Geologic time rock dating
In fact, sedimentary rocks are, in a sense, trash from the Earth's surface deposited in basins.
Principle of Original Horizontality Sedimentary strata are deposited in layers that are horizontal or nearly horizontal, parallel to or nearly parallel to the Earth's surface.
Thus, if the strata are later uplifted and then cut by a canyon, we know that the same strata would be expected to occur on both sides of the canyon.
Principle of Inclusions If we find a rock fragment enclosed within another rock, we say the fragment is an inclusion.
If the enclosing rock is an igneous rock, the inclusions are called xenoliths.
Prior to the late 17th century, geologic time was thought to be the same as historical time.
Archbishop James Ussher of Armagh, Ireland, 1654, added up generations from the Old Testament and determined that Earth formed on October 23, 4004 BCE.