The geological column is supposed to represent a vertical cross-section through the earth’s crust, with the most recently deposited (therefore youngest) rocks at the surface and the oldest, earliest rocks deposited on the crystalline rocks at the bottom.
Where would you go to see this geological age system? Not in nature—only in the textbook.
The text by Brown, Monnett and Stovel (Introduction to Geology) explains why:
There is no place on the earth where a complete record of the rocks is present… To reconstruct the history of the earth, scattered bits of information from thousands of locations all over the world must be pieced together. The results will be at best only a very incomplete record. If the complete history of the earth is compared to an encyclopedia of thirty volumes, then we can seldom hope to find even one complete volume in a given area. Sometimes only a few chapters, perhaps only a paragraph or two, will be the total geological contribution of a region; indeed, we are often reduced to studying scattered bits of information more nearly comparable to a few words or letters.
In other words, there is no complete geologic column at any one place on the earth.
