https://www.geocaching.com/geocache/GCAAYM7_an-empty-30ka-sedimentary-intermoraine-basin
GCAAYM7 An empty... 30ka sedimentary intermoraine basin! (Earthcache) in Guarda, Portugal created...
Geocaching is a treasure hunting game where you use a GPS to hide and seek containers with other participants in the activity. Geocaching.com is the listing...