This is a "badlands" slope in the Frenchman river valley. The valley exposes the "Whitemud Formation" in many places (clearly visible here half way down on the left). Two surface mines of Plainsman Clays are nearby (over the top and down the other side), in a place where lower-lying rolling hills leave much less over-burden to remove. To the left of this is a former mine of I-XL brick. This is also the site of a mine for the former Medalta Potteries. These materials were laid down as marine sediments during the Cretaceous period. Below the Whitemuds are formations from the Jurassic period. The skeleton of the world's largest T-Rex, dubbed "Scotty", was found 50km east of here (in the layers just above the Whitemuds).
Plainsman Clays did 6 weeks of mining in June-July 2018 in Ravenscrag, Saskatchewan. We extracted marine sediment layers of the late Cretaceous period. The center portion of the B layer is so fine that it must have wind-transported (impossibly smooth, like a body that is pure terra sigillata)! The feldspar and silica are built-in, producing the glassiest surface I have ever seen at cone 6 (2200F). Despite this, pieces are not warping in the firings! I have not glazed the outside of this mug for demo purposes. I got away with it this time because the Ravenscrag clear glaze is very compatible (similar thermal expansion). But with other less compatible glazes they cracked when I poured in hot coffee. This mug was the beginning of an exciting project the sieve out +325 mesh particles any make many more pieces.
These amazing hills near Big Muddy, Saskatchewan expose the sedimentary layers of the Whitemud formation (and others). The light-colored layer at the bottom is what Plainsman calls A3, it makes up about half of M340. But below ground is the 3B layer, the other half. The dark grey layers above the Whitemuds are what we call A2, a ball clay. Of course, top soil has accumulated on top of the clay to be able to grow plants. Although this is about 250km east of the Plainsman quarry at Eastend, Saskatchewan - the clay layers are remarkably similar. The clay resources in the area are truly astounding, not just in the quantity and quality but also in the magnificent landscape they define.
Ravenscrag Slip is Born
The story of how Ravenscrag Slip was discovered and developed might help you to recognize the potential in clays that you have access to.
Medalta Potteries, Medalta Stoneware
T.Rex Discovery Centre