Unfortunately that's how the data is provided [1]. Maybe because the Great Lakes were carved by geologically recent glaciation, and the model is built off tect

Unfortunately that's how the data is provided [1]. Maybe because the Great Lakes were carved by geologically recent glaciation, and the model is built off tectonic plate movement. A writeup of the methodology is available if you're interested. [2] [1] https://www.earthbyte.org/paleomap-paleoatlas-for-gplates/ https://www.earthbyte.org/paleomap-paleoatlas-for-gplates/ [2] https://drive.google.com/file/d/1-q0WIa7ofISFHyBe4UxvN8DIPs82SPmS/view?usp=sharing https://drive.google.com/file/d/1-q0WIa7ofISFHyBe4UxvN8DIPs8...