92 Dr. Dawson on the Flora 



of the Falls of Niagara, or by the growth of the alluvial plain of 

 the Mississippi ; or with Agassiz, by the extension of the Peninsula 

 of Florida, or endeavour to estimate the time required for the 

 abrasion and deposition of the great mass of clay that fills the 

 valley of the St. Lawrence, we cannot suppose that less than two or 

 three hundred centuries have elapsed since the alpine plants of 

 the White Mountains were cut off from all connection with their 

 Arctic relatives. Their reign upon the mountain tops not only 

 antedates all human dynasties, but reaches far beyond the creation 

 of man himself and many of his contemporaries. 



Positive evidence of the existence of some of these plants dur- 

 ing a large portion of this lapse of time, has actually been pre- 

 served in the Post-phocene deposits of Canada. At Green's 

 Creek on the Ottawa, in nodules in the clay containing marine 

 shells, and coeval with the Leda clay of Montreal, there are 

 numerous remains of plants that have been embedded in this 

 clay at a time when the Ottawa valley was a bay or estuary, and 

 when the Adirondack Mountains of New York and the moun- 

 tains of New England were two rocky islands separated from each 

 other, and from the mainland on the north, by wide arms of the 

 sea. The plants found in these nodules all appear to be of mo- 

 dern species. It is of course not easy to recognise the specific 

 characters in these fragments, but I think I have good evidence 

 of Potentilla Norvegica^ P. tridentata, and possibly P. Canadensis; 

 Populus balsamifera, Arctostaphylos uva-ursi, Trifolium repenSy 

 Drosera rotundifolia, Potamogeton natans, and P. perfoliatum.* 

 There are also seeds apparently of ranunculaceous plants ; grasses 

 and carices, and mosses. Several of these plants are found on 

 the White Mountains, and they are all northern and arctic species. 

 I have no doubt that further examination of these deposits will 

 lead to the discovery of additional examples. This fact, proving 

 as it does the existence of these species at the period in which 

 the theory of Lyell and Forbes requires them to have migrated,, 

 is in itself strong corroborative evidence. We can say that some 

 of these species were waiting on the shores of the north, ready to 

 be drifted to the insular spots to the south-west, and that their 

 seeds were actually being washed out to sea by the streams which 

 emptied themselves into the then estuary of the Ottawa. 



* These determinations were made from specimens in the collection 

 of the Geological Survey, and from others kindly collected for me by 



