General Information
Access
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.)
Access 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
- Pelona Schist, Wrightwood, California shows a picture of the rock along with a description
- 1812 Wrightwood Earthquake, 1899 Cajon Pass Earthquake, and 1970 Lytle Creek Earthquake
- Cajon Pass Region Virtual Field Trip shows a small geologic map, large images, and videos of the area
- Displacement of basement rocks by the San Andreas Fault states that "the distribution of the Pelona-type schist has played an important role in many attempts to measure the slip on the San Andreas fault in southern California."
- Description of the geology of the Devore 7.5' quadrangle details the "numerous active faults within the quadrangle, including right-lateral strike-slip faults of the San Andreas Fault system..."
- Regional Gravity Map, San Bernardino Basin, Southern California reports, "One of the biggest hurdles in understanding the history of movement along the San Andreas fault system is understanding which fault strands have been active at what times and how slip is transferred between fault strands. The faults between San Gorgonio Pass and the Mojave Desert comprise one of the more complex knots in the San Andreas fault system."
- Slip Rates "across active faults are important variables in calculations of earthquake probabilities"
The Roads: variously named National Old Trails Highway, US Route 66, US Route 395, Interstate 15, Cajon Boulevard, or Historic Route 66
- Cajon Pass & Mormon Rocks, history gives the first uses of the road, "For the first several decades of its use the Pass was known for the presence of marauding Utes, under Walkera, "Hawk of the Mountains" and for Anglo and Mexican horse thieves. The arrival of the Mormons and others helped stabilize the Cajon area which remained at the edge of civilization."
- Cajon Pass Coastal Gateway continues the tale, "In the early 1800's it [Cajon Pass] was the southern end of the Old Spanish Trail which led to Santa Fe, New Mexico."
- US 66, 91, 395 Photo Gallery Inland Empire and Cajon Pass tells us that, "The first [highway] was a precipitous toll road followed by the first paved highway, built by the state in 1916." Excellent road history with vintage photos.
- History of the US Highway System explains some of the name changes that occurred in California
- Cajon Pass and the Blue Cut, California states, "The Blue Cut was a cliff found above the old 20's alignment of Route 66. The road kept getting covered in talus as erosion brought down rocks. Finally a newer alignment was designed in the 30's. The stream had to be redirected to allow for the new road." A car tour with pictures of the way it looks today
- From the Digital Desert Roads & Trails in the Mojave Desert with many wonderful photo tours of the area
The Trains: two train tracks, a northbound and a southbound. Railfanning, a popular hobby here, has produced many web pages with pictures.
- This train picture of UP 4755 shows the color of Blue Cut very well
- The Railfan's Guide to Cajon Pass Part Two : Blue-Cut, Swarthout Canyon, and the Keenbrook Overlook, well-done description of what to see and how to get there
- Cajon Pass Blue Cut Pictures
- UP 3985 at Blue Cut, here the light is reflecting off the polished rock in the lower half of the picture
- SF 3751 enters the burn area of Cajon in Blue Cut, the burn has revealed more of the blue rocks
- Information on Cajon Pass and its history, pictures of how it looks today and of the trains that run thru it everyday, BNSF, ATSF Warbonnets, Union Pacific and Southern Pacific.
The Fire
- Blue Cut Fire Incident Information San Bernardino National Forest Narrative & Summary 6/20/02 Day
- Blue Cut/Louisiana Fire Closure Area 118K pdf map
- Blue Cut Fire, San Bernardino National Forest, 20 June 2002 As viewed by the FireMapper™ Thermal-Imaging Radiometer
- Earth Observatory Natural Hazards Bluecut Fire north of Los Angeles
- A Day at the Rails: The Cajon Pass Fire, June 18, 2002 pictures
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:
http://tchester.org/sgm/places/blue_cut.html
Comments and feedback: Jane Strong | Tom Chester
Updated 9 November 2002.
