Origin of some intermittent ponds on quartzite ridges in western North Carolina

Several intermittent ponds and closed depressions as much as 200 feet wide occur on the crests of ridges in gently dipping Cambrian(?) quartzites in the southeastern foothills of the Blue Ridge Mountains near Morganton, North Carolina. The unconsolidated fill and debris in the ponds consists of clayey sand and saprolite with accessory minerals that could have been derived entirely from the quartzite. The pond water contains appreciable quantities of dissolved silica and with the aid of organic substances could have formed the depressions by solution since the beginning of the Pleistocene.