548 POPULAR SCIENCE MONTHLY. 



for entertaining, at least, the idea of man's origin by a natural 

 process of evolution. 



Evidences of the work of man — flint implements, associated 

 with the bones of extinct animals and therefore sho\ving much 

 greater age than usually accepted — had been reported from time 

 to time, notably those found in the river Somme by Boucher de 

 Perthes. But the prejudice against such antiquity was so strong 

 that geologists with one accord, and without examination, pooh- 

 poohed all such evidence as incredible. It was Sir Joseph Prest- 

 wich who, in 1859, first examined them carefully, and published 

 the proofs that convinced the geological world that early man was 

 indeed contemporaneous with the extinct animals of the Quater- 

 nary period, and that the time must have been many times greater 

 than usually allowed.* 



Since that time confirmatory evidence has accumulated, and the 

 earliest appearance of man has been pushed back first to the late 

 glacial, then to the middle glacial, and finally, in Mr. Prestwich's 

 Plateau Gravels, to the early glacial or possibly preglacial times. 



Still, however, in every case earliest man was unmistakably 

 man. No links connecting him with other anthropoids had been 

 found. Very recently, however, have been found, by Du Bois, in 

 Java, the skull, teeth, and thigh bone of what seems to be a veri- 

 table missing link, named by the discoverer Pithecanthropus erec- 

 ius. The only question that seems to remain is whether it should 

 be regarded as an ape more manlike than any known ape, or a 

 man more apelike than any yet discovered. The age of this crea- 

 ture was either latest Pliocene or earliest Quaternary. 



BREAKS IN THE GEOLOGICAL RECORD AND THEIR SIGNIFICANCE. 



From the earliest times of geologic study there have been ob- 

 served unconformities of the strata and corresponding changes in 

 the fossil contents. Some of these unconformities are local and the 

 changes of organic forms inconsiderable, but sometimes they are of 

 wider extent and the changes of life system greater. In some cases 

 the unconformity is universal or nearly so, and in such cases we find 

 a complete and apparently sudden change in the fossil contents. 

 It was these universal breaks that gave rise to the belief in the 

 occurrence of violent catastrophes and corresponding wholesale 

 exterminations and re-creations of faunas and floras. 



It is evident, however, on a little reflection, that every such 

 unconformity indicates a land period at the place observed, and 

 therefore a time unrecorded in strata and fossils at that place — i. e., 



* Life and Letters of Sir Joseph Prescwich, pp. 124 tt seq. 



