If you don't have access to ArcGIS, Google Earth (aerial photos + 3D topography) and a transparent 24k topographic map (standardized base) can provide a very serviceable base for geologic field maps. I use Adobe Illustrator to make my maps, so my linework, symbology, cartographic element, marginalia, etc. is all done there. There are a few tricks to get consistent results. Returning to the same scale can be a pain. Here's the way I do it. - Download the 1:24,000 scale USGS to