Fig. 77—The underwater channel in Quantico Bay. Quantico Creek is a tributary of the Potomac River entering from the Virginia side, about 28 miles downstream from Washington. The “Bay” is the widened part of the stream at its entrance into the Potomac, which is entered by the tide. Forested land appears at the right and left, with light-colored fields at the left. The space between the wooded areas is occupied by shallow water, beneath which appears the relatively deep channel, which forks after the manner of streams. The branching channel is wholly under water and differs in some respects from the channel of a normal stream. Among the more obvious peculiarities is the “fanning out,” of the headwaters. Photograph taken from a height of about 18,000 feet. Scale, about 1:21,000.
Fig. 78—Natural channels and shoals near Miami, Fla.: an oblique view eastward to the ocean across Bear’s Cut, which is situated between Biscayne Key and Virginia Key. Because of the greater depth of water, the channels with a maximum depth of 17 feet appear darker than the shoals. The photograph was taken at a height of 3,000 feet, April 20, 1918.
Fig. 79—A dredged channel at Miami, Fla.: an oblique photograph showing part of the city, the boat landing, the sandy beach, and the shallow water, through which a straight ship channel has been cut, which appears dark-colored in the illustration because of the greater depth of water. The photograph was taken April 22, 1918, from 21 height of 3,000 feet.