THE PROBLEMS OF GEOLOGY 533 



are many hundreds, and the various combinations of these minerals 

 in rocks, the different phases of which are very numerous. Gas 

 without the presence of liquids and solids, liquids without the inclu- 

 sion of gases and solids, and solids which contain no gases or liquids, 

 while perhaps possible in a physical or chemical laboratory, are not 

 found in nature. As remarked by Powell, gases, liquids, and solids 

 are everywhere commingled upon the earth. All are commingled 

 with ether. Thus the various combinations of agents are beyond 

 computation. Also definite agents, for instance, water, may occur 

 in various kinds of bodies, each of which acts in a manner peculiar 

 to itself. 



The materials upon which the agents act are of the same kinds, 

 and have the same diversities and complexities, as the agents them- 

 selves. Moreover, the work done inevitably affects both the material 

 acted upon and the agent. The agent that grinds the rock-floor 

 at the bottom of a glacier is also ground. This necessity of work 

 upon both agent and substance acted upon comes under the law 

 of Newton in reference to action and reaction. The fact of work, 

 both upon agent and substance upon which the agent acts, raises 

 the question as to the distinction between the two. The answer is: 

 The agent is the substance containing energy which it expends in 

 doing work upon other substances. The substance upon which work 

 is done may thereby receive energy, and thus become an agent 

 which does work upon other substances; and so on indefinitely. 

 Indeed, the rule is that one process follows another in the sequence 

 of events, until the energy concerned becomes so dispersed as to be 

 no longer traceable. Theoretically this goes on indefinitely. 



Analysis of geological processes. We have seen that the action of 

 one or more agents through the exertion of force and the expenditure 

 of energy upon one or more substances is a geological process. It is 

 rare indeed, if it ever happens, that a single agent works through a 

 single force upon a single substance. Commonly two or more agents 

 are doing work by the expenditure of energy of various kinds at the 

 same time upon more than one material. The processes of geology, 

 therefore, vary in their complexity from the action of a single agent 

 through a single force upon a single substance, to the action .of all 

 kinds of agents through all classes of force upon the most diverse 

 combinations of substances. Thus the solution by rain-water of pure 

 calcite is a process. Also erosion, which is the work of all the agents 

 by the expenditure of various kinds of energy upon the most diverse 

 combinations of materials, is called a process. It is plain that the 

 number of processes of geology, comprising as they do all possible 

 combinations of energies, agents, and substances, are beyond number, 

 if indeed they are not infinite. If geology is to be simplified, the 

 processes must be analyzed and classified in terms of energies, agents 



