Before revision: During the 19th century terra incognita disappeared from maps of the earth, since both the coastlines and the inner parts of the continents had been fully explored.But became fully explored, even prior to the advent of aerial photography and satellite imagery in the 20th century.
After revision: During the 19th century terra incognita disappeared from maps ; both the coastlines and the inner parts of the continents , became fully explored, even prior to the advent of aerial photography and satellite imagery in the 20th century.