elevations near the highest peaks in the range. Some of the rocks in the park are the oldest found in any American national park and have been dated at nearly 2.7 billion years. Grand Teton National Park is an almost pristine ecosystem and the same species of flora and fauna that have existed since prehistoric times can still be found there. More than 1,000 species of vascular plants, dozens of species of mammals, 300 species of birds, more than a dozen fish species, and a few species of reptiles and amphibians inhabit the park. Due to various changes in the ecosystem, some of them human-induced, efforts have been made to provide enhanced protection to some species of native fish and the increasingly threatened whitebark pine. Grand Teton National Park is a popular destination for mountaineering, hiking, fishing, and other forms of recreation. There are more than 1,000 drive-in campsites and over of hiking trails that provide access to backcountry camping areas. Noted for world-renowned trout fishing, the park is one of the few places to catch Snake River fine-spotted cutthroat trout. Grand Teton has several National Park Service–run visitor centers and privately operated concessions for motels, lodges, gas stations, and marinas. Human history Paleo-Indians and Native Americans Paleo-Indian presence in what is now Grand Teton National Park dates back more than 11,000 years. Jackson Hole valley climate at that time was colder and more alpine than the semi-arid climate found today, and the first humans were migratory hunter-gatherers spending summer months in Jackson Hole and wintering in the valleys west of the Teton Range. Along the shores of Jackson Lake, fire pits, tools, and what are thought to have been fishing weights have been discovered. One of the tools found is of a type associated with the Clovis culture, and tools from this cultural period date back at least 11,500 years. Some of the tools are made of obsidian which chemical analysis indicates came from sources near present-day Teton Pass, south of Grand Teton National Park. Though obsidian was also available north of Jackson Hole, virtually all the obsidian spear points found are from a source to the south, indicating that the main seasonal migratory route for the Paleo-Indian was from this direction. Elk, which winter on the National Elk Refuge at the southern end of Jackson Hole and northwest into higher altitudes during spring and summer, follow a similar