During the Carboniferous period (359–299 Ma), Scotland lay close to the equator. Several changes in sea level occurred and the coal deposits of Lanarkshire and West Lothian and limestones of Fife and Dunbar date from this time. There are oil shales near Bathgate around which the 19th-century oil-processing industry developed, and elsewhere in the Midland Valley there are ironstones and fire clay deposits that had significance in the early Industrial Revolution. Fossil Grove in Victoria Park, Glasgow contains the preserved remains of a Carboniferous forest. More volcanic activity formed Arthur's Seat and the Salisbury Crags in Edinburgh and the nearby Bathgate Hills.