and a nine-projector multi-image slide show. The show is approximately 14 minutes long and shares the story of logging from past until today. Programs and special events are offered throughout the year. The state park includes a campground, day-use area, and network of four-season trails for summer hiking and winter cross-country skiing. The Old Growth Forest Trail to the pine grove is a loop long. The Old Growth Forest is an even-aged stand of pines estimated to be between 350 and 375 years old. The tallest trees are between 150 and 160 feet tall, and have a girth of more than four feet DBH (Diameter at breast height). These eastern white pine are some of the largest trees in the eastern United States. The last remaining virgin maple and beech hardwood forest in the state is at Warren Woods State Park. There are two foot trails on the south side of M-93. The wooded Au Sable River foot trail is approximately three miles in length and takes hikers across the East Branch at two different locations. The Mertz Grade Trail winds through forest and field for approximately two miles and was named for the early logging railroad spur it shares for a portion of its distance. There are four small lakes located within the state park. Two of the lakes were originally named Bright and Star Lake. However, there were too many Star Lakes so they settled on Bright and Glory Lake. In the news Although changes in drilling technology make drilling for oil and gas possible under historically nonproductive strata in northern Michigan, including sections of state forests, the state of Michigan decided in 2014 not to auction off mineral rights under Hartwick Pines. See also Edward E. Hartwick Memorial Building: a structure within the park. References External links Hartwick Pines State Park Michigan Department of Natural Resources Hartwick Pines State Park Map Michigan Department of Natural Resources State parks of Michigan Protected areas of Crawford County, Michigan Protected areas established in 1927 1927 establishments in Michigan IUCN Category V Old-growth forests Civilian Conservation Corps in Michigan Forestry museums in the United States Industry museums in Michigan