306 H. O. WOOD SOME CONSIDERATIONS TOUCHING ON ISOSTASY 



the factor of time in this behavior, and of the acceleration of such yield- 

 ing under moderately elevated temperatures. 



Thus the geologist, though convinced that the outermost shell of the 

 earth is very strong in respect to certain conditions of stress, finds his own 

 observations confusing in some ways, as well as the facts and principles 

 of physics to which he must appeal. He has few measurements — perhaps 

 none — which approach in precision those utilized in the geodetic discus- 

 sion. From a standpoint of debate he occupies a weak position in put- 

 ting forward an opinion or, better, a judgment supported by qualitative 

 and in some respects mutually contradictory observations in opposition 

 to a judgment reposing on sound measurements treated in a probably 

 legitimate way. Fortunately, mere debate has no place in scientific 

 inquiry. 



Difficulties of geologic Interpretation 



A figure of speech may here serve a useful purpose. In the chronicle 

 of the earth geodesists have read off — may we say glibly? — a single sen- 

 tence or phrase recently written and undefaced, while geologists must 

 patiently decipher innumerable fragmentary letters, words, and phrases 

 found here and there in the tattered pages of a book of encyclopedic 

 dimensions scarcely a line of which has escaped mutilation. By far the 

 greater part of this book has been destroyed during the writing of it, and 

 of what remains only a small portion has been deciphered and interpreted, 

 some of it erroneously, without doubt. Nevertheless, since no one geol- 

 ogist can personally examine more than a very small fraction of the frag- 

 mentary remains, he must accept, for the rest, the readings of his col- 

 leagues. Small wonder that there is a diversity of interpretation and 

 opinion; that even a single worker may happen upon phrases which seem 

 to stand in conflict. Notwithstanding all this, there has come to be a 

 consensus of opinion in many matters that have seemed clear and con- 

 sistent which would appear to become uncertain and of doubtful consist- 

 ency if they must be brought into strict accord with tha meaning ex- 

 pressed in the single undefaced phrase pointed to by geodesists. The 

 geologist is thus in something of a dilemma. Must he review and recon- 

 struct his whole philosophy of earth dynamics, or, to shift the figure, is 

 it possible that the geodesist, in pursuing a straight and level short cut 

 to his destination, has missed a good part of the scenery? Granting the 

 geodetic facts, must these be accepted and interpreted narrowly, or are 

 there alternative ways to utilize them? About all this whole books must 

 yet be written. It is not easy to select a few clear, vital principles to 

 illumine a brief discussion; but it is sure, nevertheless, that geologists 



