Potomac River, xi, 16 (ill.); channels, tributary, 101; Lower Cedar Point, spit, 87 (ill.); Popes Creek and, 83 (ill.); Powells Creek and, 93 (ill.); Quantico Creek and, 95 Potter, Lieutenant, opp. 74 Powells Creek, Virginia, 93 (ill.), 101 Put-in-Bay, 72, 73 (ill. and map) Quantico Bay, 95 (ill.) Quantico Creek, 95 (ill.) Rahbeg, Arabia, 101 Railroads, 23 Randalls Island, 15 (ill.) Ray filter, 102 Reconnaissance work, 69, 71 Red River, Texas-Oklahoma, 50, 51 (ill.) Relief, means for showing, 5; representation on maps, 66 Revision of maps, 79 Richmond, Va., Monument Ave., etc., 12 (ill.) Rivers, 22; Plains--Red River, 50; miniature system, 33 (ill.) Roads, 23 Roberts Creek, Virginia, 94 (ill.) Rochester, N. Y., 2, opp. 74 (ill. and map) Rochester, N. Y., topographic sheet, opp. 74 Rockaway Beach, Long Island, 11; part, showing development, 17 (ill.) Rocks, Florida coast experiment, 93; sedimentary, 69, 70 (ill.); study of, 69 Royal Arches, California, 60 (ill.) San Joaquin Hills, California, 68 (ill.) Sand bars, 45, 46 (ill.); Cape Charles, Virginia, 99 (ill.); Far Rockaway, Long Island, 100 (ill.) Sandy Hook, N. J., 78 (ill.) Santa Monica, Cal., 65, 66; map of region between Los Angeles and, 67 Santa Monica Mountains, 57, 66 (ill.), 67 (map) Santa Monica, Cal., topographic sheet, 67, 79 Scale in vertical photographs, viii, 74 Schoolcraft, Mich., 54 (ill.), 55 (map), 56, 72; kettleholes near, 56 (ill.) Schoolcraft, Mich., topographic sheet, 53, 55 Seashore, 22 Sedge grass, 29, 30, 38 Sentinel Rock, 60 (ill.) Sepulveda Canyon, California, 66 (ill.), 67 (map) Sevenmile Beach, New Jersey, spit and shoal, 98 (ill.) Severn River, Virginia, 7, 9 (ill.) Shadows, 5, 61 Shark River Inlet, New Jersey, 82 (ill.) Shasta, Mt., 57, 58 (ill.); glacial gorge on, 59 (ill.) Shipyards, 11; Newport News, 14 (ill.) Shoals, 45, 84 (ill.), 85, 94 (ill.); Hereford Inlet, New Jersey, 98 (ill.); Miami, Fla., 96 (ill.), 97 (ill.), 102 Shore features, 83 Shrubbery, 13 (ill.) Sierra Nevada Mountains, Cal., 62 (ill.), 63 (map) Silt, 29, 36, 39 Simi Hills, California, 65 (ill.) Simons, J. W., Jr., xi Sky, cloudy and overcast, 49 Spa Creek, Maryland, 7, 9 (ill.) Spits, lines of growth, Tucker Beach, New Jersey, 91 (ill.); recurved, 88 (ill.), 89 (ill.), 90 (ill.); Sevenmile Beach, New Jersey, 98 (ill.); simple spit, 87 (ill.) State-War-Navy Building, Washington, D. C., 16 (ill.) Stereoscopic camera, 6 Stevens, A. W., opp. 74, 89 Stone Canyon, California, 66 (ill.), 67 (map) Stonington, Conn., 92 Stove Point Neck, Virginia, 46 (ill.), 47 (map) Stream channels and mud flats, 41, 42 (ill.) Streams, development in tidal marsh, 28 (ill.) _See also_ Rivers Submarine geography, 45 Submarines, 101 Submerged land forms, 45 Submerged objects, detection, 101 Sunken mines, 101 Sunlight, 49 Surface, general aspects as seen from the air, 22 Swamps, 27