It measures 3 miles from E. to W. and 2 miles from N. to S., has an area of about 3500 acres, and is 7 miles in circumference. Except at the landing place on the south-east, the cliffs rise sheer out of deep water, and on the north-east side the highest eminence in the island, Conagher, forms a precipice 1220 ft. high. St Kilda is probably the core of a Tertiary volcano, but, besides volcanic rocks, contains hills of sandstone in which the stratification is distinct.
Continuously populated since prehistoric times, the original inhabitants were evacuated in 1930 due to disease and outside influences.