volcanism in the volcanic zone. Further evidence for continental rifting in the Northern Cordilleran Volcanic Province is magmas are mainly alkaline, it includes highly alkaline and peralkaline rock types, the main spatial-temporal pattern of volcanism is in the middle of the volcanic province followed by movement to the south, north and possibly northeast, heat flow in the Northern Cordilleran Volcanic Province is high, seismic activity is largely absent in the volcanic province and the largest period of volcanism correlates with an interval of net extension between the Pacific and North American plates. A range of more heavily alkaline rock types not commonly found in the Western Cordillera are regionally widespread in the Northern Cordilleran Volcanic Province. These include nephelinite, basanite and peralkaline phonolite, trachyte, and comendite lavas. The most magnesium oxide-rich nephelinites, basanites and alkaline basalts all through the Northern Cordilleran Volcanic Province display trace element abundances and isotopic compositions that are logical with an asthenospheric source like those for average oceanic island basalt and for alkaline basalts younger than five million years in the rift-related Basin and Range Province of southwestern United States and northwestern Mexico. One hypothesized explanation for oceanic island basalt in the Earth's upper mantle under the Northern Cordilleran Volcanic Province is the existence of a slab window. However, not much of a noticeable evidence linking the production of magma in the upper mantle to a possible tectonic system has been stated. The existence of a fault next to the western flank of the Mount Edziza volcanic complex is normally considered to be the prime structural evidence for continental rifting in the Northern Cordilleran Volcanic Province. However, more recent mapping and seismic studies in the Coast Mountains have documented the presence of brittle rift-related faults southwest of the small community of Stewart in northwestern British Columbia. But these faults were in a matter of dispute in 1997 by geologists, stating these faults were last active between 20 and five million years ago. In 1999, a sequence of north-trending faults were mapped that seem to represent young rifting events parallel with the southwestern boundary of the Northern Cordilleran Volcanic Province. These rift-related faults might have been active as recently as five million years ago and they might have connections with adjacent Miocene and younger volcanic activity in the southern part of the Northern Cordilleran Volcanic Province. In addition, brittle faults with similar north-trending directions might enlarge as