“Geologists should think to scale”; so Professor Daly has urged in one of his illuminating writings. Returning from a visit to the Rift Valley country, I realize that in the past I have failed to picture these remarkable valleys to scale. Perhaps I received a wrong impression in the beginning from the rather extravagant language used by some of the earlier writers: “a yawning abyss,” says one; “walls as steep and abrupt as those of a grave,” says another; “in many parts the walls are so precipitous that not even the most expert of cragsmen could scale them,” says a third. Then the well-known drawings of the arch and the sunken keystone, and the rival diagram of the great ramps with a depressed block between them—although I knew that these were only diagrams, not scale drawings, I fear they played their part in perpetuating the early, extravagant impression. So it came to pass that when I stood at last between the walls of the great depression, the glow of satisfaction brought on by the realization of a long-cherished wish was chilled by a rather childish disappointment. Mine was not the case of the man who was shown a giraffe and said “I don't believe it!;”; I believed in the giraffe, but it didn't come up to expectation!