Anyone that is moving from Source to UDK will find out that not having Source's displacements available to you make creating caves near impossible. This will help you make your own assets for caves.
Tutorial that covers how to create assets to be used in UDK for a cave. In this tutorial I create the entrance to a cave using 3DS Max and Mudbox, then baking the hi resoultion mesh onto a low poly mesh, then creating the texture to be used on it.
This can be used for UDK, Source, Crytek, Unity, etc.
Enjoy!