6 SEA AND LAND 



have slowi)' done the work of unravelhnL;- the tangled web of 

 interlaced actions, some part of which in turn every faithful 

 observer must with the teacher's aid repeat. It is not to 

 be expected that each individual seeker for truth shall go 

 through all the laborious processes of thought which have 

 made the science which he seeks to acquire ; it is the part 

 of his guide to show him the road through the wilderness, 

 to keep him from the blintl paths which lead to no profit ; 

 but, if he would accjuire the strength which can come from his 

 personal activit)-, he must patiently tread the way himself. 



At the outset this guide may well ask the novice to have 

 in mind certain large truths of geology which may serve as a 

 background upon which he may frame the special conceptions 

 which will come to him from his shore-line studies. He may 

 be assured that all these general conceptions will be more or 

 less verified by the w^ork which he is to do. The first of these 

 concerns the contrast between the essential conditions of the 

 two orreat divisions of the earth's surface, the land of the con- 

 tinents and islands, and the water-covered areas of the sea- 

 floors. All the land above the level of the oceans which is 

 somewhat unreasonably called clr)-, for it is everywhere flowed 

 over and leached through by water, is subjected to continual 

 wearing by the action of the elements. Every rain-drop as it 

 falls and strikes ground unprotected by vegetation takes aw^ay 

 a little? of the earth. The streams bear away much — each of 

 them sends its tribute of mud, sand, or dissolved rocky mat- 

 ter to the sea ; and the ocean itself, by its unending assault 

 upon the shores, is wearing away the land along all coasts 

 save where the coral reefs build effective walls against the 

 weaves. All this water of rain-drop, spring, or stream, is sent 

 from the sea throuoh the air for the direct downward attack 



