Oceans 2 Geology 105 - Oceanography, Lecture 2, Earth Chapter 2 Earth and the other planets of the solar system formed from a swirling disk of gas and dust about 4.6 billion yrs ago. The earth is 4.5 - 4.6 billion yrs old based on radiometric dating of moon rocks and meteorites. On earth, the internal heat caused chemical differentiation with the dense elements, such as Fe and Ni, concentrating in the center of the earth while lighter elements and minerals were concentrated at the surface. Dimensions a slightly equant sphere. Latitude and longitude determine the location of any point on the earth.
Latitudes are lines parallel to the equator.
Longitude lines are great circles perpendicular to the equator and running thorough the poles and are measured relative to a point of reference through Greenwich, England. Annual cycles in the position of the sun relative to the tilt of the earth's axis cause the change of seasons. Water travels through the hydrological cycle in which it evaporates from the ocean, precipitates over land, runs off into the ocean where it begins a new cycle.