348 ILLOGICAL GEOLOGY. 



to enumerate them. They are admirably explained and 11 

 lustrated in Sir Charles Lyell's Principles of Geology. 



Now, if these minor rev^oliitions of the Earth's surface 

 produce minor breaks in the series of fossilized remains ; 

 must not great revolutions produce great breaks ? If a lo- 

 cal upheaval or subsidence causes throughout its small area 

 the absence of some links in the chain of. fossil forms ; does 

 it not follow that an upheaval or subsidence extending over 

 a large part of the Earth's surface, must cause the absence 

 of a great number of such links throughout a very wide 

 area ? 



When during a long epoch a continent, slowly subsiding, 

 gives place to a far-spreading ocean some miles in depth, at 

 the bottom of w^hich no deposits from rivers or abraded 

 shores can be thrown down ; and when, after some enor- 

 mous period, this ocean-bottom is gradually elevated and 

 becomes the site of new strata ; it is clear that the fossils 

 contained in these new strata are likely to have but little 

 in common wdth the fossils of the strata below them. Take, 

 in illustration, the case of the North Atlantic. We have 

 already named the fact that between this country and the 

 United States, the ocean-bottom is being covered with a 

 deposit of chalk — a deposit that has been forming, proba- 

 bly, ever since there occurred that great depression of the 

 Earth's crust from which the Atlantic resulted in remote 

 geologic times. This chalk, consists of the minute shells of 

 Foraminifera, sprinkled with remains of small Entomostra- 

 ca, and probably a few Pteropod-shells : though the sound- 

 ing lines have not yet brought up any of these last. Thus, 

 in so far as all high forms of hfe are concerned, this new 

 chalk-formation must be a blank. At rare intervals, per- 

 haps, a polar bear drifted on an iceberg, may have its bones 

 scattered over the bed ; or a dead, decaying w hale may 

 Bimilarly leave traces. But such remains must be so rare, 

 that this new chalk-formation, if visible, might be examined 



