Geologic time.

-GEOLOGIC TIME-     Before i show you the geologic scale, I just thought I would throw in some information; The geologic scale displays all of the different bits and chunks off time that has been since the earth first became the earth. In these scales you can see eons, eras, periods, epochs and ages. The ones who first thought we should have one of these scales were the miners 1500s and the 1600s. they wanted, and needed, to understand geological relationships of different rock units were miners. Mining had been of commercial interest since at least the days of the Romans. Nicolaus Steno, in 1669. noted the relationships of the different rock units as he described two basic geologic principles. The first one said that sedimentary rocks are laid in a horizontal manner And the second one said that the younger rocks were deposited on the older ones. If this is "complicated" to understand imagine this; You are painting a wall, the older layers were put on first, hence, it will find itself at the bottom, while the newest layer finds itself on the top. And then in 1795, James Hutton added an additional concept which was then later emphasized by Charles Lyell sometime in the early 1800s. This basically says that the natural geologic processes uniform  in frequency and magnitude throughout the time that passes. This idea is known as the "principle of uniformitarianism"