The Porcupine Hills Formation is a stratigraphical

Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

 unit of Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 age

Geochronology

Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

 in the Western Canadian Sedimentary Basin

Western Canadian Sedimentary Basin

The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...

.

It takes the name from the Porcupine Hills in south-western Alberta

Alberta

Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, and was first described in outcrop by George Mercer Dawson

George Mercer Dawson

Dr. George Mercer Dawson F.R.S., C.M.G., was a Canadian scientist and surveyor. He was born in Pictou, Nova Scotia, the eldest son of Sir John William Dawson, Principal of McGill University and his wife, Lady Margaret Dawson...

 in 1883.

Lithology

The Porcupine Hills Formation is composed of brown shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

 interbedded with calcareous sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

 and siltstone

Siltstone

Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...

. The grains are represented by detrital quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

, chert

Chert

Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...

 and carbonate

Carbonate

In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....

s.

Distribution

The Porcupine Hills Formation occurs only in south-western Alberta

Alberta

Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, from the Porcupine Hills area in the south to the Bow River

Bow River

The Bow River is a river in the Canadian province of Alberta. It is a tributary of the South Saskatchewan River, and is considered the headwater of the Nelson River....

 in the north. It has been eroded elsewhere. The upper limit is the present day erosional surface, so initial thickness can not be determined; however, the maximum recorded thickness is 1200 metres (3,937 ft) in the Porcupine Hills.

Relationship to other units

The Porcupine Hills Formation is exposed at surface or is overlain by Quaternary

Quaternary

The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...

 deposits.It overlays the Willow Creek Formation

Willow Creek Formation

The Willow Creek Formation is a geological formation in Alberta, Canada whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation....

 conformably and transitionally. Towards the north and east it overlays and grades into the Paskapoo Formation

Paskapoo Formation

The Paskapoo Formation is a stratigraphical unit of Paleocene age in the Western Canadian Sedimentary Basin.It takes the name from the Blindman River , and was first described in outcrops along the river, north of Red Deer by J. B...

.

It is equivalent to the Ravenscrag Formation

Ravenscrag Formation

The Ravenscrag Formation is a stratigraphical unit of Late Cretaceous to Tertiary age in the Western Canadian Sedimentary Basin.It takes the name from the settlement of Ravenscrag, Saskatchewan, and was first described in outcrop at Ravenscrag Butte near Frenchman River by N.B...

 in southeastern Alberta

Alberta

Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

 and southwestern Saskatchewan

Saskatchewan

Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....

.