226 The Physical History of the Trias 



time when these beds were accumulating, it is necessary, in 

 accordance with the uniformitarian principle of geology, to 

 make ourselves familiar with some region where similar sedi- 

 ments are forming at the present day. 



Perhaps the very best locality that can be selected for such 

 an examination is the Bay of Fundy. It has been my good 

 fortune to spend a number of weeks on the shores of this 

 interesting bay, during which time I learned many important 

 facts which have been of value to me in studying the Trias. 



If we approach the shore of the Bay of Fundy at high tide, 

 we behold a broad expanse of rolling, intensely turbid waters, 

 which fill all the creeks and inlets along the shore and come 

 up to the verdure at our feet. If we return to the same scene 

 at low water, especially if our visit is to some of the upper 

 reaches of the bay, we see, instead of the turbid waters, a wide 

 area of smooth glossy mud, extending far out from the shore, with 

 a diminutive stream of muddy water flowing through the centre. 

 During a warm day this exposed mud-flat sometimes becomes 

 dried and cracked by the sun ; or a passing shower will pit 

 many acres of its surface with rain-drop impressions. The 

 retreating waters frequently leave the expanse of mud covered 

 with beautiful ripple-marks, from the nature of which we can 

 sometimes judge of the character of the weather when they 

 were produced. These same mud-flats are also trodden by 

 large numbers of aquatic and shore-loving birds, and not 

 unfrequently impressed by the feet of men and animals. 

 When the next tide comes rushing in, sometimes with an eagre 

 or bore, much of this surface which had not become 

 sufficiently hardened, is torn up and washed away ; but other 

 portions, inscribed with all these records of surrounding con- 

 ditions and of animal life, are covered with another layer of 

 tenaceous mud, which in its turn is left exposed by the next 

 retreat of the tide, with a smooth or ripple-marked surface 

 ready to receive the records of another series of daily 

 changes. Such, in brief, is the character of the accumulation 

 of mud and sand, now forming on the shores of the Bay of 



