It has been possible to observe continental drift directly with GPS satellites: GPS Time Series Furthermore, GPS-measured rates agree rather closely with continental-drift rates over the last several million years: Global Tectonics and Space Geodesy -- Gordon and Stein 256 (5055): 333 -- Science The latter sort of estimate gets its time values from radiometric dating, so GPS measurements provide a good check of them.

While when summers are hot, the glaciers will melt more than they are supplied, and the glaciers will retreat.

This means that a low obliquity and an obliquity-summer orbit winter will begin an ice age, while a high obliquity and an obliquity-summer orbit summer will end an ice age.

When the Earth is closest, it has an overall "orbit summer", while when it is farthest, it has an overall "orbit winter".

This is in addition to the familiar "obliquity summers" and "obliquity winters" that the northern and southern hemispheres get in opposite phase..

Some people have worked on parts of the Paleozoic; coverage there is still rather patchy.

Status: Neogene - 20 mya - done Paleogene - 65 mya - almost done Cretaceous - 145 mya - some gaps Mesozoic - 251 mya - more gaps Paleozoic - 542 mya - very patchy The study of "sunquakes" (Wikipedia) has made it possible to test theoretical models of the Sun's internal structure, because some sunquake modes penetrate deep into the Sun's interior.The two winters and summers now coincide in the Southern Hemisphere. Since the Earth's orbit as well as its spin precesses, that causes the Earth's obliquity to vary between 22.1 and 24.5 degrees. It controls the intensities of the obliquity summers and winters, the greater obliquity being the more intense.Big ice-age glaciers need continent to form on, and at this time, it is the northern hemisphere that has the most midlatitude continent.This causes their orbit north poles to precess backward around the Solar System's angular-momentum vector, and their eccentricity vectors to precess forward.The eccentricity vector is eccentricity * (perihelion direction).Jesus, Mousa) and religions (Christianity, Judaism, Buddism) Al Islam - Official website of Ahmadiyya Muslim Community - an Islamic organization, international in its scope, with branches in over 200 countries.