68 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



upon the present shores, (-)r the newly made land may have been 

 covei'ed with gravel or shells. Any of these agencies would have 

 been sufficient. In the case of the ripple-markings, these slight fur- 

 rows may have been uneven ; a larger one than its neighboui'S 

 attracting the drops of water falling upon the surface of the rock, 

 either in the shape of lain o)' as spray from the ocean, or it may he 

 the receding tidal waters of the sea : A little channel is formed, this 

 draws other little rills to it, and in this way it goes along growing 

 in size as it incieases in length. This operation can be seen any and 

 every day upon the sea shore wherever there may be a deposit of sand 

 or clay. Eveiy stage of tlie work passes before the observer's eye 

 during the few hours the tide is absent — the wave-furrows, the trick- 

 ling of the water along the funow, its gathering in size and finally its 

 miniature gorge where it ])asses tli rough the bank of mud into, the 

 ocean. The land rises a little and fresh beds are laid bare. The 

 streamlet becomes longer and deeper ; its branches increase in size and 

 number and its drainage area gi'ows greatei-. So the work goes on, 

 the land rising, the stream becoming greater and stronger as its course 

 lengthens until by successive elevations the land has become a conti- 

 nent in extent, and the stream a river hundreds of miles in length, 

 gigantic in depth and width, and the small channels which joined it 

 away back in the past ages are now mighty lateral gorges, or it may 

 be that the whole system has broadened out into extensive valley 

 plains, the site of cosy fai-m-houses or occupied by a populous city, 

 while the tiny wave marking has become a gi-eat commercial high- 

 way for the nations of the woi'ld. 



It was in some such simple manner as this that the Grand Canon 

 and other similar gorges found in Colorado, in what is known as 

 the Grand Canon District, described by Dutton, were formed. They 

 are not due to any great convulsion of the earth, such as earthquakes 

 or volcanic eruption, but are solely the effects of quiet persistent never 

 ceasing erosion. The livers running through these Canons were 

 formed when the Tertiary rocks first rose above the sea level. Some 

 irregulai-ity of the surface then determined their course and ever since 

 that time they have kept persistently in that course until now the 

 Grand River has cut a gorge 5,000 feet deep, straight down into the 

 carboniferous formations. The rocks rose up in front of the river and 

 ■were cut through. 



