Clerestory

In Gothic architecture, nave above the roofs of the aisles, so called from the windows which light immediately overlying the Medina Sandstone. In these beds in Pa. occur the remains of the oldest American vertebrates. See SILURIAN and PALÆASPIS. IMG:content-0908.png:[blocks in formation] Wojeikoff distinguishes the zones according to the quantity and character of the rainfall: Its