Welcome to the beautiful Frenchman River Valley! The Frenchman River Valley is a beautiful yet rugged area that was carved by glaciers many years ago. The valley begins on the outside edge of the Cypress Hills. Interestingly, the Cypress Hills were missed by glaciers, and stand as the highest point between the Rocky Mountains and the Atlantic Ocean. It’s climate and vegetation is more closely related to the foothills regions then the surrounding prairies. From the Cypress Hills it loops its way down to Eastend, passing through a more traditional prairie environment. After passing through Grasslands National Park, it eventually joins the Milk River in northeastern Montana.
As the great Glaciers retreated to form the land to later be known as the Frenchman River Valley, it was erosion that striped back the layers of time to revel the millions of years of the earths history. Stream erosion, as well as wind and rain, carved the plains to reveal that they were deposited in layers. The layers are composed of tiny grains of sediments such as sand, silt, and clay that have been cemented together into sedimentary rocks. The sedimentary rock layers were deposited during the late Cretaceous Period (67 to 75 million years ago) throughout the Late Eocene (34 to 37 million years ago) and Oligocene Epochs (26 to 34 million years ago). Different environments—sea, tropical land, and open woodland with meandering rivers—caused different sediments to accumulate here at different times. The layers similar in character are grouped into units called formations. The oldest formations are at the bottom and the youngest are at the top, illustrating the principle of superposition.
Types of Formations:
Sharps Formation
The lighter-colored layer, that form the peaks and Badland canyons, was deposited from 28 to 30 million years ago by wind and water as the climate continued to dry and cool. Volcanic eruptions to the west continued to supply ash during this time.
Rockyford Ash
The thick layer of volcanic ash was deposited 30 million years ago, forming the bottom layer of the Sharps Formation. The Rockyford Ash is a distinctive marker bed used in geologic mapping.
Brule Formation
This tannish brown layer was deposited between 30 and 34 million years ago. As the climate began to dry and cool, the forest gave way to open savannah. Bands of sandstone interspersed among the layers were deposited in channels and mark the course of ancient rivers that flowed from the Black Hills. Red layers found within the Brule Formation are fossil soils called paleosols.
Chadron Formation
This greyish layer was deposited between 34 and 37 million years ago by rivers across a flood plain. Each time the rivers flooded, they deposited a new layer on the plain. Alligator fossils indicate that a lush, subtropical forest covered the land. Most fossils found in this formation are from early mammals like the three-toed horse and the large titanothere.
Yellow Mounds
The sea drained away with the uplift of the Black Hills and Rocky Mountains, exposing the black ocean mud to air. Upper layers were weathered into a yellow soil, called Yellow Mounds. The mounds are an example of a fossil soil, or paleosol.
Pierre Shale
The black Pierre Shale was deposited between 69 and 75 million years ago when a shallow, inland sea stretched across what is now the Great Plains. Sediment filtered through the seawater, forming a black mud on the sea floor that has since hardened into shale. Fossil clams, ammonites, and sea reptiles confirm the sea environment.
Whitemud Clay:
The layering of sediments in an area such as the Frenchman River valley isn't all that uncommon. In fact most Bandland regions look quite simular or more impressive. What makes this area unique is the layers of Whitemud Clay that is squeezed between the layers of sediment. The above list of sedimentry layers is an amazing sight to see, but the bright white layers make this landscape and truly incredible sight to see. But what actually is this substance? The term “clay” refers to a varied group of soft, fine grained earthy materials which become plastic when moist. Clay minerals derive from ancient igneous and metamorphic rocks which have been weathered and altered over time. Clay deposits usually contain other minerals such as quartz, calcite and mica which affect their chemical and physical properties. The other interesting part about the layers of clay in this region is that the layer directly above the Whitemud clay is the layer that often contains various fossils that have made Eastend famous throughout the world!
Although it is no longer mined in the area, the nearby Whitemud Pits was a huge business in the early part of the Nineteen hundreds. (As you will know if you have already visited Chocolate Peak and learned of the extreems some miners went to to mine the clay) Clays, with their varied physical and chemical properties, play an important role in many industries, including the construction, mining, manufacturing, artistic, chemical and oil and gas industries. At present, three major companies produce clay products in Saskatchewan. Clays have been used for structural products since long before Saskatchewan was a province. Homesteaders mixed raw clay with straw to make bricks and stucco. Sometimes clay was used to create works of art. Small brick making factories scattered around the province supplied local building markets. Early industries such as those at Claybank, Estevan and Bruno manufactured bricks, stoneware and earthenware pottery and fire brick products.
The Frenchman River Valley and surrounding country is filled with wildlife such as whitetail and mule deer, antelope, coyotes, rabbits, and perhaps even moose. While best viewed at dusk and dawn, be sure to lower your speed to avoid a potential collision.
Ground Zero can easily be found west of Eastend, Sk. From Eastend travel North on Grid 616 (Brady Coulee Road) and take your first left onto Grid Road 716, which you follow until Ground Zero where there is a turnoff at which you can park. To register this find, you need to answers the following questions. I always try to respond to your emails ASAP, but if I don't respond it is safe to assume your answers are correct. I've also noticed recently that “teams” are having one member send in the answers for the rest of the team. This is fine by me but please note the names in the answer email so I can cross reference the logs with the answers. As always please do not post your answers with your log . . . please email them to me directly:
1. List the colours of layers that you see in the hills directly North of your location. What formations do they belong to?
2. How old is the oldest formation?
3. How old do you suspect the Whitemud Clay layers are based on their location between the other sediment layers?
4. What are a few present day uses of Whitemud Clay?
5. (Optional Task) Post a picture of yourself at ground zero. Try not to include pictures that will give away the answers to the questions/
Please note that this is an Earthcache, which means there is not a physical cache at ground zero. For more information on Earth caches, please visit www.geocaching.com or www.earthcache.org.
Sources:
http://www.wdm.ca/skteacherguide/WDMResearch/Saskatchewan's%20Clay%20Resources%20by%20Janet%20MacKenzie.pdf
http://www.nps.gov/badl/naturescience/geologicformations.htm
https://www.dmr.nd.gov/ndgs/NDNotes/ndn13_h.htm
http://www.dinocountry.com/?s=286&p=286&0=286