Petrified Forest of the Black Hills

For an adventure into the prehistoric past, your family will fascinated by the Petrified Forest of the Black Hills. Together, you'll discover ancient trees of stone and prehistoric fossils on a five-block walk through of the area. The stone logs vary from 5-100 feet in length and 3-5 feet in diameter, while the stumps range from 3-5 feet in height. On the self-guided tour, you and your family can let your imaginations run wild and pretend to be the dinosaurs that once roamed the area. For those of you who prefer facts and data, you can check out the rock, fossil, and mineral museum, which includes an interpretive film on the geology of the Black Hills, as well as digital and graphic displays.

The word, petrify, means to turn to stone. Petrified wood are trees that have been preserved and turned to stone by chemical and physical processes over the years. Scientists are not certain as to how petrification occurs because they have not been able to duplicate the process in the laboratory where observations can be measured and calculated. What they do know, is that oxygen had to have been kept away from the plant matter so that the tree didn't start decomposing.

This could have happened if trees fell in water and were then covered in sediment. Most scientists agree that most of the fossilized wood that is found today are found in ancient river beds of flood plains.

After a tree is quickly buried under water, it can either deteriorate, turn to coal, or become petrified. In order for it to become petrified, minerals from the percolating water must be deposited in fluid-filled openings and holes in the wood, which preserves the plant tissue. This process is known as permineralization. The last ingredient need to complete the petrification process is time.

Most of the petrified wood found in South Dakota date back 38 million years to 130 million years. There are several petrified wood deposits in South Dakota, all representing a different era in ancient history.

To get to the Petrified Forest of the Black Hills, take exit 46 off I-90 in Piedmont, South Dakota. It is located at 8228 Elk Creek Road.