Earth Sciences Stamps by Gottschalk + Ash  Canada 1972 _ Issued by the host country to commemorate four International Congresses: Geology, Geography, Cartography and Photogrammetry _ #canada #stamps #fritzgottschalk #stuartash #geology #geography #photogrammetry #cartography #pictogram #earth #congress #geological #collection #stamps #mintneverhinged #canadapost #ottawa #ontario gottschalkash_zurich