The USGS Small Scale Shaded Relief from The National Map is a cached tile service that contains shaded relief elevation layers derived from the GTOPO30 dataset. GTOPO30 is a global digital elevation model with a horizontal grid spacing of 30 arc-seconds (approximately 1 kilometer). Small scale shaded relief represents data from GTOPO30 as if it were a surface illuminated by a light source 45 degrees above the northwest horizon. Small scale shaded relief can be viewed from the world scale to 1:9.2M in The National Map viewer. Go to http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30_info for more information on GTOPO30.