Larval fossils are often found in limestone.
Fossils form over thousands of years on the crust of the earth. Sand and other elements bury plants and organisms under layers and layers of mud and calcify them into stone. A rock's composition and geographic location give clues to the age and identity of the fossils it contains. A fossil, by definition, is at least 10,000 years old. Some may be millions or even billions of years old, since the earth itself has been around for nearly five billion years.
Coquina
Coquina-filled beaches surround the Ancient City of St. Augustine, Florida,
Tiny coquina shells found along the coasts of California and Florida form into beds of fossil rock also known as brittlestar. Examples of coquina limestone known as ophiuroid are on display at the Peabody Museum of Natural History at Yale University and the Florida State Museum. The Peabody also has abundant examples of Miocene brittlestar coquina fossil from the Santa Margarita Formation in California. Miocene fossils are between 5 and 25 million years old.
Limestone
Fossilized leaves
Limestone is the most common fossil rock. The state of Oklahoma has large deposits of limestone fossils, especially in the eastern and southern parts. Rather than being formed with shells, as it is along the coasts, Oklahoma's limestone has primarily plant fossils. Some of the most famous animal fossils found in limestone are from the Jurassic period 150 to 200 million years ago, when England was under water, along with much of Western Europe, especially Germany and Switzerland. Jurassic limestone has also been found in Israel.
Sandstone/Siltstone
The state of Kansas is loaded with gastropods fossilized over millions of years.
Fossils in sandstone are miracles of time, wind, and water, most often deposited from lakes and rivers. Sandstone in South Dakota yields gastropods - shells such as snails and whelks - carried thousands of miles. Sandstone in Death Valley, California contains fossils from the bodies of horses, rodents, even tapirs and camels. Mississippian siltstone found as far north as Ohio bears marine fossils of sea creatures living at the bottom of the ocean 350 million years ago.
Shale
Pennsylvania shale forms beautiful waterfalls
Pennsylvania's coal fields are rich in shale containing over 80 different species of plant fossils. Texas shale is also full of fossils, as is Waldron shale found in Tennessee, near Nashville. The Marble Mountains of California's Mohave Desert have an area open to the public called the Trilobite Wilderness. Trilobites are hard-shelled, insect-like marine creatures, extinct for 300 million years. Look on the map for the Lower Cambrian Latham Shale to find these ancient fossils. In nearby Nevada, fossil-seekers can also find productive deposits of shale.
Volcanic Rock
Fossilized dinosaur bones
Lava from a volcano erupts, covering everything in its path. When the lava hardens into igneous rock, whatever is underneath it becomes fossilized over time. Sometimes whole trees are petrified. One of the most interesting volcanic fossils ever found is dinosaur dung, millions of years old.
Tags: million years, along coasts, fossil rock, fossilized over, found limestone
