Having undertaken to explain the geology of the Cheddar gorge to the Cotteswold Naturalists' Field Club at one of their field-meetings this Summer, I thought I should do so more intelligently if I first acquired a practical knowledge of my subject. I accordingly paid a preliminary visit to Cheddar. There were two chief questions to be investigated: (1) the origin of the gorge, and (2) the cause of its serpentine, or rather zigzag, course. The former inquiry had been answered in four different ways. There had been geologists who held that the valley had been excavated by the waves of the sea. A second school taught that it had been produced by a dislocation, splitting the rocks asunder. The third theory regarded it as a valley of erosion, excavated in the ordinary way by a river on the surface. A fourth explanation placed the river underground, and maintained that the glen had originally been a long winding cavern, the roof of which had subsequently fallen in.