How to get there-- Drive southwest on RM 2323 from Llano. Keep driving, it's a ways, around 18 miles. It's 5.2 miles past Llano Co. Rd. 111. At this point you've driven all the way across the Enchanted Rock pluton and out the other side. The roadcut to look at is on an uphill grade with exposures on both sides, clearly sandstone on top of granite.
What to see: Roadcut shows Cambrian Hickory Sandstone unconformably overlying what appears to be deeply weathered Town Mountain granite. The granite is weathered, and channels were cut into the top of the granite and filled in with Hickory Sandstone. The channels are asymmetric, with one very step side, and sediment infilling has occurred from the shallow side toward the steep side. I'm not a sedimentologist, but it looks like a cut wall/point bar system to me. In the channel, there is a large cobble of granite contained in the sediment, it just above and to the right of the compass case in the image. Note the faint right-dipping bedding in the center of the channel.