Crinkle cracks are sand-filled cracks up to 5 mm wide in plan view that pinch at their ends. In cross section, they are canted and crinkled. They cut mudstone beds that underlie hummocky cross-laminated sandstone lenses. They are here described from the Piegan Group, Proterozoic Belt Supergroup, but they are widespread in Proterozoic and Phanerozoic marine and lacustrine rocks. However, they represent a distinctive, descriptive style of mudcracks, not attributed to inferred syneresis processes, although they have been commonly attributed to syneresis. In plan view, crinkle cracks closely resemble cracks formed where oscillatory waves striking viscous mud banks are transformed into fluid solitary-like waves that open surface cracks on their trailing limbs and close the cracks on their leading limbs as they pass through the viscous mud. Crinkle cracks preserved in rocks are hypothetically attributed to oscillatory waves moving sand over viscous mud. The oscillatory waves are transformed into solitary-like waves as they pass down into the mud, forming the cracks. The surface sand falls down into the cracks, preserving them. With burial, the water escapes, and the viscous mud compacts, crinkling the sand-filled cracks.

Abstract: Species of reef corals are identified within lithologic units in the two Bahamas Drilling Project cores (Unda and Clino); species richness, frequencies of different colony shapes, and occurrences of indicator species are used to interpret reef environments. The results suggest that twelve Pliocene-Pleistocene coral-bearing units in the upper portions of Unda (26.2-180.8 m) were deposited under generally shallowing-upward conditions, ranging from intermediate (10-20 m) or deeper (> 20 m) forereef environments, to shallow (0-10 m) forereef environments, to shallow (0-10 m) and intermediate-depth (10-20 m) platform environments, in contrast, five Upper Miocene coral-bearing units in the lower portions of Unda (298.1-376.7 m) were deposited under generally deeper conditions, including (1) a small intermediate-depth (10-20 m) or deeper (20 to > 30 m) reefal unit and (2) intermediate-depth (10-20 m) to deeper (20 to > 30 m) forereef environments with large numbers of plate-shaped corals. Like the upper portions of Unda, eleven Pliocene-Pleistocene coral-bearing units in Clino (26.2-197.5 m) formed under shallowing-upward conditions, ranging from intermediate-depth (10-20 m) and deep (20 to > 30 m) forereef environments, to shallow (< 10 m) forereef environments, to shallow (< 10 m) or intermediate (10-20 m) platform environments. However, middle forereef deposits in the upper portions of Unda contain diverse assemblages dominated by Stylophora , whereas middle forereef deposits in Clino are dominated by Acropora . These interpretations generally correspond well with those based on lithology, and indicate that coral assemblages provide unique and important criteria for interpreting Late Cenozoic reefal deposits.

Abstract The mining of zinc in Tennessee dates back to 1854 although the presence of zinc minerals had been reported as early as 1844 by Gerard Troost, the first State Geologist. When the Mossy Creek open pit mine, in what is now Jefferson City, Jefferson County, was opened, it became the first mine in what is now known as the Mascot-Jefferson City Zinc District. In these early years, only the oxidized ore was removed, and mining stopped when the sulfide ore zone was reached because a method to treat “hard ore”, as it was called, had not yet been developed. Mining continued at the Mossy Creek operation until 1858, then ceased through the Civil War years until 1867, at which time the property was taken over by the East Tennessee Zinc Company. This company built a smelter to manufacture zinc oxide, but after only a few months of operation, the company became involved in litigation and mining ceased. In 1882, the Mossy Creek property was sold to the Eades, Mixter and Heald Zinc Company which operated intermittently until 1894, becoming the first substantial zinc mining company in Tennessee as well as the first to produce significant amounts of sulfide ore. This latter was made possible by the construction of a zinc smelter at Clinton, Tennessee, some 45 rail-miles to the west. The Mossy Creek mine was operated or prospected only sporadically thereafter, and was closed by its final owner, the American Zinc Company, in 1919. In the meantime, the discovery of lead and zinc ore in the Powell River area of Claiborne and Union Counties, some 30 miles northwest of Jefferson City, caught the attention of the mine operators. In 1883, the New Prospect mine was opened with only the lead recovered. By 1889, Eades, Mixter and Heald had taken over, erected a mill and mined the property intermittently until 1897. The lead was handpicked and shipped to New Jersey while the zinc was barged to the smelter at Clinton. There was little further activity until World War II when the very high grade pillars were robbed. The only other producing mine in the Powell River district was at Straight Creek. It operated from 1880 to 1894, the latter part of this period by Eades, Mixter and Heald Zinc Company, which also built a mill. Beyond this there was only a short period of exploration and mining from 1906 to 1908 and another effort by Universal Exploration Company in the latter part of World War II.