In 1823, John Oxley, a British explorer, sailed north from what is now Sydney to scout possible penal colony sites in Gladstone (then Port Curtis) and Moreton Bay. At Moreton Bay, he found the Brisbane River. He returned in 1824 and established a penal settlement at what is now Redcliffe. The settlement, initially known as Edenglassie, was then transferred to the current location of the Brisbane city centre. Edmund Lockyer discovered outcrops of coal along the banks of the upper Brisbane River in 1825. In 1839 transportation of convicts was ceased, culminating in the closure of the Brisbane penal settlement. In 1842 free settlement, which had already commenced, was officially permitted. In 1847, the Port of Maryborough was opened as a wool port. While most early immigrants came from New South Wales, the first free immigrant ship to arrive in Moreton Bay from Europe was the "Artemisia", in 1848. In 1857, Queensland's first lighthouse was built at Cape Moreton.