If with "mounds", you mean a kind of terrain spikes, the problem is caused because you have set your Mesh resolution too high, instead of using the 5 meters/pixel setting suggested in the KIAH manual, Page 10.
Setting the mesh any higher than that is useless, because no meshes with a *real* (not upsampled) resolution higher than that exists, and if you make the sim upsample the mesh for you (by setting a value higher than necessary), it will cause those visual artifacts and will use more system resources for no real benefit.