and 42 organized townships. • We have 1,000 lakes and over 1,000 miles of

snowmobile and skiing trails. • Itasca County offers great outdoor recreational

opportunities, including skiing, camping, hiking, boating, hunting and fishing.

http://www.co.itasca.mn.us/

Climate and Temp • A climate is made up from the major air masses

from western United States, Canada and the Mississippi River valley results in seasonal weather with major extremes in Itasca County.

• Air masses moving north from the Mississippi River valley bring a large portion of the precipitation and humidity.

Rivers

Meandering river

Oxbow lake

Rivers cont.

A meander is formed when the moving water in a river erodes the outer banks and widens its valley

A U-shaped body of water formed when a wide meander from the main stream of a river is cut off to create a lake

How the landscapes were formedThe Wadena Lobe advanced from the north several times. Its last advance deposited the Alexandria moraine (which was later reglaciated), the Itasca moraine, and the drumlin fields spanning Otter Tail, Wadena, and Todd counties. The Rainy and Superior Lobes came out of the northeast and advanced, sometimes with and sometimes independently of the Wadena. Its last advance left a coarse-textured till of basalts, gabbro, granite, iron formation, red sandstone, slate, and greenstone strewn across the northeastern half of Minnesota and as far south as the Twin Cities. The Des Moines Lobe originated in the northwest and advanced in a southeasterly direction across Minnesota and into Iowa. Its fine-textured till consisted of limestone, shale, and granite fragments, from which developed the fine prairie (now agricultural) soils found in these areas.

Information from http://www.dnr.state.mn.us/snas/naturalhistory.html

Basic Geography of Itasca• Beach ridges• Melt water channel• Esker or esker-like ridge• Drumlin• Tunnel valley• Ice-walled lake plain• Fan

Beach ridgesA beach ridge by Little Winnibigoshish lakeIn Itasca county

Example of a beach ridge

Melt Water Channel

Drainage channel cut by melt water possibly by glaciers

Eskers

Sinuous ridge of interbedded sand, gravel,and silt; interpreted to have been deposited in an ice-walledchannel or tunnel of a glacial melt water stream. Deposited bymelt water of both the Koochiching and Rainy lobes, but drainagewas generally to the south and east within the lobes.

DrumlinOval or elongated hill believed to have been formed by the streamlined movement of glacial ice sheets across rock debris, or till

Tunnel Valley

Ice-walled lake plain

Ice-walled-lake plains form in the stagnant marginal zone of glacial Ice Sheets

Alluvial Fan

POSTGLACIAL DEPOSITS• Eolian sand• Beach sediment• Alluvium• Peat• Terrace sediment

Eolian SandEolian sand—Fine-grained sand more than 5 feet (1.5 meters)thick that forms low-lying barchans dunes and sheet-sand depositsthat display shallow depressions or blowouts. Interpreted to bewindblown sand.

Beach SedimentBeach sediment—Sand and gravelly sand in low-rising terracesalong the shores of Lake Winnibigoshish and other modern lakes.Interpreted as modern beach sediment; unit may include some ice pushsediment from windblown lake ice.

AlluviumAlluvium—Interbedded fine-grained sand, fine-grained sandy loam,and silt loam; shells, wood, and other organic debris are typicallypresent. Interpreted as the deposits of modern rivers during high-waterstages.

Peat

Peat—Organic material in various stages of decomposition; somedeposits include small bodies of open water. Interpreted asswamp deposits and deposits of freshwater lakes that have filledwith vegetation.

Terrance SedimentTerrace sediment—Sand and gravelly sand above the modernfloodplain of the Big Fork River but located lower than theglacial-lake plain. Interpreted as representing the former level ofthe floodplain of the Big Fork River. The river has incised moredeeply as the local base level has dropped over time.

Giants Range Batholiths

Anticline and Syncline

Faulting

Mylonite Zone

Found exact locations by drilling

Anticline and Syncline Cont.

Dikes and Sills

Inclined Fault

Overturned Fault

Example

Folds

Examples of folds

Works Cited• http://www.dnr.state.mn.us/snas/naturalhistory.html• http://www.co.itasca.mn.us/• Google images• http://reflections.mndigital.org/cdm4/item_viewer.php?

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