Under the feudal system of medieval europe, land was exchanged for gold

The “twelve apostles” are in which national park?

What is the border between layers a through f and layer g called?

Tides are caused by a differences in the gravitational force of the sun at different points on earth. differences in the gravitational force of the moon at different points on earth differences in earth’s gravitational field strength at different points on earth’s surfac fluctuations in the gravitational attraction between earth and the moon.