For Washington, D.C., inhabitants or anyone planning a trip to the area, interesting information on the hydrology, geology, and natural and cultural history is available.

To provide geographic and historical background for field trips in the area, a book was published for the 28th International Geological Congress, held in Washington in July 1989. Geology, Hydrology, and History of the Washington, D.C. Area, edited by John E. Moore of the U.S. Geological Survey, Reston, Va., and Julia A. Jackson of the American Geological Institute, Alexandria, Va., describes such interesting items as the Washington Canal, which ran from the Potomac River to the Capitol and is now Constitution Avenue, and the Cabin John Aqueduct, where a 297-foot granite arch was the longest masonry arch in the world for 40 years. The aqueduct has carried water to Washington since 1863. The 114-page book contains many historic photographs and maps and can be purchased from the American Geological Institute, 4220 King Street, Alexandria, VA 22302-1507, tel. 703-379-2480.