THE UNA WEEP CANON. 



781 



The work, of which we have given a brief summary, " Recherches 

 sur les Graines Fossiles Silicifiees," consists of twenty-one plates, giv- 

 ing accurate and exactly colored representations of the seeds examined, 

 with careful explanations. The comj>letion of the text was interrupted 



Fig. 3. Pabt of the Preceding Figure, magnified Ten TimE8. 



by the death of the author, but the plates are finished, the details in 

 them that were left lacking having been supplied by M. Renault, after 

 comparison with the identical specimens. The whole work, in its 

 present form, constitutes a real monument erected by pious hands to 

 the memory of the illustrious founder of the science of fossil botany. 



THE UNAWEEP CANON. 



By HENRY GANNETT. 



OF all the physical features of the earth, the courses of rivers are 

 among the most unchangeable. Once outlined, they are adhered 

 to with a wonderful tenacity. Only a general change in the slope of 

 their basins will usually suffice to divert them from their original 

 courses. Mountains and plateaus may rise across their paths, but, like 

 a saw, the river cuts its way through the obstacle. It is very rare 

 to find a case where a river has been diverted from its course by the 

 rising of a mountain-range or other minor elevation across it, while 

 numberless instances of rivers having overcome such obstacles are to 

 be seen in all mountainous regions. The Cordilleran region of the 

 West presents us with many such examples. Many are familiar with 

 the gorge by which Green River passes the Uintah range, in Wyoming 



