• Shorelines of postglacial Chicago Lake
• Younger Dryas coniferous wetlands
The Brewster Creek Site is within Pratt’s Wayne Woods Forest Preserve in Dupage County, near Bartlett, Illinois (Fig. 1). The site was originally a wetland that was drained for agriculture by installation of tiles. A restoration project to remove the tiles and restore the wetland was planned for the early 2000s. Dr. Brandon Curry (Illinois State Geological Survey) cored the site in 2003 and found numerous wood fragments and larch needles. Removal of tiles commenced in 2005, and a survey trench was dug (Photo 1), revealing the stratigraphy and the presence of wood fragments (Photo 2). We visited the site on June 3, 2005, just before the trenching and removal of tiles at the end of the month. Buried logs of larch and spruce (8-5 cm in radii) were found in a 25-cm thick peat between two marl layers. Radiocarbon dating of wood from the peat suggests that the peat has been accruing from 12,920 to 10,260 Cal Yrs BP (Fig. 2). Seven out of 15 collected specimens were crossdated into a 65-year tree-ring width record of larch with calendar age between ca. 12,380 and 11,750 Cal Yrs BP (2 sigma).