These two trails are actually part of the James River Park system, and are totally flat with no hills, no gullies, no log crossings, etc... and run parallel with the scenic James River:
HUGUENOT TRAIL --- This is a very short, very muddy (especially after it rains), singletrack trail through the woods. It does have a few wood bridge crossings, but nothing really exciting. It's a place to go play around and get wet and muddy. Huguenot Trail will come out onto Riverside Drive, and from there you can follow the James River and ride on the blacktop (Riverside Drive) down to the Pony Pasture.
PONY PASTURE --- This is a doubletrack loop from the main parking lot. It is all rough gravel and crushed stone and, like Huguenot Trail, it is totally flat, but does have a few muddy sections and wet sand sections. There are no wood bridge crossings, log jumps, ravines, etc... It does have a few hidden single track sections here and there that connect up through the woods.
On weekends, it is best to avoid the area due to crowds - especially in the summertime. But it is a nice local place to practice speed and traction control in the mud. Some may say that the area is completely lame, which I kind of agree, but still, it is a good place to goof around and get muddy.