Blacklog Creek is a 28.5 miles (45.9 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of Aughwick Creek

Aughwick Creek

Aughwick Creek is a tributary of the Juniata River in Huntingdon County, Pennsylvania, in the United States.Aughwick Creek, born from the confluence of Little Aughwick Creek and Sideling Hill Creek near the community of Maddensville, joins the Juniata River a few miles below Mount...

 in Huntingdon County

Huntingdon County, Pennsylvania

Huntingdon County is a county located in the U.S. state of Pennsylvania. In 2010, its population was 45,913.Huntingdon County was created on September 20, 1787, from part of Bedford County. Its county seat is Huntingdon.-Geography:According to the U.S...

, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

It rises in the Tuscarora State Forest

Tuscarora State Forest

Tuscarora State Forest is a Pennsylvania state forest in Pennsylvania Bureau of Forestry District #3. The main office is located in Blain in Perry County, Pennsylvania in the United States....

 and flows southwestward between Blacklog Mountain to the northwest and Shade Mountain to the southeast, forming the Blacklog Valley. After a long run down the valley, it joins Shade Creek

Shade Creek

Shade Creek is a tributary of Stony Creek in Somerset County, Pennsylvania in the United States.Shade Creek, formed by the confluence of Dark Shade and Clear Shade creeks approximately 1.9 miles downstream of the community of Cairnbrook, flows for 9.5 miles to join Stony Creek at the...

 and turns west, carving the Blacklog Narrows through Blacklog Mountain. This gap carries U.S. Route 522

U.S. Route 522

U.S. Route 522 is a spur route of U.S. Route 22 in the eastern United States. The southern terminus of the route is at U.S. Route 60 in Powhatan, Virginia. The northern terminus is at U.S. Route 11 and U.S. Route 15 in Selinsgrove, Pennsylvania. US 522 passes through the states of Virginia, West...

 and the former grade of the narrow gauge East Broad Top Railroad

East Broad Top Railroad

The East Broad Top Railroad and Coal Company is a for-profit heritage railroad headquartered in Rockhill Furnace, Pennsylvania, north of Interstate 76 and south of U.S. Route 22, the William Penn Highway. The railroad operates excursion trains on a seasonal schedule.-History:The East Broad Top...

's Shade Gap Branch (now occupied by the Rockhill Trolley Museum

Rockhill Trolley Museum

The Rockhill Trolley Museum is located at 430 Meadow Street, Rockhill Furnace, Pennsylvania, north of the Pennsylvania Turnpike and south of US 22, the William Penn Highway....

's standard gauge Shade Gap Electric Railway), and was formerly the site of the Winchester and Rockhill iron furnaces. The Narrows was also the site of at least two iron ore mines during the 1870s. Blacklog Creek flows between Rockhill and Orbisonia

Orbisonia, Pennsylvania

Orbisonia is a borough in Huntingdon County, Pennsylvania, United States. The population was 425 at the 2000 census.-Geography:Orbisonia is located at ....

, cuts through Saddle Back Ridge and joins Aughwick Creek approximately two miles downstream of the two towns.