From the Google Earth Library, the site is now making available USGS topo (quads) for use in Google earth. From the site… “hese maps are intended to provide a free alternative to expensive commercial products that often cost $80 or more per state or charge monthly access fees. Plus you get the benefit of using the topo maps with Google Earth. The Topo maps are saved as individual KMZ files which must be downloaded in their entirety before they will be visible in Google Earth.” See HERE