298 G. K. Gilbert — Inculcation of Scientific Method. 



In order to obtain a maximum result despite this uncertainty, I 

 have made an extreme assumption in regard to time. The 

 shore line of Lake Bonneville is in a wonderfully perfect state 

 of preservation. While one stands upon it, it is easy to be- 

 lieve that it is but a few centuries old, and the geologist, accus- 

 tomed as he is to the contemplation of eons of time, hesitates 

 to estimate its antiquity in greater units than thousands or at 

 most tens of thousands of years. When therefore we postu- 

 late its antiquity at one hundred millions of years, we pass so 

 far beyond the range of probability as to protect ourselves 

 against a possible underestimate. With these data the compu- 

 tation has been made, and it has been ascertained that a maxi- 

 mum uplift of 36 feet* can thus be accounted for. Since 

 observation shows an uplift of not less than 100 feet, the ther- 

 mal explanation is shown to be entirely inadequate ; and if we 

 were able to substitute for our imperfect data the actual data, 

 we should probably find the computed uplift too small to be 

 taken into consideration. 



If therefore we admit that the removal of the water of the 

 lake was the cause of the upheaval of the lake-bottom, there 

 seems no way to avoid the conclusion that the efficient modus 

 operandi was an upbending of the solid crust of the earth, 

 caused by hydrostatic pressure communicated through a mobile 

 substratum. But we are far from being forced to that admis- 

 sion. The coincidence in locus of the uplifted dome and the 

 Quaternary lake may have been fortuitous ; or there may even 

 have been no coincidence, for the contoured figure of deforma- 

 tion was in part supplied by the imagination; and in either of 

 these cases we can fall back on the agnostic hypothesis of un- 

 explained undulation. In the present state of observation and 

 inference the hypothesis of the hydrostatic restoration of equi- 

 librium by the underflow of heavy earth-matter is the only ex- 

 planation which explains, and none of the observed facts an- 

 tagonize it; but the alternative hypothesis is not barred out. 



To reach a satisfactory conclusion more observation is nec- 

 essary, and this discussion of the subject would be premature 

 were it not that the necessary observation is very expensive, 

 and there is no immediate prospect that it will be supplied. 

 It is fitting, however, that the desirable lines of research be 

 pointed out. 



The undertaking that promises most is an exhaustive hypso- 

 metric survey of the Bonneville shore line, including all bays 

 and islands. If this were executed, it would be possible to deduce 



* In the original paper, as read, 12 feet instead of 36 were erroneously given. 

 A friend has since pointed out that the estimate of 12 feet includes expansion in 

 the vertical direction only, whereas the coincident horizontal expansion would 

 almost necessarily be converted into uplift. 



