Reconstruction of isostatically adjusted paleo-strandlines along the southern margin of the Laurentide Ice Sheet in the Great Lakes, Lake Agassiz, and Champlain Sea basins

Strandlines document the former presence of lakes and a sea in east-central North America along southern margin retreating Laurentide Ice Sheet (LIS). The strandlines these formerly level water bodies are uplifted to north provide evidence glacial isostatic adjustment (GIA) Earth’s crust ice load. We compile published ages measurements present elevation location shore features eight major paleo-water from St. Lawrence Valley northern Great Plains digital format as an aid for numerical modelling GIA. Data eastern were extracted digitized publications during past 120 years. Digital position coordinates scaled maps survey sites or determined using Google Earth Pro software. Published data paleo-lakes Duluth Agassiz mainly obtained field models. Two-sigma 95% probability values provided strandline isobase (contour) positions representing deformed surfaces. Peak gradients reported here largest at about ca. 13 000 years ago. Lower older shores may reveal areas closer peripheral bulge thinner (lighter crustal loads). Concave upward profiles characterize most paleo-basins, whereas linear uplift profile characterizes Champlain Sea strandline. Directions maximum within body basins point toward thickest part LIS near Quebec–Labrador dome.