Everglades National Park was established in 1947 to protect a most unique ecosystem notably the worlds largest marshland, the famed "river of grass". While the water appears to be still it is actually moving at a rate of nearly 100 feet per day. The depth varies from a few inches to several feet as it flows south toward Gulf of Florida. The careful observer will observe the saw-grass prairie with its stands of pine trees, shifting to cypress which will be replaced the mangroves as the water becomes more salty as it nears the Gulf. The land of the Everglades is some of the youngest land on earth, only appearing after the last great ice age some 7,000 years ago. The elevation of the park extends from sea level to a lofty 4-5 feet. Slight elevation gains give birth to areas called domes and hammocks where various trees (pine, gumbo limbo, mahogany and oaks) struggle to live.