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.
Near side of the moon, as seen through a telescope. The moon looks round, but it isnât. In a dark sky, the moon looks bright white, but this image captures its true asphalt gray color. Notice that the moonâs near side has dark âmariaâ or âseas,â while the moonâs far side (photo at top of post) lacks these features.