Here Be Dragons: Maps on the Geological History of the United States

I previously posted on Codex 99's two part series on the development of the US "National Atlas," and one interesting thing I noticed were the changes in the geological maps of the US.  The geological history of the US has not changed.  So what has changed is what is understood or, more exactly, what is reported as fact since no unknowns or margins of error was reported with these maps. They are printed as known and exact knowledge, when it is evident that (at least until recently) that knowledge was quite inexact.

Here are three geological history maps featured in Codex 99's series, as an example (click to expand):

1874 map

1970 map

2012 map

Of course, the amount of our knowledge has increased, and improvement is to be expected. We should also ignore stylistic differences. What I fault is the failure to note guesses and extrapolations: the earlier mapmakers but forward definite lines. There's a long history of course of misleading maps; maps give a sense of certainty but sometimes warrant caution. HC SVNT DRACONES or something. Ah well.