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 moon has four basic phases: new moon, first quarter, full moon and third quarter. Since the moon doesn't emit its own light, it's only illuminated by sunlight. The dark section of the moon is the portion that is facing away from the sun, and only during a lunar eclipse is the Earth's shadow cast upon the moon.