—Prof Edward Hitchcock, 1828
All 50 of the American states have agencies that deal with their rocks, soil, water, and mineral wealth; lots of these are called "geological survey." It's a name with a long history, dating from the young days of the American nation when the states were few and the territory of the country was largely unknown.
The first geological surveys were just that—one-time efforts to map the state's rocks, especially the public lands, so the state could give away its lands and collect taxes on the most valuable resources. North Carolina funded the first in 1823, a $250 stipend for a single geologist. Edward Hitchcock headed the first real state geological survey, with salaried employees, in Massachusetts in 1830. Tennessee started one the next year, and quickly thereafter most of the existing states funded surveys of their lands.
The idea of a geological survey was not new, but it wasn't sexy until the 1820s. Before then, the USA's major earth resources were considered to be timber, agriculture, coal, and base metals—iron, lead, copper. But what made the states prick up their ears was the discovery, up and down the southern Appalachian Mountains, of gold. (Long before California's Forty-Niners, the first American gold rushes were in the eastern states.)
The benefits of the surveys being so great, many of them turned into permanent agencies. This is good, because it's not enough to map the rocks once. Advances in science, changes in the economy and changes in public needs make a state's resources a different picture every year. And there's more than one way to map a state's geology: mineral producers want one thing, water managers another and land-use planners still more.
Many other state surveys have winked in and out of existence, or had periods of near-eclipse when the State Geologist had no more prestige—and funding—than the state poet laureate. But today, and for now, all 50 states support state geologists and agencies to go with them. (The Association of American State Geologists is their very exclusive club.)
The federal government got into the act in 1879, and the United States Geological Survey eventually became the world's premier earth-science agency.
So, did Hitchcock's vision come to pass? Well, the states all publish geologic maps and pamphlets, for free or very cheaply. But when I set out in 1998 to put geologic maps for all 50 states online, I found only about half of them—and of these only 15 were posted by state geologic agencies. Since then much progress has been made; the National Geologic Map Database is the best place to follow the state of the art. There you'll find free GIS databases, links to purchase maps, and other useful products.
These large products are excellent for people who need them to do business, and quite in keeping with the state's mission. But for students and teachers they are too hard and too much. For simple public education, a more citizen-friendly approach is to mount a clickable map that gives you close-ups or explanations of the different rock formations. Kentucky's, because it's based on a simplified geologic map, works fast and is good enough for the needs of most users. Minnesota furnishes specialized maps of bedrock, glacial deposits (which cover much of the state's bedrock), and various geophysical features.
I have collected the best maps I've found for that basic purpose in this A-to-Z gallery, the first and still the only place on the Web where you can access a geologic map of every state as a simple, straightforward image. But back when some of the states were being so slow, I got hold of printed maps and scanned them myself. Those are still here, and even today some of them are unique to this site.
