High Quality Content by WIKIPEDIA articles! The Ottawa-Bonnechere Graben (also known as the Ottawa Graben), with its branch the Timiskaming Graben, is an ancient rift valley in the Canadian Shield of Northeastern Ontario and Quebec, Canada. This rift valley was formed when the Earth`s crust moved downward about a kilometre between two major fault zones known as the Mattawa and Petawawa faults. These ancient faults are still active and occasionally release stress in the form of earthquakes, such as the 1935 Timiskaming earthquake and the 2000 Kipawa earthquake. The length of the graben is about 700 km (435 mi).