Southern Indiana's natural and human history began some 350 million years ago when Indiana, like most of the continental United States, was covered by a shallow, tropical, inland sea. Through the geologic ages, the sea evolved and retreated, leaving behind the siltstone, shale and limestone bedrock that today underlie the region's various landforms, from the rugged, forested uplands that dominate the Natural Bloomington tour area on the east to the gently rolling Karst topography on the west.
From the time humans appeared 12,000 years ago until the white man arrived in the mid-16th century, an estimated 87 percent of the state was forested. By the turn of the 20th century, roughly 100 years after the settlers arrived, Indiana led the nation in timber production, and the verdant hillsides that stretch from Bloomington south to the Ohio River were ecological disasters. The region's lush landscapes today are a consequence of nearly a century of careful public lands management, driven by steady public pressure.
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