Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation is also known as the ocean's conveyor belt (which refers to deep ocean density driven ocean basin currents). These currents, called submarine rivers, flow under the surface of the ocean and are hidden from immediate detection.
The light-colored material is in areas of the Moon called the highlands, which represent the earliest crust on the Moon. Impact cratering shattered this crust and often deformed it, pushing some of it into mountain-high impact crater rims or ejecting it across the surface of the Moon.
The mountainous region is situated between the altitude of 4877 to 8848 meters in the northern part of the country. The hilly regions lies at the altitude of 610 to 4877 meters in between Terai and Mountainous regions. Therefore, the geographical structure, climate, vegetation etc. are different.