To access the State Line area from Grand Junction Colorado you need to travel west on I-70 for approximetaly 22 miles until you come to the town of Mack Colorado. Turn right onto Exit 11 and right again onto US-50/US-6 and travel just over 1/2 a mile to the intersection of Highway 6&50. Turn left onto Highway 6&50 and travel west for about twelve miles. You will pass the 6&50 entrance to Rabbit Valley on your left and right before the parking area you will come to another access road that leads south to Rabbit Valley. The parking area is a little used spot just past the second access to Rabbit Valley and about two miles from the Utah state line. There is one road that leads off to the west of the parking area that you can explore if you have a vehivcle with clearance, otherwise you should park just off the main road.
This area has a large number of fossilized shells and snail type fossils. The best places to look are along the little ridge lines where you see rock outcroppings. If you walk around a little bit you will see pieces laying around that people have left. These will give you an idea of what to look for. Your best bet of finding nice specimens is to go out after a heavy rainstorm and look in the little washes and around.
There is enough material in this area to allow you to be picky on what you take. Be sure to bring plenty of water and bug spray, the temperatures can easily exceed 100deg in the summer months and the gnats can be quite annoying. Have fun and “Rock On”