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This is located in a city park of Hastings, MN.
Central Minnesota is composed of (1) the drainage basin of the St. Croix River (2) the basin of the Mississippi River above its confluence with the Minnesota, (3) those parts of the Minnesota and Red River basins on the glacial uplands forming the divides of those two basins with that of the Mississippi, (4) the Owatonna Moraine atop a strip of land running from western Hennepin County south to the Iowa border, and (5) the upper valley of the St. Louis River and the valley of its principal tributary the Cloquet River which once drained to the Mississippi before they were captured by stream piracy and their waters were redirected through the lower St. Louis to Lake Superior. Glacial landforms are the common characteristics of this gerrymander-like region.
The bedrock ranges in age from Archean granites to Upper Mesozoic Cretaceous sediments, and underlying the eastern part of the region (and the southerly extension to Iowa) are the Late Precambrian Keweenawan volcanics of the Midcontinent Rift, overlaid by thousands of meters of sedimentary rocks.
At the surface, the entire region is "Moraine terrain", with the glacial landforms of moraines, drumlins, eskers, kames, outwash plains and till plains, all relics from recent glaciation. In the multitude of glacier-formed depressions are wetlands and many of the state's "10,000 lakes", which make the area prime vacation territory. The glacial deposits are a source of aggregate, and underneath the glacial till are high-quality granites which are quarried for buildings and monuments.
The subregion of East Central Minnesota is that part of Central Minnesota near the junction of three of the state's great rivers. Included are Dakota County, eastern Hennepin County, and the region north of the Mississippi but south of an east-west line from Saint Cloud to the St. Croix River on the Wisconsin border. It includes much of the Twin Cities metropolitan area. The region has the same types of glacial landforms as the remainder of Central Minnesota, but is distinguished by its bedrock valleys, both active and buried.
The valleys now hold three of Minnesota's largest rivers, which join here. The St. Croix joins the Mississippi at Hastings. Upstream, the Mississippi is joined by the Minnesota River at historic Fort Snelling. When River Warren Falls receded past the confluence of the much smaller Upper Mississippi River, a new waterfall was created where that river entered the much-lower River Warren. The new falls receded upstream on the Mississippi, migrating eight miles (13 km) over 9600 years to where Louis Hennepin first saw it and named St. Anthony Falls in 1680. Due to its value as a power source, this waterfall determined the location of Minneapolis. One tribuary of the river coming from the west, Minnehaha Creek receded only a few hundred yards from one of the channels of the Mississippi. Minnehaha Falls remains as a picturesque and informative relic of River Warren Falls, and the limestone-over-sandstone construction is readily apparent in its small gorge. At St. Anthony Falls, the Mississippi dropped 50 feet over a limestone ledge; these waterfalls were used to drive the flour mills that were the foundation for the city's 19th century growth.
Other bedrock tunnel valleys lie deep beneath till deposited by the glaciers which created them, but can be traced in many places by the Chain of Lakes in Minneapolis and lakes and dry valleys in St. Paul.
North of the metropolitan area is the Anoka Sandplain, a flat area of sandy outwash from the last ice age. Along the eastern edge of the region are the Dalles of the St. Croix River, a deep gorge cut by runoff from Glacial Lake Duluth into ancient bedrock. Interstate Park here contains the southernmost surface exposure of the Precabrian lava flows of the Midcontinent Rift, providing a glimpse of Minnesota's volcanic past.
A moraine is any glacially formed accumulation of unconsolidated glacial debris (soil and rock) which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age. This debris may have been plucked off the valley floor as a glacier advanced or it may have fallen off the valley walls as a result of frost wedging. Moraines may be composed of silt like glacial flour to large boulders. The debris is typically sub-angular to rounded in shape. Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may also occur when glacier or iceberg transported rocks fall into the sea as the ice melts.
To log this EarthCache, you must email to the owner the answers to the following questions:
1. Three rivers flow into this valley, (Mississippi, Vermillion and St. Croix); Standing where you are at the edge of the Mississippi, estimate how much deeper the Glacial River was that once flowed through the valley.
2. What four types of sediment did the Superior Lobe leave in the valley?
3. After the Mississippi River valley was filled in with sediment, how did it re-form?
4. What was the name of the Lobe that formed the drainage stream as it cut the valley the Vermillion River now rests?
5. As a crow flies how far are you from the Headwaters of the Mississippi River?
N 47° 14.384 W 095° 12.468
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