Blue Mountain Ridge

Blue Mountain
Kittatinny Mountain (and nine others:  • Blue Hills,  • Kau-ta-tin-chunk,  • Kekaghtenemin Mountain  • Kightotinning Mountain,  • Kittachtinny Hills,  • Kittatinhy Mountain,  • Kittochtinny Hills,  • Kittochtinny Mountains,  • North Mountain)
The "Great Wall" of Blue Mountain
Highest point
Peak	Clarks Knob 2,320 feet (710 m)
Elevation	1,129 ft (344 m)
Coordinates	40°07′28″N 77°39′59″W / 40.12444°N 77.66639°W / 40.12444; -77.66639Coordinates: 40°07′28″N 77°39′59″W / 40.12444°N 77.66639°W / 40.12444; -77.66639
Dimensions
Length	150 mi (240 km) northeast-southwest to SSW 150 miles (240 km) (direct aerial) 255 miles (410 km) trace of ridgeline, including loops back width = varies along chain's length
Geography
Country	United States
State	Pennsylvania
Borders on	Ridge-and-Valley Appalachians and Great Appalachian Valley
Geology
Orogeny	Appalachian Mountains
Age of rock	Silurian
Type of rock	Tuscarora Formation and Shawangunk Formation; sedimentary

Blue Mountain Ridge, Blue Mountain, or the Blue Mountains of Pennsylvania is part of the geophysical makeup of the Ridge-and-Valley Appalachians in the U.S. state of Pennsylvania. It is a ridge that forms the southern and eastern edge of the Appalachian mountain range spanning over 255 miles (410 km) from the Delaware Water Gap as it cuts across the eastern half of the state on a slight diagonal from New Jersey tending southerly until it turns southerly curving into Maryland, and beyond.

Some distant view of The Blue Mountain dominates the southern tier of most eastern and central Pennsylvanian counties providing an ever visible backdrop cutting across the northern or western horizon. Most transport corridors and road beds piercing the barrier necessarily descend through either large water gaps (West to east: Susquehanna, Schuylkill, Lehigh and Delaware River valleys) or wind gaps their smaller tributary gaps cut by creeks, brooks, and lesser rivers. The descent into the southern lowlands are ramplike and before southbound travelers oft lays a scenic panorama spread from horizon to horizon. The barrier ridge forms a distinct boundary between a number of Pennsylvania's geographical and cultural regions.

To the north of the Susquehanna Gap in the south-central part of the state are the Cumberland Valley tucked in the area above the water gap as if trying to flow through with the river; to its northwest side are the southern reaches of the Susquehanna Valley with picturesque streams channeling travel corridors deep into and over the central and western mountains and valleys — the heartland interior counties of Pennsylvania; along the Main Branch Susquehanna, the valleys also lead into northeast Pennsylvania, into the "Northern Coal Region," of the Wyoming Valley and the distant Poconos. To the Blue Mountain Ridge's center, on the southern side lies the "capital region," about Harrisburg and nearby communities, the rich farming country of the Lebanon Valley, and Pennsylvania Dutch Country of York and Lancaster Counties, the lower half of the Lehigh Valley and the lower Delaware Valley; the latter two extend through water gaps beyond the ridgeline.