Old bulldozer cuts and trenches expose a 3 to 5 metre thick bentonitic clay and siltstone bed lying between sequences of interbedded sandstone, siltstone and shale of the Middle Eocene Coldwater Formation (Princeton Group).

Sample C86-410A from this location yielded the following exchangeable cation analyses and cation exchange capacity (CEC) in milliequivalents per 100 grams: magnesium 9.4; calcium 19.4; potassium 2.1 and sodium 15.0 with CEC 47.6. Sample C86-410E comes from a roadcut above the highway and yielded magnesium 9.2; calcium 12.5; potassium 1.8 and sodium 9.7 with CEC 32.1 (Fieldwork 1986).