The Narrows is a water gap

Water gap

A water gap is an opening or notch which flowing water has carved through a mountain range. Water gaps often offer a practical route for road and rail transport to cross mountain ridges.- Geology :...

 where the Raystown Branch of the Juniata River

Raystown Branch Juniata River

The Raystown Branch Juniata River is the largest and longest tributary of the Juniata River in south-central Pennsylvania in the United States....

 passes through Evitts Mountain

Evitts Mountain

Evitts Mountain is a stratigraphic ridge in the Ridge and Valley region of the Appalachian Mountains, located in Bedford County, Pennsylvania and Allegany County, Maryland-Geography:...

 in Bedford County, Pennsylvania

Bedford County, Pennsylvania

Bedford County is a county located in the U.S. state of Pennsylvania. As of the 2010 census, the population was 49,762. The county seat is Bedford. It is part of the Altoona, Pennsylvania, Metropolitan Statistical Area.- History :...

. Both U.S. Route 30

U.S. Route 30 in Pennsylvania

In the U.S. state of Pennsylvania, U.S. Route 30 runs east–west across the southern part of the state, passing through Pittsburgh and Philadelphia on its way from the West Virginia state line east to the Benjamin Franklin Bridge over the Delaware River into New Jersey...

 (part of the Lincoln Highway

Lincoln Highway

The Lincoln Highway was the first road across the United States of America.Conceived and promoted by entrepreneur Carl G. Fisher, the Lincoln Highway spanned coast-to-coast from Times Square in New York City to Lincoln Park in San Francisco, originally through 13 states: New York, New Jersey,...

) and the Pennsylvania Turnpike

Pennsylvania Turnpike

The Pennsylvania Turnpike is a toll highway system operated by the Pennsylvania Turnpike Commission in the Commonwealth of Pennsylvania, United States. The three sections of the turnpike system total . The main section extends from Ohio to New Jersey and is long...

 pass through the gap. It is located in the townships

Civil township

A civil township is a widely used unit of local government in the United States, subordinate to, and geographic divisions of, a county. Specific responsibilities and the degree of autonomy vary based on each state. Civil townships are distinct from survey townships, but in states that have both,...

 of Snake Spring and Bedford.

Geology

A major group of east-west trending faults and the erosional force of the Raystown Branch of the Juniata River

Raystown Branch Juniata River

The Raystown Branch Juniata River is the largest and longest tributary of the Juniata River in south-central Pennsylvania in the United States....

 are responsible for the existence of this water gap

Water gap

A water gap is an opening or notch which flowing water has carved through a mountain range. Water gaps often offer a practical route for road and rail transport to cross mountain ridges.- Geology :...

. Four formations are exposed on the north side of the gap (along a roadcut for the Turnpike): The Tuscarora

Tuscarora Formation

The Silurian Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia.-Description:...

, the Juniata

Juniata Formation

The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.-Description:The Juniata is...

, the Bald Eagle

Bald Eagle Formation

The Ordovician Bald Eagle Formation is a mapped bedrock unit in central Pennsylvania, USA. It is a ridge-forming unit in the Appalachian Mountains.-Description:...

, and the Reedsville Formation

Reedsville Formation

The Ordovician Reedsville Formation is a mapped surficial bedrock unit in Pennsylvania, Maryland, Virginia, West Virginia, and Tennessee, that extends into the subsurface of Ohio. This rock is a slope-former adjacent to the prominent ridge-forming Bald Eagle sandstone unit in the Appalachian...

. The Tuscarora is exposed on the south side of the gap along Rt. 30.