Answer:
Because time varies with change in longitudes
Ultramafic,as components of mafic rocks like olivine and pyroxene solidified at very high temperatures, so mafic minerals will decompose as the result of chemical weathering more rapidly than felsic minerals
Answer:
The most highly developed geocentric model was that of Ptolemy of Alexandria (2nd century).
I would say the topic of such a study would be paleomagnetism and perhaps its effect on plate tectonics because when the seafloor spreads at the mid-ocean ridges, magnetized stripes of rock, symmetrical on either side of the trench form and they record changes in the earth's magnetic poles at certain times so can be dated to help show the rate of spreading of the seafloor at these locations.
