Three miles of the Meramec River flow through Shaw Nature Reserve. Geologically, the Meramec, like other Ozark rivers, is classified as an entrenched meander and has been downcutting through the ancient Ozark rocks since the last uplift about 1 million years ago. This downcutting produced the spectacular bluffs and steep hills and valleys in the southern half of Shaw Nature Reserve. The gradient of the river through Shaw Nature Reserve is gentle enough for pleasant canoeing with stretches of faster water to make it interesting.
The Meramec is host to a great variety of fish, turtles, and freshwater mussels. Green herons, great blue herons, and bank swallows are often seen by hikers and canoeists along the river. Muskrats and beavers live here and their tracks and those of raccoon and deer are common in the mud along the river.
Several large gravel bars are located on the three-mile stretch of the Meramec River which flows through Shaw Nature Reserve. The shape and size of these gravel bars are constantly changed by the powerful force of flood waters. Annual plants and trees spring up from seeds left by the receding water. Their roots stabilize the new deposits of silt and gravel. Later floods tear out most of the young sycamore and silver maple, but the deeper rooted willows hang on.
People of all ages enjoy exploring the gravel bars. Here is an endless variety of chert, sandstone, and limestone rocks, piles of driftwood, animal tracks, frogs by the hundreds, the sight and sound of swift, free-flowing, clear water.