INTKODUOTION. XV 



time, but belonged to many different periods of the earth's 

 history. Their destruction and burial, therefore, could not 

 be ascribed to any single great catastrophe. It was demon- 

 strated that during past ages the distribution of land and 

 sea, mountains and plains, had frequently changed — that, in 

 fact, rain, rivers, waves, currents, volcanoes, and phenomena 

 like earthquakes, were continually altering the earth's 

 surface, even under the eyes of man himself. The fossils 

 were proved in most cases to be buried in displaced portions 

 of sea-bottom, and in the mud of dried-up lakes ; and it was 

 realised that the relative ages of these deposits could be 

 determined by the order in which they lay one upon 

 another. Thus arose the true " science of the earth," which 

 was named Geology by De Luc in 1778. 



An English civil engineer, William Smith (1769-1839), 

 was perhaps the first to realise fully the possibilities of this 

 new branch of learning. His profession necessitated much 

 travel through the country, and his interest in the distri- 

 bution of fossils in the different kinds of rock led him to 

 make a large collection, which was acquired by the British 

 Museum in 1816, and is now exhibited in Gallery No. 11 

 of the Department of Geology. His published maps and 

 writings prove that the various features of the landscape, 

 in districts where fossils occur, are naturally carved out of 

 layers of rock, which are simply old sea-beds or lake-beds 

 piled one upon another, the oldest at the bottom, the newest 

 at the top, each containing its own definite and invariable 

 set of fossils. They also show that in most cases when these 

 old sediments were raised into dry land, they were tilted in 

 various ways from their originally horizontal position ; so 

 that it is often possible in a short walk to pass over the cut 

 edges of many successive layers, perhaps hundreds of feet in 

 thickness, representing immense periods of time. 



While Smith and others were busily engaged in collecting 

 fossils and observing their distribution, Blumenbach, Cuvier, 

 Lamarck, Brongniart, and other naturalists were occupied 

 with a detailed study of the fossils themselves. They soon 

 demonstrated that, while most of these petrified remains 

 could be interpreted by comparing them with the life of the 

 present world, a large proportion represented animals and 

 plants no longer existing. They also observed that the 

 older the fossils, the more strikingly different they were 

 from any animals and plants now living. It therefore 

 became evident that fossils afforded a means of discovering 



