In 1852 he went to the Victorian goldfields, and subsequently became a clerk, first in the Post Office, Melbourne, and afterwards in the county court.
Having resigned his clerkship, he pursued a bush life, and in 1872 made his first effort in the field of exploration.

His party was a small one, the funds being found by contributions from S.Carmichael, one of the party, Baron von Mueller, Giles himself, and one of his relatives.

The members of the expedition were Giles, Carmichael, and Robinson; 15 horses and a little dog were included in the equipment.

They started from Chambers Pillar, and it was on this journey that Lake Amadeus and Mount Olga were discovered, the two most enduring physical features whose discovery we owe to Giles.

The lake is a long narrow salt-pan of considerable size, but without any important affluents; Mount Olga is a singular mountain situated about 50 miles from the lake.