Temagami Magnetic Anomaly
The Temagami Magnetic Anomaly, also called the Temagami Anomaly or the Wanapitei Anomaly, is a magnetic anomaly resulting from a large buried geologic structure in the Canadian Shield near Temagami, Ontario, Canada. It stretches from Lake Wanapitei in the west to Bear Island in Lake Temagami.
Source: Wikipedia — Temagami Magnetic Anomaly (CC BY-SA 4.0)