47 



" On further observation we discovered a constant njovenient of 

 exceedingly fine sand dust caused by the gentlest zephyrs. While 

 descending we noticed several places where the sand was actually trick- 

 ling down the crevices. Streams of sand, varying and spasmodically 

 fluctuating, were constantly lessening the mass above and filling the 

 hollows below. 



" So far we have said but little concerning the cause of sand forma- 

 tion or rather rock wearing during summer weather. At any time 

 during the warm summer months fine sand dust may be discerned even 

 on clean-looking boulders by means of a small magnifier. 



*' The weather-beaten exterior of all rocks is more or less cracked 

 and granulated. Numberless fine ci-acks ramify in all pos-sible direc- 

 tions. Many of these are invisible to the naked eye. When the rain 

 falls the water saturates the sui-face. After a little while the tempera- 

 ture rises. The expansion of the moisture in the cracks pries off many 

 small grains of sand. In fact we are safe in saying that during the 

 months of warm weather the contraction of the rock surface in the 

 night, and the expansion consequent upon the heat of the following 

 day, without any reference to dampness, wears away the rocks con- 

 stantly." 



When we remember that this section of the valley utider consider- 

 ation belongs to the oldest of all geological periods our interest must 

 increase. Geologists have marked out over thirty geological divisions. 

 Here, however, there is one, the oldest, the Archaean, of which Dana 

 says : "■ There was first an age or division of time when there was no 

 life on the globe ; or if any existed this was true only in the later part 

 of the age, and the life was probably of the very simplest kinds. The 

 Archaean stands apart as preparatory to the age of invertebrates." 

 Now in saying that this district belongs to only one geological period 

 we do not mean that there has been no change during the many ages of 

 the past. But we do mean that the rocks are Archaean with a base 

 surrounding of their own refuse and ruins. Some would prefer to say 

 that the first and last geological periods meet in this valley. Here the 

 Aozoic stanas ont in majestic sublimity, looking down upon the only 

 child of its many years. This could be called the Quaternary period, 

 and, Minerva like, came from the head rather than the loins of its pro- 



