TIME AND LIFE 133 



The reefs of the Pacific, the deep-sea soundings of the 

 Atlantic, show that it is to the slow-growing coral and 

 to the imperceptible animalcule, which lives its brief space 

 and then adds its tiny shell to the muddy cairn left by its 

 brethren and ancestors, that we must look as the agents in 

 the formation of limestone and chalk, and not to hypotheti- 

 cal oceans saturated with calcareous salts and suddenly 

 depositing them. 



And while the inquirer has thus learnt that existing 

 forces give them time are competent to produce all the 

 physical phenomena we meet with in the rocks, so, on the 

 other side, the study of the marks left in the ancient strata 

 by past physical actions shows that these were similar to 

 those which now obtain. Ancient beaches are met with 

 whose pebbles are like those found on modern shores ; the 

 hardened sea-sands of the oldest epochs show ripple-marks, 

 such as may now be found on every sandy coast ; nay, 

 more, the pits left by ancient rain-drops prove that even 

 in the very earliest ages, the " bow in the clouds " must 

 have adorned the palaeozoic firmament. So that if we 

 could reverse the legend of the Seven Sleepers, if we 

 could sleep back through the past, and awake a million 

 ages before our own epoch, in the midst of the earliest 

 geologic times, there is no reason to believe that sea, or 

 sky, or the aspect of the land would warn us of the marvellous 

 retrospection. 



Such are the beliefs which modern physical geologists 

 hold, or, at any rate, tend towards holding. But, in so 

 doing, it is obvious that they by no means prejudge the 

 question, as to what the physical condition of the globe 

 may have been before our chapters of its history begin, 

 in what may be called (with that licence which is implied 

 in the often-used term " prehistoric epoch ") " pregeologic 

 time." The views indicated, in fact, are not only quite 

 consistent with the hypothesis, that, in the still earlier 

 period referred to, the condition of our world was very 

 different ; but they may be held by some to necessitate 

 that hypothesis. The physical philosopher who is accu- 

 rately acquainted with the velocity of a cannon-ball, and 

 the precise character of the line which it traverses for a 

 yard of its course, is necessitated by what he knows of 

 the laws of nature to conclude that it came from a certain 

 spot, whence it was impelled by a certain force, and that 

 it has followed a certain trajectory. In like manner, the 



