Geology and the dating of rocks is not part of evolutionary theory. That the Earth was much older than a literreading of Genesis allowed had been established by the time Darwin wrote _On the Origin of Species_
Although the following points are not really part of evolution they are common creationist errors that are relevant to discussions of the fossil record:
There is no circularity in the use of fossils to date rocks. Certain fossils - called "Index fossils" are identified as good indicators of age, and only then are they used as a quick and simple method of dating other rocks.
Radiometric dates often do NOT require knowledge of the initial amount of the daughter isotope. Isochron methods in fact will tell you what the number is.