In the southwest which mountainas stretch across the isthmus that separates the black and caspian seas?

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.

Alow-pressure belt means the air is cold and dry warm and rising cold and sinking warm and moist

The oldest seafloor in the atlantic ocean is located closest to the edge of the continents. explain how this age can be used to figure out when north america first began to separate from europe