130 MIDDLEMISS: PHYSICAL GEOLOGY OF SUB-HIMALAYA. 



connection, for every writer who puts forward a world-wide hypothesis 

 of this kind should, and no doubt does, expect it to be confirmed or 

 refuted by different labourers in their own fields. 



The subject is of course a little discursive, and must lead one to 

 consider principles as well as facts, and to touch on evidence derived 

 from other countries. Let us then turn to a recent book, "The 

 Origin of Mountain Ranges," by Mr. T. Mellard Reade, and see whether 

 the structure of the Sub-Himalaya as interpreted in the foregoing 

 pages of this memoir is in agreement or otherwise with that author's 

 conclusions. 



Fortunately for the critic who has not unlimited space at his 

 Considerations of Mr. disposal the fundamental doctrine of "The 

 Mellard Reade's theory. Origin of Mountain Ranges " is easy to com- 

 prehend and tersely expressed ; though unfortunately the argument 

 is also terse, whilst the bulk of the book is taken up with descrip- 

 tions and illustrations from many of the mountainous regions of 

 the earth, which seem to me to be only sometimes relevant to the 

 theories propounded, and with laboratory experiments, which I think 

 are too artificial to be taken seriously as working models of the crust 

 of the earth. With reference to the latter it is manifestly impossible 

 to produce with the means at our disposal the condition of rocks at 

 great depths and under the enormous pressure to which they must 

 be subjected. Matter there must be in a state of which we have no 

 experience, and attempts at imitation can at the best be but carica- 

 tures. 



The key-note of Mr. Mellard Reade's book is that mountainous 

 regions have been areas of great sedimentation, both vertical and 

 horizontal — a sedimentation which is supposed to have raised the 

 isogeotherms among the mass of those sedimentaries, thereby pro- 

 ducing expansion by the increased heat. Thus it comes to pass 

 that great sedimentation is the forerunner of upheaval, and also a 

 factor in the cause of it. It must be noted here that the author 

 gives no proof that sedimentation raises the isogeotherms, but merely 

 states that " in 1834 Babbage .... pointed out that the addition of 

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