Explain why liquid water is not stable on mars today, but why we nonetheless think it flowed there in the distant past.

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?

Effective charts and graphs include all of the following except 1. simple, meaningful, attractive design 2. accurate information 3.at least five different colors 5.clear presentation of information

How did geography influence the settlement of early africa.