What is "strata-dome"

The Strata-Domes were a fleet of five streamlined dome cars operated by the Baltimore and Ohio Railroad ("B&O"). The term referred both to a pair of dome cars constructed by Pullman-Standard and three Budd Company domes the B&O acquired from the Chesapeake and Ohio Railway ("C&O"). They were the first dome cars operated in the Eastern United States, following on the success of the Chicago, Burlington and Quincy Railroad's "Vista-Domes" in the west. The cars entered service in 1949 and were all out of regular service by 1981. Several have been preserved.