Laserfiche WebLink
suggest an erosional. channel in the bedrock surface that was subsequently filled by unconsolidated <br />deposits. It is likely that this channel was formed by meltwater during the last glaciation and became <br />a tributary to the ancestral Mississippi River. It was subsequently filled by glacial deposits. The <br />preponderance of sand and gravel in Elk River suggests that the fill material is likely glacial outwash <br />deposits (sand and <br />to bedrock) shown <br />on Figure 4 corresponds approximately to the areas where the Eats Claire Formation has been eroded <br />away and the first bedrock unit is the Mt. Simon-Hinckley Formations, ash shown on Figure 3. <br />Unconsolidated glacial drift deposits are typically heterogeneous. In one location, the unconsolidated <br />deposits can be mostly sand or gravel and in a nearby location, only clay may be found. "these abrupt <br />changes from sand to clay in glacial deposits makes siting wells difficult in some locations because it <br />is difficult to predict how much water a well in these deposits might yield. Using the Minnesota <br />P:\Mpls\23 MN\7l\2371105 Water Supply Alternative Study\FinalDeliverables\Alternatives_Report_final.doc 9 <br />Figure 5 Aerially Averaged Percentage of Sand or Gravel in Unconsolidated Deposits <br />