This map of the first vertical derivative of the magnetic field was derived from data acquired during an aeromagnetic survey carried out by Goldak Airborne Surveys during the period of May 16 to July 1, 2009. The data were recorded using a split-beam cesium vapour magnetometer mounted in the tail boom of a Piper Navajo aircraft. The nominal traverse and control line spacings were 400 m and 2400 m, respectively, and the aircraft flew at a nominal terrain clearance of 150 m.