Current Year Schedule
GSM seminars with slide show presentations are free and open to the public. They are presented by leading professionals in their fields and are aimed at learners from high school to adult. A question-and-answer session concludes each seminar. The labs, also free and open to the public, allow a hands-on learning experience and demonstrate the ideas and principles of geology and earth science. Live lectures and labs require no registration; just show up a few minutes early on the evening of the lecture.
Click on date of any seminar for attendance information and other details. For a printable version of our schedule of seminars and labs, click here.
Except as noted, in-person lectures during winter/spring 2026 are Mondays at 7:00 PM CT on the University of Minnesota campus, Keller Hall, Room 3-210. A lecture with (V) following its title is an online virtual lecture. For these, free registration is required by non-members; the instructions are supplied with the lecture description.
Our schedule is planned over 6 months in advance, so changes may occur. Always check this website shortly before each lecture for the latest seminar information.
Winter weather will come and snow might impact our lectures. The GSM will make any decision about cancelling or postponing a lecture due to inclement weather no later than 3:00 PM the day of the lecture. This information will be posted on the GSM home page (http://www.gsmn.org/). So check our home page shortly before each lecture in case there is a cancellation or a last-minute change. Also, we will e‐mail lecture postponement and cancellation information to our members.
Past seminars marked with * were recorded and the recording is available on the Geological Society of Minnesota YouTube channel. Subscribe to this channel for updates.
Seminar Details
Seminar Lab Date: November 24, 2025
Seminar Lab Subject: The Rock Elm Meteor Impact Structure, Pierce County, WI: Discovery and Basic Geology (V)
Seminar Lab Presenter: Bill Cordua, Ph.D., Geology Emeritus, University of Wisconsin River Falls
Link to Presenter https://www.mindat.org/user-32096.html
Second Link to Presenter https://minds.wisconsin.edu/handle/1793/11510;jsessionid=F27364F3C0283BDE68F8C2151FA785F7
Seminar Lab Location:
Virtual lecture 7:00 PM CT.
Participation instructions will be e-mailed to GSM members. If you are not a member of GSM and wish to attend this free seminar online, register as follows by 8 AM CT Monday, Nov 24: Go to the Contact menu above and select “Ask GSM”. In the form that appears, enter your name and e-mail address. Enter “Nov 24 lecture” in the subject line. In the message body, please enter the city and state or country from which you will view the seminar. You will receive instructions by e-mail prior to the lecture. Check your spam folder if the instructions do not appear in your in-box at least one hour prior to the lecture.
Seminar Lab Detail:
Summary: The Rock Elm structure has been recognized as a geological anomaly for well over a century, attracting prospectors, charlatans and scientists. It is interpreted as formed by an extraterrestrial impact during the middle Ordovician 430-505 Ma. Both gold and diamonds are found in unusual quantities in the alluvium of streams draining the feature. The talk will outline its basic geological features, review the evidence for its interpretation as an impact structure, speculate why gold and diamonds are associated with it and relate it to similar features in the Midwest.
Biography: Dr. Bill Cordua is a retired professor from the University of Wisconsin – River Falls where he taught geology for 40 years. He has published many technical articles and written over 100 articles for the general public on geology. Dr. Cordua is in the education division of the Rockhound and Lapidary Hall of Fame and has received the Katherine Greacen Nelson Award honoring those who have made outstanding contributions to the earth sciences in Wisconsin.