STORM-DOMINATED SHALLOW MARINE DEPOSITS - FERNIE-KOOTENAY (JURASSIC) TRANSITION, SOUTHERN ROCKY MOUNTAINS

Six distinct facies can be defined. A: (thin bedded turbidites), and B: (thicker bedded turbidites) both have sole marks indicating N-NW flow. C is the most important and consists of interbedded sandstones and shales, with sole marks indicating N-NW flow, and 'hummocky cross stratification' as the characteristic internal sedimentary structure. It is interpreted to be formed by storm waves in depths below fair-weather wave base. D contains low angle intersecting sets of parallel lamination (beach) and E is characterized by trough cross bedding (fluvial). F consists of lenticular sandstones and shales, with coals. The facies occur in the sequence listed and indicate a N-prograding beach complex. Thus, the E-prograding Kootenay 'delta' of previous interpretations now appears to be a N-prograding beach complex fed by rivers, but with sand transported alongshore by waves.-from Authors