I've downloaded some USGS DEMs from the National Map, which appear to be .adf files. I can open them in ArcMap 10.2, but I need to merge them into a single mosaic. To do this, I've created a raster catalogue inside a geodatabase file, but when I try to 'Load rasters from workspace', the files are not visible.
Not sure what to do next. The files are clearly Esri-compatible (I can load and view them individually), but the steps to create a mosaic seem unable to read the files.