I just finished reading a lyrical article by John McPhee in the March 12 New Yorker
about, among other things, the great chalk beds of northern Europe. Seek it out and enjoy the way McPhee weaves the human and the geological together. Chalk is largely unknown in the United States, but it's a key ingredient in European lifeways and commerce. All I can do now is gaze at my gallery of limestones
and think of England.
UPDATE: Perhaps I should think of Kansas instead, where Ron Schott points out there is plenty of chalk. All over the Plains states, in fact. But the east (at least the northeast) and west have littleas McPhee points out in his article (and as I mention in connection with aragonite), chalk forms only during certain geologic periods, depending on the magnesium in seawater.