The first American inhabitants migrated into this area as the last glaciers receded 12,000 to 18,000 years ago. By the mid-18th century, Europeans arrived and initially settled near Wilkes-Barre, PA. These later settlers were mainly farmers from Connecticut who cleared the heavily forested lands in the Susquehanna River Valley using lumber for homes, buildings, and fencing. Europeans began mining anthracite coal in the late eighteenth century and by 1870 the region had over 200 collieries that produced over 14 million tons of coal. By 1914 the mining industry reached its peak employment of 180,899 and by 1917 the annual amount of coal mined reached to 100 million tons. The rapid growth of regional mining and urban settlement significantly changed natural and historic land use patterns. Large tracts of timber were cleared to open land for new mine, industrial, and urban development. Lumber use grew dramatically for anthracite breakers, surface buildings, mining towns, urban markets, and to shore up mine shafts and underground workings. Waste material from coal mining, called culm, was piled on the landscape near mines creating new land forms called culm banks while thousands of miles of mine workings and rail road corridors were cut to mine and transport coal to new markets. As earth-moving technology advanced from the late 19th century, mines used large excavators and trucks to strip away the various layers of earth, called overburden, to reach coal seams leaving behind large piles of waste and deep open pits.