The Cypress Hills reach a maximum elevation of , rising about above the surrounding plains. This makes the Cypress Hills the highest point in Canada between the
Rockies and
Labrador. They are the remnant of a more widespread
plateau, most of which has been removed by erosion. The plateau is capped by the resistant
conglomerate and
sandstone beds of the
Cypress Hills Formation. That formation was deposited by rivers that flowed from the mountains of southwestern Alberta and northwestern
Montana during late
Eocene to middle
Miocene time, and is known for its wealth of vertebrate fossils. During the
Pleistocene, the top of the Cypress Hills was not overridden by the
Laurentide Ice Sheet and remained unglaciated. As the ice sheet paused periodically during its final retreat, a series of
morainal ridges of
glacial till built up around the hills. Rivers of
meltwater cut large channels through the area as the retreat continued, and smaller streams carved
coulees and areas of
badlands. Today the Cypress Hills are part of a major
drainage divide that separates rivers that drain south to the
Gulf of Mexico via the
Missouri River system from those that drain to northeast to
Hudson Bay via the
Nelson River system. At the Dividing Springs Ranch northwest of
Eastend, Saskatchewan, the water from a spring goes both south to Gulf of Mexico and northeast to Hudson Bay. ==Ecology==