T188 Urban and Suburban Lakes: Paleorecords of Human Impacts and Opportunities for Geoscience Education (Posters)

Tuesday, 11 October 2011
9:00 AM - 6:00 PM
Hall C

A RECORD OF MINNESOTA SETTLEMENT HISTORY FROM RIVER LAKE

Paper number: T188-3
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

The backwater River Lake in Dakota County, Minnesota shares a hydrological connection with the Mississippi river. River Lake is part of the Katherine Ordway Natural History Study Area, a research and environmental education site owned by Macalester College and located downstream from the Minneapolis – St Paul metropolitan area. This urban lake holds the potential to record changes in agricultural and industrial development, as well as evidence of waterway modification. Students in an intermediate-level Geology course at Macalester College collected sediment cores from River Lake in January 2011 with the help of LacCore staff. Students sampled the cores and performed a variety of analyses over the course of the semester as a class research project.

Loss on ignition analysis and magnetic susceptibility analysis were performed at high resolution on a 4.27 meter long core from River Lake. Evaluation of sediment size and composition and comparison to an existing core chronology from nearby Lake Pepin suggest that the core captures the major period of residential and agricultural development in the region, extending to pre-1830. Results were compared with historical records of industrial, agricultural, and waterway development of the northern Mississippi River. Seven sections of similar core composition and nine sections of similar magnetic susceptibility were defined and placed on a preliminary age model in an attempt to isolate records of specific historical events and anthropogenic developments.