Answer:Geographic featured that acted as norther borders of the Roman Empire at its height were: Rhine River, Danube River, Carpathian Mountains, and the Black Sea.
The basic theory of plate tectonics is that along seafloor spreading zones, the continents are separating from one another. As they spread apart, magma comes to the surface and becomes new continental crust. As the tectonic plates move away from spreading zones, they collide with one another.
Organization of Petrochemical Exporting Countries
