DEFORMATION OF ROCKS Ae 
order; upon these are waves of the third order, and on these 
waves of the fourth order, and so on. Moreover, running across 
the most conspicuous waves at various angles up to perpendicu- 
larity may be other waves of an equally composite character. 
As observed from a ship at sea the waves of the first order are 
so large and have such gentle slopes that they are often over- 
looked, while the steeper waves of the second order are noticed, 
because more conspicuous. On account of their small size 
the waves of a higher order than the second are usually unno- 
ticed, as are also the waves of all orders which are transverse to 
the more conspicuous set. 
If when stirred by a great storm the surface of the sea could 
in an instant be frozen, we should obtain some idea of the com- 
plexity of the waves. We should see primary elevations and 
depressions of circular, oval, and lenticular horizontal sections, 
in different sets, crossing One another in various directions, and 
upon these would be other sets of waves of like complexity of 
the second, third, and fourth orders, and so on. 
The rock waves of the earth are of greater size and of equal 
or greater complexity than the waves of the sea. The rollers of 
the sea, when not wind forced may be compared with the long, 
gentle folds of rock. At first sight they seem simple, but, like 
the rock folds, when observed closely they are found to possess 
secondary crenulations. At the other extreme are the highly 
complex waves running in various directions at the same time, 
formed by the shifting winds of a great storm, by currents and 
tides together. The sea in this condition may be compared with 
the rocks in which each set of primary folds has superimposed 
upon them folds of the second order, and upon these those of a 
higher order to the mth order. The smaller orders of folds are 
microscopic. Such complex rock folds are called crumpled, 
plicated, or implicated. 
In this comparison it is not meant to imply that the forces 
which produce rock folds are the same, or that they work in the 
same manner, as the forces which produce sea waves. Nor is it 
meant that the forms of the folds are the same as the forms of 
