Oman lies between latitudes 16° and 28° N, and longitudes 52° and 60° E. A vast gravel desert plain covers most of central Oman, with mountain ranges along the north (Al Hajar Mountains) and southeast coast (Qara or Dhofar Mountains), where the country's main cities are located: the capital city Muscat, Sohar and Sur in the north, and Salalah in the south. Oman's climate is hot and dry in the interior and humid along the coast. During past epochs, Oman was covered by ocean, as evidenced by the large numbers of fossilized shells found in areas of the desert away from the modern coastline.