346 Prof. Keilhau on the Present State of Geology. 



The constructive character which predominates in much too 

 high a degree in the present method, can be limited to a great 

 extent. It is possible to observe with much greater accuracy 

 and certainty than has hitherto generally been done, and in 

 this way to procure attention even for facts which cannot at 

 once be explained so as to harmonize with the results obtained 

 from other sciences, but which must nevertheless be studied 

 in order to advance the science. It is possible to procure 

 for geological facts more than they have hitherto possessed 

 of the influence to which they are entitled, in the explana- 

 tion of many of the most important problems of which the 

 only solutions hitherto attempted have been derived from 

 sources foreign to geology. It is possible, especially, to em- 

 ploy the assistance of chemistry in geology in a more judicious 

 manner than heretofore. 



There are, indeed, not a few mountain-rocks which, either 

 themselves, or their complete analogues, are formed before our 

 eyes by processes whose general nature cannot admit of a 

 doubt. A multitude of other mineral masses, however, and, 

 among them, precisely those which play the most important 

 part in the structure of the earth, viz. the greater part of the 

 crystalline rocks, have an entirely hidden origin and develop- 

 ment. The direct observation of the mode of formation of 

 these is so difficult, that it has not yet been definitively deter- 

 mined (for I must be allowed this assertion) to which principal 

 class the agent belongs that has here specially been in opera- 

 tion. It is more particularly with regard to these mountain 

 rocks that the method of investigation hitherto pursued must 

 be changed in the manner already indicated. More diligence 

 must here be employed than has hitherto been bestowed in 

 the discovery of all the geognostical relations presented by 

 these rocks ; and, at the same time, in the decision of debate- 

 able subjects, greater influence must be given than heretofore 

 to the results obtained by means of unprejudiced observation. 

 It is especially requisite to beware of the principle, that che- 

 mistry alone can and must decide in such matters ; for, although 

 the laying down of this maxim as a fundamental truth has 

 been behoved to be the perfectly philosophical mode of going 

 to work, it may nevertheless turn out to be incorrect Inas- 



