Correspondence. 85 



strata they present no trace of this structure ; yet no one would 

 think of calling them sandstones or quartzites. In their original 

 state I can imagine them described as very light, friable clays. The 

 literature of transition rocks {e.g. Professor Eamsay's recent Memoir 

 on North Wales) may be consulted with the same effect as the 

 Survey collections. In this field of observation practice seems unani- 

 mous upon the necessity of a class-name for the rock in question, 

 and upon the appropriateness of the word grit. 



On the other side of the argument are to be found all text-books, 

 glossaries, and lectures. It is indeed probable, that if an impromptu 

 show of hands could be called for, the geologists of England would 

 agree that a grit is a coarse, sharp sandstone — an essentially different 

 rock in all its characters and associations from that before described. 

 It is not difScidt to explain such an anomaly — nine-tenths of our 

 geologists have done little or no work upon transition rocks ; so that 

 the occasion for the ambiguous use of the term has never occurred to 

 them ; the remaining minority could not, all of a sudden, revoke a 

 familiar expression. I have yearly to fight this battle of the grits 

 with new assistants joining the Indian Survey, and seldom with any 

 good result. Naturally enough, with all the enthusiasm of youth for 

 the respected teachers of the schools, they prefer the recent lessons 

 of those high authorities to the representations of an obscure Indian ; 

 and, to my great discomfiture, the oral and printed instructions of 

 those to whose field-practice I vainly appeal, are most frequently 

 quoted against me. The unfortunate result is, that this broad dis- 

 crepancy in our vocabulary is perpetuated in the annals of our work : 

 those who are set to map and describe the Coal-deposits find this 

 grit a very handy term, and use it triumphantly. It is with the 

 conviction that my respected old masters, who know both sides of 

 the question, will be more reasonable than their more recent pupils, 

 and will at least drop one or other signification, that I venture to 

 send home this appeal to them and to their judges, the geological 

 public. 



To aid in the decision I call for, I will add my own notions on 

 the point at issue. The word grit was, I believe, introduced to us 

 through the Millstone-grit, from a technological vocabulary in which 

 we should find it applied as appropriately to a cellular trachyte as 

 to a sandstone. By a true process of natural solution, it seems to 

 have been applied to the rock I first described — to fill a real gap in 

 our geological vocabulary. If this latter application of the word be 

 abandoned, some new word must be coined or borrowed to take its 

 place ; whereas no such plea can be urged for the continual use of 

 the word as applied to sandstone — there could be no difficulty in 

 describing our Indian Coal-measures without a special name for one 

 of the many varieties of sandstone that occur. Convenience should not 

 be the umpire in such matters. Such a practice is unsystematic and 

 confusing. "What would a naturalist say to the phrase — a collection 

 of dogs and quadrupeds? To me, the words "a series of grits and 

 sandstones " sounds just as barbarous, when I know that the first 

 word only means a common sandstone. If, in geology, we can as 



