Yes it is marked.  I've never ridden it but it looks like it is just cut throughs off the main trail.

If you are looking for a shorter but fun loop you can ride the trail as marked, drop all the way down to the River on the first descent, climb the River climb and then you will begin descending again, when you get to the intersection to the "Valley Bridge" turn left, that cuts out the hardest part of the Gorge Climb.  You can then continue to follow the Green loop from there, or as you pass through the field and can see the gravel road cut through turn left and go back to the car.

Enjoy

Rode this for the first time yesterday. Allow me to say a few things: 

1. Great trail. Primitive and great. 
2. Some really fun, flowy sections and swooping downhills (except for the Big Plunge - with all the leaves and the steep angle of the drop I walked that, which probably was more dangerous than riding it. I know, I know. It can probably be ridden NP, but I was tired and psychologically beat up at that point). 
3. The climbs are painful and long, which is how I ended up tired and psychologically beat up. 

and finally, 

Thanks for all the hard work and sharing your land for the greater good. Probably won't become a regular part of my rotation because I live so far away, but I'll be back for another shot at the BP. 

Also - there was a flock of (no kidding) thirty or so wild turkeys running around. So, Steve-O, when is the "Turkey Shoot" loop coming (and by that I mean, when can I go out there with a 12 gauge and plate one of them up, for a modest fee)?

I ride RRT on a regular basis since it's the closest trail to the house. I wouldn't say any of the climbs are long, but yeah they defiantly hurt! The plunge and its little jump are easier done than looked at. 

My new ride is doing a combo of Green and regular trail. First lap is normal trail to the gorge climb then follow it around to the kick out back to the parking lot. 2nd loop is taking the first 2 green options then finishing out the trail as normal. 

As stated above you can make the trail about as long as you want by just cutting out but I find using the new shortcuts makes for a more fulfilling ride w/o "bailing" at least that is how it works in my head.