Betula birch leaf 86mm, McAbee Fossil shales are sediments of a extinct shallow lake when a warm temperate climate in the northern hemisphere prevailed. The fossil record shows that this was a time when palm trees grew as far north as Alaska. Many plant species have been described from the Tranquil shale, including more than deciduous and Conifer. Sassafras, katsura and Ginkgo, and a diversity of insects, fish, and even rare delicate feathers. The fossils record plants and trees, flora and fauna from an ancient prehistoric forest which lay close to mountains surrounding a large lake. The leaves, flowers, seeds and insects of the forest were transported by wind, rivers and streams into the lake, where they sank to the bottom, were covered by fine sediments and diatoms.
The fine sediments enabled fossilization by carbonization, preserving the specimens completely in some instances, making possible detailed comparisons of the fossils to our modern day flora and fauna. Many of the specimens recovered or discovered today have yet to be identified and named by science. This establishes the ancient forests of long ago were much more diverse than our modern forest today. From the fossil deposits paleobotanists determine the perimeters close to the lake were predominantly forested with established genus types as elm, birch, alder and beech trees in the higher elevations spruce. firs and pine trees persisted most of the types discovered in the fossil beds are still extant today.