This is the first geological map of Maryland and one of the earliest American geological maps utilizing chromolithography. It covers the entire state and identifies 24 different geological types including granite, trap, coal and iron ore. Tyson based the rock classification scheme on H.D. Rogers' geological map of Pennsylvania with the New York survey names also shown. Beneath the map image are three profile views: Near Washington to the mouth of the St. Mary's River, Pennsylvania line along the Eastern Shore to Pocomoke Bay, and NW corner of Maryland due east to Hancock and the Chesapeake Bay. Published in Tyson's 1860 report to the Maryland House of Delegates (not present).

References: Marcou & Marcou #283.

Condition: B

Uniform light toning with a few minor spots and several small edge tears and separations that enter the neatline no more than 1".