THE gp:est covering 137 



ever evaporation is active, it is perhaps impossible to affirm that the 

 soluble alkaline earths are totally wanting from any notable amount of 

 the residuary clays. If the movement of the surface waters were wholly 

 downward through the residuar}^ layer, it would be inevitable that the 

 soluble elements of the residuary layer should be carried away from the 

 immediate surface, but it is a well known law that surface waters move 

 in various directions after they enter the ground, and that they rise as 

 well as fall. 



2. Below that thickness of the geest in which the most complete deca}^ 

 has taken place, and from which there may have been abstracted the 

 soluble elements, there is a stratum but partially decayed and but little 

 leached. In this zone the alkaline elements from above may have be-, 

 come concentrated, so that on analysis the percentage of soluble elements 

 may be greater than in the original rock. In the midst of this less de- 

 cayed zone are numerous or rare pieces of the original rock of the country, 

 more or less surrounded by a coating that has resulted from the imme- 

 diate alteration of the pebbles themselves, and in other cases such residua 

 of the solid rock can be seen to have become almost wholly converted 

 into geest, their outlines only remaining to denote their former presence 

 and their size. 



3. Finally, at the rock surface is the lowest part of the geest. Here 

 are mingled undecayed masses of the country rock along with more or 

 less wholl}' deca3^ed rock matter, and in some instances the rock itself 

 is deeply altered, so that there is a slow transition from the decayed 

 rock to the undecayed. Here are found boulders of decomposition, 

 usually not angular. 



This layer of rotted and semi-rotted rock, which sometimes reaches a 

 thickness of more than a hundred feet, has been the prey of the weather 

 during the long period of its formation. It has been subject not only to 

 the rains and the frosts, but also to the drouths and the winds, and if 

 eolian forces can produce loess, it must have been extensively formed 

 during this long period of pre-Glacial exposure. The same layer now 

 mantles the rock surface in southern latitudes. Independent of aqueous 

 agencies these southern countries should be the most noted for typical 

 and extensive deposits of loess. 



If we consider for a moment the geographic distribution of the differ- 

 ent formations that furnished the geest, some interesting inferences at 

 once become apparent. Certain characteristics of the geest are geograph- 

 ically coincident with certain formations. It would hardly be ques- 

 tioned by any geologist that the softer and younger rocks decay more 

 rapidly than the older. Hence the Tertiary and the Cretaceous would 

 disintegrate and rot more rapidly than the Carboniferous and the Car- 



