Examples of chunked terrains can be found in the samples folder, and in the carlevel folder. Look for ".hmp" files. There are also lots of chunked terrains in user levels all over this forum, and in the user demos on the AU resource page.

If you have multiple heightmaps, you have the choice to create multiple chunked terrains from them, or use a paint program to merge them to a single height image. Both ways are equivalent.

Creating terrains from height maps is described in the MED manual.