PALEONTOLOGICAL BEEAKS. 193 



ist. This may be true in a limited number of cases ; but there is 

 every reason to believe that the constancy of breaks is even far 

 greater than the most enthusiastic advocate of the doctrine of im- 

 perfection would be ready to admit. For, even in such areas where 

 the rock-masses through a general uniformity of character would 

 seem to indicate continuous sedimentation, have we always definite 

 proof that the sedimentation was really continuous ? Par from it. 

 If, for example, certain parts of the Atlantic border of the United 

 States were depressed beneath the sea, and a new Post-Tertiary 

 deposit imposed upon them, we might be not a particle the wiser, 

 as far as stratigraphical and lithological evidence went to show, for 

 the enormous period of time that intervened between the formation 

 of the newest and next newest (Miocene) series of deposits. The 

 strata would lie practically conformably on one another, and it would 

 require but little degradation to plane down these inequalities, 

 which would otherwise indicate an eroded land surface. The mem- 

 bers of the Cretaceo-Bocene series of the State of New Jersey, and 

 elsewhere along the same coast, are so intimately related to one an- 

 other, by conformability of position and lithological structure, that 

 it might readily have been assumed that we had here an instance of 

 continuous sedimentation ; and, indeed, for a long time no division- 

 line was supposed to exist. But the unmistakable evidence of pale- 

 ontology proves that here, as well as at most parts of the earth's 

 surface which have been made accessible to the geologist, a break 

 marks the junction of the Cretaceous and Tertiary formations. 



It must be admitted that there are certain anomalies connected 

 with the occurrence of breaks which have not thus far received an 

 adequate explanation. Their broad distribution — ^it might, indeed, 

 almost be said universality — in equivalent periods of time, has long 

 been noted as a surprising fact, and one that still remains in the 

 nature of a puzzle to the geologist. Nowhere on the surface of the 

 earth has there as yet been found a distinct connection between the 

 Paleozoic and Mesozoic series of deposits, and only at a very few 

 points (India, New Zealand, California) what may be considered to 

 be an unequivocal link between the Mesozoic and Cainozoic series 

 (Cretaceous and Tertiary). It is true that the field surveyed by the 

 geologist is of comparatively limited extent, when compared with 

 that which still remains to be explored — the greater part of the conti- 

 nents of Asia, Africa, South America, and Australia — and it is but 

 U 



