DOC PREVIEW
U of M GEOL 3000 - Washington Co Surficial Maps

This preview shows page 1 out of 2 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Geol 3000 Name___________________________Geologic Maps Score ________/12Surficial (and Bedrock) Geology of Washington County, MinnesotaRefer to the Surficial Geology and Bedrock Geology plates of the Washington County Atlas (MGS County Atlas Series C-5, 1990) to answer the following questions. Each question is worth 0.5 pts.1. General Glacial HistoryA) The Superior and Grantsburg lobe deposits are part of what phase (or stage) of Pleistocene glaciation? ________________________________B) Which lobe deposit is older? ____________________C) What evidence for the age relationships of the lobes is portrayed in the A-A’ and C-C’ cross section? _______________________________________________________________________2. Pre-Wisconsinan DepositsA) What might be one of the attributes distinguishing Superior till from Keewatin till? ___________________________________________________________________________B) What unit’s age is inconsistently portrayed on this map when comparing the Description of Map Units, Cross Section C-C’ and the Correlation of Map units? _________________________3. Superior Lobe DepositsA) What unit forms the main till deposit of the Superior Lobe? ___________ B) What is the name of the moraine formed by this till unit? ______________________ C) What unit forms the main outwash deposit of the Superior Lobe? _____________ D) Given the relative distribution of these two units, which direction was the meltwater draining away from the Superior Ice Lobe? _________ E) Unit sl represent deposits formed in what type of depositional environment?___________________F) Superior Lobe esker landforms are typically associated with what map unit(s)?_________________4. Grantsburg Sublobe DepositsA) From what larger ice lobe did the Grantsburg sublobe eminate? ____________B) As one progresses to the SE across the Grantsburg sublobe deposits, what is the general progressionof surficial materials? ________________________________________________________C) Oneka Lake is the last vestige of a larger pro-glacial lake. What unit forms the lake bed of that larger lake? __________________5. Terrace DepositsA) How do successively formed terraces change in terms of elevation?_______________________B) How are successively formed terrace positioned relative to the current floodplain? _________________________________________________________________________________C) What is the significance of the blue stippled areas of the terraces? _____________________________________________________________________________________________________________D) Note that the St. Croix River is noted as Lake St. Croix upstream from Point Douglas (where it merges with the Mississippi River) to about Stillwater. Can you think of why the lower St. Croix is backed up as a lake? ______________________________________________________________________________________________________________________________6. Postglacial depositsA) Organic deposits (o) commonly flank what type of units in both the Grantsburg and Superior lobe deposits? _____________________________B) In glacial times, what type of botanical entity do the organic deposits represent?________________C) Note that some elongate organic deposits are hosted within terrace deposits. In what specific type of lacustrine environment might these organic deposits have formed? ______________________7. Bedrock geology A) The long ribbon of unit Cj in the southern part of the county represents what type of topographic feature? ______________________________________________________________________B) How does this feature relate to the glacial deposits overlying it?________________________________________________________________________________________________________C) Some lakes in the area are remnants of proglacial lakes (e.g. Oneka Lake), formed by damming behind a moraine, and many others are kettle lakes, formed by the melting of large ice blocks embedded in till or outwash. There is a third type of lake represented by Lake Elmo in the south and a string of lakes in the northeastern part of the county (Big Cameron Lake, Square Lake, Mays Lake, Terrapin Lake, Long Lake, and Big Marine Lake). Looking at the locations of these lakes relative to the underlying bedrock, how might these types of lakes have formed?


View Full Document

U of M GEOL 3000 - Washington Co Surficial Maps

Download Washington Co Surficial Maps
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Washington Co Surficial Maps and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Washington Co Surficial Maps 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?