23 
Section 4. 
Along the northern edge of Devils gap, the narrow, steep-sided valley 
which forms the eastward continuation of the Lake Minnewanka valley 
into the valley of Ghost river. The section extends from the northwestern 
end of West lake eastward to the gully at the western end of Middle lake. 
Banff Shales (Lower Mississippian) 
(1) Rather thin-bedded, coarse to fine-grained dolomitic limestones 180 feet 
Fossils rare. 
(2) Heavy-bedded, coarse to fine-grained dolomitic limestone 160 feet 
Fossils abundant in places. 
(3) Upper part heavy-bedded, coarse-grained dolomitic limestone, with a 
few thin (2 to 6 inches thick) shaly limestone partings. These shaly beds become 
more numerous and thicker towards the base. The lowest 20 feet contains many 
chert nodules 50 feet 
These beds are very rich in fossils, especially the more shaly beds. 
(4) Black, finely-laminated, fissile, calcareous shales, quickly weathering 
brown; partly covered. Correlated with section 2, localities 36 and 37 300 feet 
Minnewanka Limestone (Upper Part) ( Devonian ) 
(5) Alternation of shaly limestone with brownish weathering, crossbedded 
shales 170 feet 
The upper 10 feet, a shaly limestone, are fossiliferous. 
(6) Coarse to medium-grained, dark grey limestone. The upper part con- 
tains many algal forms 600 feet 
Much of the Minnewanka limestone is lost in this section by a fault. 
Minnewanka Limestone (Lower Part) (Devonian) 
(7) Mostly a coarse-grained dolomite, weathering pitted and emitting when 
struck a strong odour of hydrogen sulphide 750 feet 
(8) Rock mostly similar to that of the last locality, with many included cal- 
careous geodes averaging about 2 inches in diameter. Some of the strata are 
crossbedded. A few of the upper beds are black, fine-grained, fissile shales 200 feet 
(9) Coarse-grained dolomite, with many calcareous geodes and algal forms. 
When struck the rock yields a strong hydrogen sulphide odour 250 feet 
(10) Similar to locality 9, with the basal 2 feet crossbedded 40 feet 
Ghost River Formation ( Age ? ) 
(11) Similar to the last, but fine grained, with minor crossbedding and 
weathering yellowish 90 feet 
(12) Similar to locality 13, alternating with a fine-grained dolomite with 
light grey chert concretions 80 feet 
(13) Where not concealed, a fine-grained dolomite and yellow grey sand- 
stone, with minor crossbedding, weathering a bright yellow 100 feet 
Castle Mountain Group (Middle Cambrian) 
(14) Dense, rather thin-bedded, fine-grained dolomite, in many cases 
seamed in all directions with numerous calcite veins. There are many algal or 
pencil-like formations, probably dolomitic segregations, parallel with the bedding 
plane. Considerable minor crossbedding present 270 feet 
(15) Greenish, shaly limestone 2 feet 
The upper 6 inches are almost entirely composed of trilobite tests. 
(16) Rock similar to that of locality 14, but heavy bedded. The uppermost 
2 feet a black fissile shale 300 feet 
This takes to the western side of the gully at the western end of the 
middle lake in the gap. 
