Meeting/Event Information

AIPG MN / AWG MN April Luncheon - Bedrock Geology of the Twin Cities: New insights from recent mapping!

April 03, 2018
11:30 AM to 1:00 PM
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Radisson Hotel Roseville
2540 North Cleveland Avenue
Roseville, MN 55113

The April luncheon is co-hosted by the the American Institute of Professional Geologists Minnesota Section (AIPG MN Section) and the Minnesota Chapter of the Association for Women Geoscientists (AWG MN Chapter)!

Registration for the AIPG MN Section / AWG MN Chapter April Luncheon is now open online! The cost is $21 for non-members and $16 for members when registering before Monday, April 2, 2018 at 11:00 AM. Students may attend free of charge by registering in advance. Same-day luncheon registration cost is $25.  As always, non-geologists are welcome to attend!



Bedrock Geology of the Twin Cities: New insights from recent mapping!

by Julia Steenberg, Minnesota Geological Survey


Presentation Abstract

This presentation will summarize recent Paleozoic bedrock mapping in the Twin Cities as part of the County Geologic Atlas program. Our current mapping emphasizes consistent, updated and accurate geological databases and map products that are needed for regional management of groundwater resources. Through this detailed approach, we examine a variety of datasets (outcrops, core, cuttings, geophysical logs and driller’s descriptions from water well records) to describe and identify the bedrock units, better understand the depositional framework under which they formed and map geologic structures including folds and faults. Significant improvements and modifications were made to previous maps of Washington and Hennepin counties during our most recent mapping efforts. We’ve better defined several map units, including the Prairie du Chien Group by separating it into the Oneota and Shakopee Formations. We have also reinterpreted many of the fold and fault structures that offset Paleozoic bedrock by as much as 300 feet. Major faults in Paleozoic strata approximate the traces of faults in the underlying Mesoproterozoic Midcontinent Rift bedrock as inferred from geophysical imagery, and are therefore interpreted to represent reactivation of these older structures. The timing and magnitude of reactivation can now be better constrained by the record of abrupt changes in thickness of some Paleozoic units across faults, and in depositional trends across the Twin Cities. This record is especially pronounced in the Lower Ordovician Prairie du Chien Group and younger formations.


Speaker Biography

Julia Steenberg is a geologist at the Minnesota Geological Survey who focuses on the sedimentology, stratigraphy, and hydrogeology of Paleozoic and Mesozoic bedrock in Minnesota. Since starting at the survey in 2008 she has been heavily involved in the County Geologic Atlas mapping program and has recently made geologic maps in Blue Earth, Brown, Wright, Meeker, Winona, Houston, Fillmore, and Washington Counties. Her current projects include Olmsted and Dakota counties. Julia grew up in the Twin Cities area, and holds a M.S. in Geosciences from Idaho State University and a B.A. in Geology from Gustavus Adolphus College. 


Julia Steenberg, Minnesota Geological Survey, 2609 Territorial Road, St. Paul, MN 55114,



$16.00 AIPG Member

$16.00 AWG Member Ticket

$21.00 Non-Member

$0.00 Student

$0.00 Donation to Education Fund

$250.00 2018 Section Sponsor!