terracing is an operator that is applied to potential field data to produce regions of constant field amplitude that are separated by sharp boundaries. magnetic data are usually transformed into pseudo-gravity data (baranov, 1957) prior to the application of terracing. the objective of terracing is ‘to recast potential field maps into a geologic map like format’ (cordell and mccafferty 1989). t...

Canada We would like to thank Statistics Canada for permitting access to the data and solving associated technical problems and Peter Schnabl for excellent research assistance. The authors take sole responsibility for errors, omissions and interpretation of the data. Contact: [email protected].

1 Department of Physics, University of California Berkeley, Berkeley, CA 94720-7300, USA 2 Department of Physics, Princeton University, Princeton, NJ 08544, USA 3 Department of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA 4 Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA 5 Laboratoire de Physico-Chimie Théorique CNRS/UMR 7083, ESP...