Soils and paleosols were investigated from pre-Reid (early Pleistocene), Reid (Illinoian or early Wisconsinan) and McConnell (classical W.isconsinan) surfaces in central Yukon. Paleosols on the pre-Reid surface indicate that it was subjected to two distinct climates, an initial one which was warm and subhumid with grassland-shrub vegetation and later a more temperate and humid climate characterized by the development of a Luvisol with a red, textural B horizon, in places over 190 cm (75 in) thick. Subsequently, the climate became colder, resulting in the Reid glaciation. Thermal contraction cracks developed in the pre-Reid deposits beyond the limit of Reid glaciation and were filled with eolian sand, as well as minor silt and clay, to form sand wedges. During the subsequent Reid-McConnell interglacial, a cool, subhumid climate prevailed as evidenced by the Brunisolic characteristics of paleosols on deposits of Reid age. This was followed by a cold period which climaxed with the advent of the McConnell glaciation. Sand wedges also formed in the deposits of the Reid glaciation; the wedges are shallower and narrower than those on the pre - Reid surface, suggesting a shorter cold period. During retreatal stages of the McConnell glaciation, a thin blanket of loess was deposited over McConnell, Reid and pre-Reid surfaces, covering the soils on the Reid and pre-Reid surfaces during post - glacial (Holocene) time. Finally, Brunisolic soils developed on the loess blanket and, locally, where the loess is very thin or lacking, on deposits of McConnell age.

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Abstract--Clay minerals from shale outcrops of the Lower Cretaceous Buckinghorse Formation (4250 fl thick) were investigated in order to assess their degree of diagenesis and their oil-generating potential. Crystallinity index, sharpness ratio, per cent of illite which is the 2M polymorph and presence of discrete minerals have been studied in the whole clay fraction, while the very fine clay fraction has been subjected to X-ray diffraction, differential thermal, thermogravimetric, differential thermogravimetric, i.r. spectroscopy, surface area and chemical analyses. With information derived from these studies and from published data, a classification scheme was devised which relates variation of clay mineralogy to diagenetic stages and burial depth. Data on the < 2 #m size fraction show that the crystallinity index decreases while the sharpness ratio and per cent of illite which is the 2M polymorph increase with burial depth. Results on the <0.08/zm fraction reveal that a three-component interstratified clay mineral exists. In addition, Fourier transform calculations and chemical and physicochemical analyses indicate that both the ratio of the amounts of nonhydrated clays (illite) to hydrated clays and the K2O content of clays increase with burial depth: cation exchange capacity and surface area decrease with burial depth.

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