Vallei/ of Oodipoor. 67 



the rocks which we have as yet examined, are but compounds 

 of the same chemical ingredients, differing from each other in 

 their external characters according to the combinations which 

 these ingredients have formed amongst themselves. Many 

 causes may have influenced these combinations, and, among 

 others, a disturbance in the balance of affinities, induced by the 

 loss or diminution of any one of the ingredients present. Our 

 approach to any particular set of strata, is marked by a change 

 in the characters of the rocks we are leaving, and either the pre- 

 ponderance of a mineral constituent previously observed, or the 

 partial occurrence of some new combination into which the ori- 

 ginal chemical ingredients have entered, prepares us for the 

 change about to be observed. In the case before us, an ap- 

 proaching change in the particular condition of the forming 

 cause which gave origin to the quartz-rocks, is indicated by the 

 occurrence of the band of talcose schist, and the eflPects of this 

 change are observed in the talco-siliceous rocks which succeed. 

 The latter, as we proceed east, gradually assume a more grani- 

 toidal aspect. The silica, which was in the first instance dis- 

 tributed generally through the mass, assumes the form of dis- 

 tinct grains or crystals of quartz. With this felspar, also in 

 crystals, is associated ; and the mica, chlorite, talc, and other 

 constituents of the micaceous schists which follow, mark but 

 stages in the same series of changes. The connexion between 

 talc and mica is well understood, and the other mineral com- 

 pounds differ from each other not so much in their chemical 

 composition, as in the proportions which the different ingredients 

 forming them bear to one another. 



In the above enumeration, the changes alluded to have been 

 mentioned in the inverse order in which they probably occurred; 

 as we proceed westward, however, we shall perceive a similar 

 succession of changes and gradations in the rocks of the argilla- 

 ceous schist series, which now come under our consideration. 



(Tabe continued. ) 



REMARKS ON THE GYPSIES. 



There are few questions in the history of the human species 

 more curious than that of the origin and character of this singu- 

 lar people. A race of men which presents the most extraordi- 



e2 



