PPT Slide
The quartz veins at Diamond Hill were emplaced into a granitoid pluton (Antreville Pluton) as a result of series of late Paleozoic Era tectonic events. The Antreville pluton, itself, was intruded during the Taconic orogeny that extended from late Ordivician to Early Silurian Periods. Heat and pressure from Paleozoic regional metamorphism transformed the rock into granitoid gneiss. Silica-rich hydrothermal fluids entered fractures within the metamorphosed pluton and deposited the quartz veins. These veins must have contained voids that would later become sites for quartz crystals to form during a series of subsequent hydrothermal events. All of these geological processes took place miles beneath the present earth's surface. It took over several hundred million of years of erosion to uncover the rocks. The granitoid gneiss has been deeply weathered resulting in the development of a thick soil zone made up of rock weathered in place. Such in situ weathered rock is called saprolite. Oxidation of iron bearing minerals formed clay that was transported by infiltrating meteoric water into the quartz-lined pockets. Much of the quartz and saprolite is heavily stained with red, brown, yellow and black iron and manganese oxides.