These 50 index maps can be used as a quick reference
guide to choosing your 1:24,000 scale color USGS topographic 7.5
minute quadrangle from OMNI Resources.
These files are in PKZIP format and are quite large. Typically they
range from 4 to 8 megabytes. The number following the name is the
approximate size of the zipped file in Megabytes. Download times will typically be 30-45 minutes. Once you have downloaded them to your
computer, you must unzip them using PKUNZIP or other compression software. The resultant uncompressed files will be 5-13 Mb in size.
Each file contains a .tif file which you must view using appropriate software, such as PhotoShop;
Netscape cannot handle the large file sizes.