Do some testing before you shoot at f/38.

Adams was shooting with a view camera, with much longer lenses than your 18-55 zoom. (A 210mm lens is the "normal" focal length for a 4x5 camera.) The very small apertures were required for depth of field.

With a digital SLR camera, your "normal" focal length is about 28mm. To gain similar depth of field, F/8 or f/11 should be plenty. The major issue you face is Diffraction, which is caused by the very small aperture and which actually makes your photos less sharp. (The 4x5 camera at f/64 still has a very large physical aperture -- the actual size of the iris -- compared to your 18-55 at f/38.)

See this page this page for more information (and note that he was using a medium format camera, which will show less of this effect than your DSLR.) Also see this page for even more info.

Not what you wanted, I know. But realize that you can get that look using wider apertures because you are shooting with a smaller format camera. (And then realize that much of the Adams "look" comes from shooting large format film, developing using the Zone System, and hand printing everything.)