This article is written to explain to people what a geologic column is and how creationists always tell untruths about.
What is a Geological Column?
From Glossary of Geology, American Geological Institute, Fourth Printing 1977:
Geologic column: (a) A composite diagram that shows in a single column the subdivisions of part or all of geologic time or the sequence of stratigraphic units of a given locality or region (the oldest at the bottom and the youngest at the top, with dips adjusted to the horizontal) so arranged to indicate their relations to the subdivision of geologic time and their relative positions to each other.
(b) The vertical or chronologic arrangement or sequence of rock units portrayed in a geologic column.
Normally geologists refer to time tables when referring to time scales or stratigraphic columns or tables when they refer to rocks in an area, but I won’t discuss this here.
What do creationists make of “the” geologic column?
“The” geologic column (as creationists call it) is referenced to something similar to found in this link:
Note that “The” geological column indicates time, not “rocks”, nor thicknesses. Just time and how we name the different time “periods”.
Creationists tend to tell that each of those time periods refer to “one rock layer” and is “supposed to be theoretically x metres thick”. Then they also tell untruths about “geologists using evolutionary assumptions” for “The” Geologic Column.
And then "polystrate" fossils are mentioned, too.
Which, of course are all ridiculous untruths they keep on spreading.
The way “the” geologic column was compiled.
This compilation started in 1669, with Steno’s superposition principle (basically that Sedimentary layers are deposited in a time sequence, with the oldest on the bottom and the youngest on the top). Quite logical. Gravity.
“The” geological column was compiled with the aid of the fossil species found in rocks; especially with the use of index fossils who were of great value.
An index fossil basically is:
Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. The best index fossils are common, easy-to-identify at species level, and have a broad distribution—otherwise the likelihood of finding and recognizing one in the two sediments is minor. (Altered Wiki article)
They even have pictures of some index fossils.
These relative ages of the rocks were compiled by comparing which fossils were above which fossils; daisy-chaining around the world and giving these time-periods names. Any Ordovician fossil is thus younger than a Cambrian fossil, because Ordovician fossils occur above Cambrian fossils if you dig down.
What this means is that, for example, the Cambrian "Epoch" consists of thousands of “layers” of rock; different rocks in different parts of the world, and can also consist of lots of layers stacked one on the other at one location. All those “rocks” containing the same “index fossils” and are named “Cambrian”.
The name “Cambrian”, thus, does not reflect a rock or rocks or layers of rock, but a time period. When a geologist refers to “Cambrian strata”, they thus refer to a time period. (Exactly like a teenager is not 13 and 14 and 15 and 16 and 17 and 18 and 19 years old, but has an age falling in the teens).
For information on how and when all these time periods were compiled in sequence of age, here is a good link. The names of the persons who described the different major time periods as well as the date they did it can be seen there.
Of all the major "Epochs" containing life, recognized today, only the Paleocene, Ordovician and the subdivisions of the Precambrian, were described after Darwin published in 1859. Everybody can thus see that the vast bulk of the geological column was thus configured before Darwin wrote “The Origin of Species”. That’s how he could use the fossil succession as evidence for evolution by means of natural selection. Evolution is the fact; natural selection is the theory.
These time periods were confirmed with the advent of absolute dating methods, such as radiometric dating, in the middle of the last century. Those showed that our relative dating was correct, but also gave us absolute dates. For example, the Cambrian lasted from around 600 million years ago to around 505 million years ago, thus a period lasting around 95 million years.
Next time some creationist, such as, Sydney.a.daniel, lies to you, tell him he is telling complete untruths. Laugh at him.
Comment from Sydney.a.daniel, January 29, 2013 at 17:58
Here is some more proof of a Creator/God:
The Fossil Record...Evolutionists have constructed the Geologic Column in order to illustrate the supposed progression of "primitive" life forms to "more complex" systems we observe today.
The vast bulk of “The” Geologic Column was constructed way before Darwin wrote his wonderful book. The evolution of life is a fact, as witnessed by “The” geological column. Darwin used it as evidence for his theory of the origin of species by means of natural selection.