The crustal thickness and P velocities in the Port Arthur, Ontario region of the Canadian Shield have been previously determined by seismic refraction techniques during the Lake Superior Experiment and Project Early Rise. In this study, the P phases of eleven teleseismic earthquakes recorded near Port Arthur have been studied by computing azimuths, angles of incidence, and spectral ratios to ascertain some crustal properties and compare these values with the refraction results. A P velocity at the surface of 6.1 ± .8 km/sec and a crustal thickness of 40 ± 5 km determined from the earthquakes are similar to but less precise than the refraction estimates of 6.3 km/sec and 38 km respectively. Transverse motions generated by the earthquake signal passing through the crust were observed and contributed to the uncertainty. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate