What might explain why texas settlements did not extend further to the northwest?

The three sociological perspectives include the beginner’s mind, culture shock, and the sociological imagination

If you mean how the great lakes formed, then  the great lakes began to form at the end of the last glacial period 14,000 years  ago, ice sheets  retreated, which led to exposing the basins they had carved into land which then filled with melt-water.