Blue Cut

General Information
Other Web Information

General Information

Blue Cut (2,602') is the name of a road cut through blue-gray colored rock, the Pelona schist on Historic Route 66, Cajon Boulevard.

Lots of lines go through, or are cut through, here: Cajon Creek, San Andreas Fault, railroads, highways, pipelines, powerlines.

What stories this small spot could tell! Stories of fires and of earthquakes, stories of cars and trains, stories of travelers coming and going, stories in rocks and in routes. Its narrowness concentrates social and geologic history in this one small place.

You could say this is where the San Gabriel Mountains end and the San Bernardino Mountains begin.

"Cajon Creek separates the San Gabriel and the San Bernardino mountains...As Cajon Creek canyon penetrates the mountains, it becomes narrower and deeper, and Interstate 15 rises onto its northeast wall. The San Andreas fault lies a scant mile or two to the northeast, on a bearing that gradually converges with the highway. About three miles beyond Devore, the highway curves broadly to the northeast, and enters the first of two deep, double-walled roadcuts. Much of the rock in these and some of the preceding roadside cuts is laminated, dark gray Pelona schist. It is a major part of the rock terrane southwest of the San Andreas fault. The rock in the last cut is dark and slightly greenish, and much broken by the stress and strain of being alongside the San Andreas fault, possibly for millions of years." From page 92, Vignette 11, The San Andreas Fault and Cajon Creek Cooperate, Cajon Pass, San Bernardino County, Geology Underfoot in Southern California, Robert P. Sharp and Allen F. Glazner.

This, then, is the Blue Cut. There is a large chain link fence that protects the road from the falling rocks. The color of the rocks changes with the direction you approach the cut and with the time of day.

(CalTrans also calls one of turnouts on Angeles Crest Highway "Blue Cut", which is another cut through the Pelona Schist farther west. It is between Grassy Hollow and Vincent Gap at mile marker LA 76.11.)


Maps: Road map from Yahoo!; topographical map from TopoZone (Blue Cut is at the four red dots), USGS 7.5' map Cajon Quadrangle, latitude 34.263ºN, longitude 117.466ºW; UTM 11 457088E 3791253N

By Car: You can drive Historic Route 66, signed Cajon Boulevard, from Cleghorn to Kenwood right before the 215 split. You can see the cut better on this road.

From Interstate 215 northbound, take the Kenwood exit which is immediately after the junction with the I-15. Turn left, go under the freeway and turn right.

From Insterstate 15 northbound, it is better to take the Cleghorn exit unless you are able to move very quickly to the right and get off at Kenwood. From the Cleghorn exit, turn left, go under the freeway, and turn right.

From Interstate 15 southbound, take Cleghorn exit, turn left.

Other Web Information

The Rocks: displacement of the Pelona schist and local alluvial deposits along the San Andreas Fault in this location has significantly aided the study of earthquakes

The Roads: variously named National Old Trails Highway, US Route 66, US Route 395, Interstate 15, Cajon Boulevard, or Historic Route 66

The Trains: two train tracks, a northbound and a southbound. Railfanning, a popular hobby here, has produced many web pages with pictures.

The Fire

Go to Field Guide to the San Gabriel Mountains: Places

Copyright © 2002 by Jane Strong and Tom Chester
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Jane Strong | Tom Chester
Updated 9 November 2002.