Mapped by United States Geological Survey ( USGS ) from ground surveys and U . S . Navy air photos, 1959-66.
32.
Mapped by United States Geological Survey ( USGS ) from ground surveys and U . S . Navy air photos, 1961 67.
33.
It was mapped by the United States Geological Survey from ground surveys and U . S . Navy air photos, 1959 66.
34.
A Globe on-the-ground survey of 14 sites, and a review of scores of others, found the toll almost certainly surpassed 1, 000 dead.
35.
It was mapped by United States Geological Survey ( USGS ) from ground surveys and U . S . Navy air photos, 1959 71.
36.
It was mapped by the United States Geological Survey ( USGS ) from ground surveys and U . S . Navy air photos from 1960-63.
37.
It was mapped by the United States Geological Survey ( USGS ) from ground surveys and U . S . Navy air photos from 1961-66.
38.
From a ground survey, the Corps had identified nine breaches that must be repaired to provide a minimum level of protection to the affected parishes.
39.
Of course, targets had to be accurately located, but by 1916, air photo interpretation techniques enabled this, and ground survey techniques could sometimes be used.
40.
Rutgers Glacier was mapped by the United States Geological Survey ( USGS ) from ground surveys and aerial photographs taken by the United States Navy.
