crownedrose:

jtotheizzoe:

cetacean34:

Ray Troll stratigraphy/geologic time. I’m printing this out and hanging it above my desk. 

Know your geologic history.

And don’t put a nautilus in the back of your pickup truck. That is not how we treat nice fossils.

Actually, there’s a lot wrong with this chart. I see it’s written as the K-T boundary instead of the K-Pg, though I’m still getting used to the change myself. But when it comes to periods and epochs, some are there, and some are not. Here are the issues:

Where’s the Paleogene period on this chart? After the Cretaceous period, it jumps right to the Paleocene, which is the first epoch (of three - followed by the Eocene and the Oliogcene) in the Paleogene period. The Paleogene period is in the Cenozoic era, so why is it missing on this chart?

If you include epochs, you must include what period they reside under, otherwise this chart now makes it out to be that the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Piestocene, and Holocene are all periods when they are in fact epochs.

The other period is missing here that resides in the Cenozoic era as well, the Neogene. The Neogene had two epochs: the Miocene, and Pliocene, which are seen above.

For the Piestocene and Holocene epochs, they reside in the Quaternary period. Yes, all these epochs are within the Cenozoic era, but again, you must include their periods as well, and for the Mesozoic, you should include their epochs, etc. This chart would be confusing to one who does not know the divisions.

This same issue is also occurring at the bottom of the chart. The Palaeozoic era includes all those listed, but instead of having the Mississippian and Pennsylvanian subperiods listed, why wouldn’t one just put the Carboniferious period instead? I know some just use the M and P subperiods, but I prefer the Carboniferious!

To sum it up: epochs and periods are not the same, and even if many of us know our geological time charts, there are many people who would most likely confuse the terms because of this chart’s layout. If you’re still unsure of what I meant by all of what’s stated above, check out this geologic time scale on Wikipedia, which is a more accurate and easier to understand chart.