Cypress Hills Interprovincial Park the Hills Continue to Change
Total Page：16
File Type：pdf, Size：1020Kb
are made from sediments which have been deltas, rivers and swamps deposited mud and Tertiary Period. During the Palaeocene Epoch, deposited by water, and then compressed and sand on top of the Bearpaw shale. Light grey rivers and swamps continued to deposit cemented into rock. The grain size of the rock and brown sandstones and interbedded dark grey sediments in the are, forming the sandstone, indicates the environment in which the shale originated in brackish fresh water, while siltstone, coal and shale of the Ravenscrag sediments were deposited. For instance, thin coal layers formed from decayed vegetation Formation. Beginning about 55 million years gravels are only deposited by fast moving in swamps. These rocks make up the thick ago major mountain building to the west formed streams, while fine clays are deposited in still Eastend Formation. As the sea receded, the thin the Rocky Mountains. Large rivers eroded the water. Most formations are predominantly a Whitemud Formation, consisting of a fine, white new mountains and deposited gravel and single rock type, with thin interbedded layers clay with some interbedded sandstone and shale, cobbles across the western plains, which a semi- of other rock types. was formed in still, fresh waters. arid environment had turned into a broad savanna. The uplift of the Sweetgrass Hills, For a relatively short time, a brackish around 50 million years ago, caused other rivers semi-marine environment returned, leaving to carry the cobbles and gravel across the behind the purple-grey shale of the thin Battle Cypress Hills area during the late Eocene, early Formation. Active volcanoes far to the west also Oligocene, and Miocene Epochs. The gravel deposited layers of ash across the area at this and cobbles formed a conglomerate rock, called time. The Kneehills Tuff, a 20 cm ash layer the Cypress Hills Formation – now the found in the Battle Formation, has been dated at uppermost sedimentary layer which caps the 66 million years old. Later, deposition stopped Cypress Hills. in the area and some erosion took place, creating an unconformity in the geological record. Divide & Erode Subsequently, large meandering rivers returned Over time, geological processes A High Plateau to the area, laying down sediments which formed slightly elevated the Cypress Hills region. The The highest point in mainland Canada the grey and brown sandstones and thin sedimentary layers remained nearly horizontal, interbedded shale of the Frenchman Formation. between Labrador and the Rocky Mountains, the but the area became a drainage divide. For Cypress Hills form a high plateau surrounded by millions of years, large rivers originating in the a rolling upland. Climbing sharply from the mountains were forced to flow around this north, the Cypress Hills reach their highest In the Beginning divide, lowering the surrounding land and elevation (1466m) at Head of the Mountain, The geological story of the Cypress Hills isolating the Cypress Hills as a high plateau. before gradually dropping back to the plains in begins during the Cretaceous Period more than Resistant to erosion, the hard conglomerate cap the south. Formed by millions of years of 70 million years ago, when most of southern protected the softer rocks of the underlying sedimentary deposition, followed by millions of Alberta was covered by the warm, shallow years of erosion, the Cypress Hills are known as Bearpaw Sea. Large rivers from the west an erosional plateau. Today, the Cypress Hills carried clay and silt which settled onto the sea expose a unique cross-section of geological floor. These sediments were compressed into a history found nowhere else in western Canada. dark grey flaky shale, now called the Bearpaw Formation, which forms the base of the Cypress Hills. A Layer Cake The Cypress Hills resemble a giant layer cake, composed of many layers of Streams, Swamps &Sediment sedimentary rocks. Each layer, called a By about 68 million years ago the Bearpaw Sea formation, formed at a different time under About 65 million years ago the had retreated to the east. The area became a dinosaurs became extinct, marking the end of the different conditions. The youngest formations forested, semi-tropical coastal region where are found higher in the hills. Sedimentary rocks Cretaceous Period and the beginning of the formations, ensuring that the area remained a The Changing Hills flat-topped upland. Even before the Ice Age, the By 10,000 years ago, the ice age was For More Information Cypress Hills had essentially developed their over. The last of the major geological Many geological features are visible present form. processes playing a part in the formation of the throughout Cypress Hills Interprovincial GEOLOGY Cypress Hills had ended, but even to this day, Park. Staff would be happy to direct you to Cypress Hills Interprovincial Park the hills continue to change. Erosion from these sites. For more information, drop by The Ice Age streams and sudden thunderstorms deepens the one of the Visitor Centres, or write to: As the climate cooled during the coulees and ravines, while slumping and Pleistocene Epoch, huge continental ice sheets landslides wear away at the edges of the Cypress Hills Interprovincial Park crept south. Glaciers flowed around the Cypress Cypress Hills. Box 12 Box 850 Hills plateau but never completely engulfed it. Elkwater, AB. Maple Creek, Sk. The top 100 meters of the plateau was left an Fossils T0J 1C0 S0N 1N0 island, called a nunatak, above the surrounding (403) 893-3777 (306) 662-4411 Throughout the geological history of ice. The surrounding land and the lower portions the Cypress Hills, living creatures have of the hills were sculpted and eroded by the ice Text: Michael Klassen, Alberta Parks flourished in the area. Some are now preserved sheets. As the ice sheet finally began to melt Illustrations: Keli Polock, Alberta Parks as fossils. Marine mollusks – ammonites and about 15 000 years ago, large amounts of till – a baculites – occur in the Bearpaw Formation, mixture of silt, sand and gravel – was dumped while Triceratops and other fossils from the into the plains and the flanks of the hills. High age of dinosaurs are occasionally found in the winds swept across the bleak landscape; Frenchman Formation. The eastern portion of blanketing the top of the unglaciated plateau with the Cypress Hills Formation contains abundant thick deposits of silt called loess. Meltwater fossils of many strange and extinct mammals, coursed between the plateau and the retreating including titanotheres, camels and sabre- ice, carving out the valleys which now dissect toothed cats. A reminder that collecting fossils Rising more than 600 meters above the many parts of the Cypress Hills. and rocks in a provincial park is prohibited. surrounding prairies, the Cypress Hills are a striking geological anomaly on the Coal, Clay & Cobbles flat plains. Unlike the Rocky Many of the formations of the Cypress Mountains, these hills do not owe their Hills contain resources of economic importance. Although of poor commercial existence to the faulting and folding of a quality, the coal seams of the Eastend geological uplift. Read this fact sheet to Formation were mined for local use in the early discover the unique geological history part of the century. The Whitemud formation of the Cypress Hills is the most important source of ceramic clay in Western Canada, supporting the local pottery, pipe, brick and clay industries for many years. The large cobbles of the Cypress Hills Fact Sheet Formation were once used for grinding phosphate in the manufacture of fertilizer. Gravel deposits were also mined for construction purposes. Mining, no longer permitted in the park, once played an important role in the development of the area..