Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Vulcan structure is a 350 kilometer (217 mile) long major convergent boundary between the Medicine Hat Block and the Loverna Block, Archean basement rock structures which lie between the Wyoming craton and Hearne craton on the western edge of the North American craton.It lies under the Western Canadian Sedimentary Basin.The Vulcan structure has intrigued geologists because it is a region of low gravity and contains an east-trending magnetic anomaly which cuts across the magnetic field of southern Alberta at a high angle.