A large bur oak tree in the draw began growing in 1717, according to a sample taken by a State Forester, making it more than 289 years old. The United States did not become a country until 1776. One oak tree in the park is nearly 400 years old. Hackberry trees to the right have distinctive bark patterns and produce small hard berries that readily become fossilized, showing that they have lived in SD for at least 22 million years. Although they have accumulated parasites, they have evolved the ability to cope with them.