Geology of the Chinchaga River and Clear Hills (North Half) Map-Areas, Alberta

The Chinchaga River and Clear Hills (north half) map-areas comprise an area of 7500 square miles in the Plains region of northwestern Alberta. The area is part of a large dissected plateau composed of concordant, flat-topped hills surrounded by gently undulating lowlands. It is underlain by nearly flat lying rocks of Late Cretaceous age covered by unconsolidated glacial and alluvial deposits of variable thickness.

The Cretaceous succession consists of alternating marine and non-marine sandstones and shales with an aggregate thickness of 4000 feet. The rocks can be divided into six formation units correlative with the Shaftesbury, Dunvegan, Kaskapau, Bad Heart, Puskwaskau and Wapiti Formations in adjacent areas.

Ferruginous, oolitic sandstones are locally present in the lower Kaskapau and Bad Heart units in the southern and eastern parts of the area. The thickest iron-rich deposits are of Bad Heart age and are present near Worsley and on Swift Creek in the Clear Hills. Thinner deposits of early Kaskapau age are locally present near the northern edge of the Chinchaga Hills.