11 
Aldridge Formation 
The Aldridge formation, exposed along the railway east of Cranbrook, 
is made up of a series of argillaceous quartzites, purer quartzites, and 
argillites. The argillaceous quartzites form* about three-quarters of the 
whole series and occur in beds with an average thickness of one foot. 
They are fine-grained rocks, dark grey to black on fresh fracture, and 
weather rusty brown, the most distinctive feature of the formation as a 
whole. 
Creston Formation 
The Aldridge formation passes by gradual transition into the over- 
lying Creston quartzites. The lithology may be examined in the cuts along 
the wagon road from Cranbrook to Wycliffe. The Creston formation 
embraces a succession of greyish argillaceous quartzites and purer quartzites 
whose beds average about one foot in thickness. They are light grey on 
fracture and weather in greyish tones in contrast with the rocks of the 
underlying Aldridge formation. 
Kitchener Formation 
In comparison with the underlying Creston and Aldridge formations, 
the most notable feature of the Kitchener formation is its content of lime. 
These rocks are exposed in the low hill north of the intersection of the 
Cranbrook-Fort Steele wagon road and the Canadian Pacific railway, 
about 3 miles east of Cranbrook. The formation consists of calcareous 
and argillaceous quartzites and impure limestones in beds about 6 inches 
thick. The rocks are grey on fresh fracture, but weather, as a rule, yellowish 
brown and grey. The weathered surface of the limy members is pitted 
and marked parallel to the bedding planes by numerous linear depressions 
about one-eighth to one-quarter inch wide and one-half inch deep, whereas 
on the planes perpendicular to the bedding, these depressions are irregular 
and somewhat vermicular. 
Siyeh Formation 
The lower part of the Siyeh formation is composed of thin-bedded 
green and purple mud-cracked metargillites and sandstones. About 2,000 
feet above the base of the Siyeh formation occur thin-bedded and massive 
siliceous and concretionary limestone, grey on fresh fracture and weathering 
usually a buff colour. These limestones, which are about 1,000 feet thick, 
are succeeded by purple and green mud-cracked metargillites in thin beds. 
Purcell Lava 
Near the top and interbedded with the rocks of the Siyeh formation 
occur flows of basalt from 50 feet to 300 feet in thickness. The top of the 
Siyeh formation is marked by one of these flows. The dominant rock of 
the Purcell lava is mainly a highly altered amygdaloidal or porphyritic 
basalt. The flows are generally heterogeneous in character. 
