RR: Forgotten Gabes: Jackson Loop

[GP_pilot]

I don’t believe mountain bikers take much interest in the geology that created terrain they ride. Sure the world renown Moab Slickrock was created from petrified sand dunes from the Jurassic Period (205-140 million years ago), but I never give a second thought to the terrain in Socal. What matters most is satisfying your riding fix whether on cross country, downhill or a combination of the two. It’s on your drive to the trailhead through Wrightwood and up to Big Pines, you can’t help but notice the two 7,000’ ridgelines on both sides creating the Swarthout Valley. Once reaching Big Pines and bearing right on to the Big Pines Highway, the road twists, turns, and folds back on itself as you descend down into the Antelope Valley high desert. Along the way, you’ll see some pretty dramatic features not cut by road crews. This entire section through the San Gabriel mountains runs along the infamous San Andreas Rift Zone. About 2 miles from the Big Pines turnoff, you’ll come to Jackson Lake on your left and an exposure of rock on the right. An example of two extremes. Jackson Lake is a sag pond, created when an area of earth drops between two parallel fault zones and water fills the depression. The rock on the north side of the road was crushed by movement along the fault and is similar to the whitish rock powder you’ll find other places in this locale. There's a few other points of interest of the San Andreas in the area, but it's easliy seen from satellite map imagery off Google Map.

The trailhead for this next ride is Jackson Lake.



The Jackson Loop route combines two trails, going from Jackson Lake at 6,100’ to Jackson Flat campground at 7,500’ and back. The first trail doesn’t have an official name, but starts out in the upper part of Grandview Canyon and somewhat parallels the Fenner Saddle Road below it. It’s finding the start of the trail which is the most challenging. Even consulting a topo map, it took me three attempts before I found the start of this trail and still got lost. The start is a confusing zig zag of service roads and trails. First, take back out the road that you just drove to the parking lot. Before reaching the Big Pines Hwy, a dirt service road starts on your left that you pickup. Almost immediately, there’s another road climbing to your back and to your left. Going straight at this point on 4N12 is Fenner Saddle Road. Barely 0.1 mi after climbing, there’s yet another service road on your right. This will bring you into a flat clearing and you’ll keep going straight out the other side on some double track. Shortly this fizzles into singletrack.



It will climb up around a knoll, past a log bench and finally bring you out to another but unused service road at 0.9 mi from the parking lot. It’s best to take a left here and continue for another 0.21 mi to the next junction.



(Note: If you do go right, it will this will all but end in half a mile at which point you’ll need to scramble 100’ up a ravine to get onto the singletrack.) At this junction, take a right on more double track. At 0.11 mi, you’ll hit two trailheads. Left is signed as the Jackson Lake Trail which you’ll come down.



Right is the unmarked, but well packed singletrack you’re picking up.



This has a consistent, gradual climb.









With one small washout section









About 2.4 mi later you’ll hit the end of the trail, putting you out at a 180 degree turnout on 3N26.2. Here you want to go left, heading up towards Jackson Flat.



There are no markings at 1.4 miles, but you’ll see a trail heading over an earthen berm on your left. If you want to continue to Jackson Flat campground, head another 0.5 mi up the forest road which eventually becomes paved. Signs for the campground will be evident on your left and up to the parking lot. You have an additional option of continuing to Grassy Hollow Visitor Center if you stay on the paved road for another 1.1 mi. At either place there’s bathrooms and water if you need them. Jackson Flat is a group campground by reservation only, so while there’s a pretty good chance it will be occupied on the weekends, during the week it’s likely to be vacant except for the campground manager’s motorcoach. If you so desire, there’s also a spiral observation platform about 300 yards up the hill from the east end of the parking lot.



Additionally, there’s two nature walk loops, one west and east sides that have fallen into a somewhat unmaintained state.

Back at the trailhead, you’ll almost immediately see another trail heading off to your left, paralleling the road. Although it’s not marked, this is the PCT. You’ll need to transition your bike however you so desire for 250’ to the next trail split. At this junction, you’ll see the sign for Jackson Lake Trail.



The next 1.3 miles will go by quickly as you descend 1,000’.









You’ll then hit the service road that you used coming up 0.11 mi just before turning right onto Grandview Trail. From here, you’ll stay left at all junctions all the way back to Jackson Lake. In this section you’ll actually see the lake below.



Near the very end, there’s a short cut to drop you back into the parking lot. The Jackson Lake Trail has evidence of heavy foot traffic, so pay attention for possible hikers especially on weekends and holidays. Another fun singletrack loop added to the books.




Status: Unknown – Little known (Locals & Hikers)
Distance: 7.2 mi (loop), 3.6 mi for Grandview Trail, 2.2 mi for Jackson Lake Trail
Total Descent: 2027’ (loop), 283’ for Grandview Trail, 1618’ for Jackson Lake Trail
Total Ascent: 2216’(loop), 1447’ for Grandview Trail, 128’ for Jackson Lake Trail

Ride reports in the Forgotten Gabes series:
Blue Ridge Trail – Forgotten Gabes: Blue Ridge Trail
Acorn Trail – Forgotten Gabes: Acorn Trail
Pinecone Trail – Forgotten Gabes: Pinecone Trail
Table Mountain Ridge – Forgotten Gabes: Table Mountain Ridge

[PacMan]

Another sweet write-up bro!!

[Evil Chocula]

Dude, you have mastered the art of the RR.

[dubjay]

Nice writeup! I noticed you have some sort of GPS on your bike. Any .gpx files that you can share?

[art23rockpile]

Yes! Another nice addition to your series.

Now i'm thinking that a camping trip up there would be the hot ticket... one could probably hit most/all of these rides in 2-4 days.

[project_d]

GP...that's an awesome RR!!! Thanks for the inspiration!

[DISCO]

I sigh when thinking about riders who never go out of Aliso, fully loop, or fire roads. These heavy sophisticated bikes we pilot were intended to slay mountains (not many dragons left these days) and this is exactly why I choose to participate in the forums here.

Splendid work my friend, I look forward to adding this notch to my belt shortly.

[GP_pilot]

Originally Posted by dubjay

Nice writeup! I noticed you have some sort of GPS on your bike. Any .gpx files that you can share?

Yes I use an Edge 305, but these reports sometimes take 2 rides to put together along w/ dead ends and other non relative routes. Basically I write up the best route, thus my .gpx files wouldn't make sense. Just print off a free topo map (www.digital-topo-maps.com/) and use my writeup to supplement. Enjoy.

[JoeTruth]

Wow, that's awesome! You just gave me a nice flashback to the mid to late 70's. I used to attend a community camp on the north side of the highway, over looking Jackson Lake. Back in the day, we even used to swim in the swampy water. I've camped @ Jackson Lake in the winter when the lake was completely frozen over and somehow, one of my cousins managed to still fall in. Luckily, we got him out pretty quickly. I've hiked that trail but only up a couple of miles and back. Beautiful high country with tall pines all around. I'm enjoying your 'Forgotten Gabes" series, a lot! I think you've kindled an interest to ride the area for many riders here. Job well done and objective met! Thanks for taking the time to post another great RR.

[airgabe]

The best documentation of any RR ever.....Thanks for your accuracy and scientific knowledge... You inspire many of use to explore our physical and mental limits.

[dstepper]

With Highway 2 closed us on the West side of the San Gabs just don't get over there much. Because my sister lives near Wrightwood I have been on many of those trails but not for 3-4 years. My problem with the area is that the legal singletracks are not very long and to get a decent ride in I was linking Jackson Lake Trail system with Blue Ridge. I am so hoping that you can figure out some better routes than I did.

On another note, I keep looking down into Cabins Flats from Guffy Campground and to this point have not dropped down there. It sure looks like a bitch to get back out of.

Dean

[MTBMaven]

Just stumbled upon the Forgotten Gabes series. Great stuff. Thanks!

Regarding the geology of Jackson Lake. If I could add that the lake was formed when the movement of the San Andreas cut off the existing drainage, which in turn formed a lake. This is different than the Lost Lake sag pond near the 15 at Cleghorn, which was formed due to subsidence as a result of ground up earth as the North American and Pacific plates slide past each other along the strike slip edge of the San Andreas Fault.

I looked back at my notes from one of my college geology classes where we took at field trip tracing the San Andreas from the 15 to the 14. My notes indicate there is no official name for the type of formation that caused Jackson Lake. I always thought it would be great to see it names after my professor, a Stoutified Lake formation for Dorothy Stout PhD. She died several years ago of a brain tumor. I owe much of my career to the inspiration and joy of learning she in parted upon me.