The US Geological Survey topographic maps are a useful tool for tracing limestone deposits. This information is necessary for determining karst terrains and areas with abundant springs that connect with underground channels.
All of the resources referred to in this article can be purchased from the USGS by calling 1-800-HELP-MAP, by sending an E-mail to infoservices@usgs.gov, or by using the Global Land Information System (GLIS) at http ://edcwww.cr.usgs.gov/webglis/. Each map costs $4, with a volume discount for teachers, plus a $3.50 handling fee per order. The prices of ot