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<blockquote data-quote="weambulance" data-source="post: 959367" data-attributes="member: 7174">Well the stones aren't dolerite if they're made of dolomite, they're dolostone. Dolerite is an igneous rock that does not have dolomite in it. But anyway, if the rocks are dolostone looking at erosion is a fairly decent method of guessing how long since the rocks were broken, which happened after they were cut. So they're establishing a boundary on the near end of the age.Dolomite is a magnesium carbonate mineral that erodes fast on a geologic scale because meteoric water, which is a fancy way of saying rain, is acidic. You have to work with a pile of assumptions that may or may not be correct to guess at how long ago those rock pieces were separated, like CO2 levels in the atmosphere over time and how much rainfall there was, but getting within 10,000 years of the real date seems plausible.You can't radiocarbon date rocks, for general information. Most rocks have no carbon in them to begin with, and radiocarbon dating is only good for things about 50,000 years old anyway, which is to the earth as a few hours are to humans. Geologists use many different methods to date rocks, some similar to radiocarbon dating (K-Ar dating), some quite different.</blockquote>

[QUOTE="weambulance, post: 959367, member: 7174"] Well the stones aren't dolerite if they're made of dolomite, they're dolostone. Dolerite is an igneous rock that does not have dolomite in it. But anyway, if the rocks are dolostone looking at erosion is a fairly decent method of guessing how long since the rocks were broken, which happened after they were cut. So they're establishing a boundary on the near end of the age. Dolomite is a magnesium carbonate mineral that erodes fast on a geologic scale because meteoric water, which is a fancy way of saying rain, is acidic. You have to work with a pile of assumptions that may or may not be correct to guess at how long ago those rock pieces were separated, like CO2 levels in the atmosphere over time and how much rainfall there was, but getting within 10,000 years of the real date seems plausible. You can't radiocarbon date rocks, for general information. Most rocks have no carbon in them to begin with, and radiocarbon dating is only good for things about 50,000 years old anyway, which is to the earth as a few hours are to humans. Geologists use many different methods to date rocks, some similar to radiocarbon dating (K-Ar dating), some quite different. [/QUOTE]

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