Reflection profiles shot about 10 km north of the Edmonton seismic observatory (EDM) indicate dips within the crust of 15 to 20° southeast, with a prominent reflecting horizon at 20 km apparently being offset 4 km by a fault. The average velocity in the crust to this horizon is 6.3–6.4 km/s. Deeper reflections tentatively correlated with the "Riel" discontinuity mapped in southern Alberta indicate a velocity in a second layer of 6.5 km/s to a depth of 32 km, with the base of the crust being essentially horizontal at 35.5 km. The lowermost portion of the crust appears to be significantly thinner here than in southern Alberta, although the general features of the seismic records appear similar in both locations.Velocities are determined by a modified version of the velocity spectrum technique, which does not require common depth point data.

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