Nineteen shales from the continental Belly River Formation and sixteen shales from the marine Wapiabi Formation were studied by X-ray diffraction and fluorescence methods. The diffraction data indicate that dolomite and Mite are present in signifi- cant amounts only in the Wapiabi. Feldspar and 12 Å and 14 Å clays are more abundant in the continental shales. The marine shales are enriched in K, Ca, Rb and Zr. The continental shales are higher than marine shales in Sr and Mn. The Rb/K is higher in the marine shales, the Sr/Ca is lower than in the continental shales.