The southern section of the Bay near the Heads is covered by extensive sand banks, known as the "Great Sand". A shipping channel was dredged in an east-west direction from the Heads to near Arthur's Seat late in the nineteenth century, and maintained ever since. Early shipping used piers at Sandridge (Port Melbourne), but later moved to various wharves along the Yarra River, which make up today's Port of Melbourne. The Melbourne Harbor Trust and Geelong Harbor Trust were responsible for the piers and wharves in their respective cities — they are now the government owned Port of Melbourne Corporation and the privately operated GeelongPort.