PALEOSOL MICROMORPHOLOGY OF THE MIDDLE DEVONIAN CAIRO QUARRY FOSSIL FOREST

The Cairo Quarry Fossil Forest is an exceptionally well preserved Middle Devonian paleo-landscape near the base of the Catskill Clastic Wedge. The forest is exposed in plan view spanning ca. 2655m² across the quarry, and preserves at least 3 different tree types. Micromorphology of the paleosol associated with this fossil forest was analyzed over a small area using surface collections in order to derive interpretations of ancient soil processes and landscape characteristics. The fossil forest is rooted within a mottled reddish-green horizon that is both underlain and overlain by a greenish-gray mudstone. The reddish green horizon preserves oriented clay fabric suggestive of clay translocation and weakly developed vertic properties, reddish mottles and glaebules of iron oxides indicative of a fluctuating water table, and organics as either drab haloed root traces or carbonized fragments throughout matrix. The underlying grayish-green silty mudstone preserves oriented clay fabric suggestive of clay translocation and weakly developed vertic properties. Organics are preserved as carbonized fragments, and as masses of secondary framboidal pyrite from the biologically mediated anaerobic decay of organic material. The overlying grayish-green silty mudstone preserves relict bedding that is crosscut by zones of oriented clay fabric suggestive of weakly developed vertic properties. Organics are preserved along relict bedding as carbonized films, as randomly scattered fragments throughout the matrix, and as framboidal pyrite from anaerobic decay. Of particular interest is the presence of numerous carbonized fish fossils at the very top of this uppermost grayish-green layer. As a whole, the micromorphology of the Cairo Quarry paleosol supports an interpretation of a lowlying forested landscape that was subjected to fluctuating water tables. The uppermost grayish-green layer represents a flooding event that buried the forest floor and stranded numerous fish. Paleosols underlying the fossil forest in Cairo Quarry are black, carbonaceous profiles that would have formed on lower, persistently waterlogged parts of the paleo-landscape. As a whole, the paleosols at Cairo Quarry suggest a nearshore fluvio-deltaic setting. Within modern soil taxonomy, these soils would be most similar to aquents and aquerts.