Selectively merging DEMs

Discussion created by james.douglas103 on Jan 14, 2014
I have 2 DEMs of the same region, but from different years, that I would like to use as model inputs.
However, one of the DEMs is a different size to the other (both are 25m resolution but on is 237 columns by 201 rows and the other is 281 x 241).
My questions is can I merge the two so that they are identical dimensions to the larger of the two DEMs (required by the model) but still maintain the details of the different years? I am interested in what is happening in the middle of each DEM, thus the changes in the edges is not important.
Really, what I am trying to do is to use the surplus of the larger DEM to provide a border for the smaller DEM simply so their dimensions match.

Thanks for any help!