Abstract Outcrops in and near the settlements of Cache Creek and Ashcroft, southern British Columbia (Fig. 1), provide an opportunity to view some of the structures and rocks that help to explain the evolution and amalgamation of the allochthonous terranes of the southern Canadian Cordillera. Sediments and igneous rocks ofthe Cache Creek and Nicola Groups formed in late Paleozoic to late Triassic times in oceanic and island arc settings. The sediments of the Ashcroft Formation were deposited from Early through Middle Jurassic time in an arc-related basin. In Late Jurassic or possibly earliest Cretaceus time, thrust faulting juxtapose Cache Creek-Nicola rocks over Ashcroft strata. This event is thought to have sutured these terranes to Quesnellia of which the Ashcroft Formation is generally considered to be a part. This faulting may havebeen related to the early (Late Jurassic) deformationin the Omineca Crystalline Belt when east-directed thrust faults joined Quesnellia to that crystalline terrane.

Abstract Outcrops in and near the settlements of Cache Creek and Ashcroft, southern British Columbia (Fig. 1), provide an opportunity to view some of the structures and rocks that help to explain the evolution and amalgamation of the allochthonous terranes of the southern Canadian Cordillera. Sediments and igneous rocks ofthe Cache Creek and Nicola Groups formed in late Paleozoic to late Triassic times in oceanic and island arc settings. The sediments of the Ashcroft Formation were deposited from Early through Middle Jurassic time in an arc-related basin. In Late Jurassic or possibly earliest Cretaceus time, thrust faulting juxtapose Cache Creek-Nicola rocks over Ashcroft strata. This event is thought to have sutured these terranes to Quesnellia of which the Ashcroft Formation is generally considered to be a part. This faulting may havebeen related to the early (Late Jurassic) deformationin the Omineca Crystalline Belt when east-directed thrust faults joined Quesnellia to that crystalline terrane.