This
secondary sandstone is sometimes more or less calcareous. I believe it
is used for a cement by the Canal Company, which hardens under water.
Will you do me the favor to settle this question?
"On your way to Detroit, you may perhaps, without material
inconvenience, collect facts of importance to me, in relation to
secondary and alluvial formations. Anything transmitted to me by the
middle of April on these subjects will be in season, because I shall not
have printed all the transition part before that time.
"Have you any knowledge of the strata constituting Rocky Mountains? Is
it primitive, or is it graywacke like Catskill Mountains? I have said,
in a note, that, after you and Dr. E. James set foot upon it, we shall
no longer be ignorant of it.
"I intend to kindle a blaze of geological zeal before you return. I have
adapted the style of my index to the capacities of ladies,
plough-joggers, and mechanics."
_March 28th_.--While here, I received a notice of my election as a
member of the Academy of Natural Sciences at Philadelphia.
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