904 GEOLOGY OF THE THIRD DISTRICT. 



CHAPTER XII. 



Of the Rocks collected for the State and for the Colleges. 



Thb collection of rocks which was made for the State Cabinet, is nearly arranged, and upon 

 a plan which affords an opportunity of becoming readily acquainted with the whole of the 

 rocks of the State, according to their mineral and especially their fossil character, and in the 

 exact order of superposition. The plan adopted was to appropriate the whole of the upper 

 part of the building to the Geological department, making a twofold division in the department, 

 reserving the whole of the lower floor for a systematic arrangement according to kind and 

 order of superposition ; keeping the gallery which surrounds the room, exclusively for a geo- 

 graphical collection, or according to the counties ; so that the local, the economic interest, as 

 well as original products, and those which were the result of decomposition or alteration of 

 original products, should be placed together, being the only way to prevent that confusion 

 which is produced in the mind when all are in juxtaposition. The first floor is reserved for 

 the great masses of original products, in their order of succession, the object of which is to 

 make known the history of the earth by the products which have followed each other in regu- 

 lar sequence. The arrangements on the first are nearly completed, wanting a few more tables. 

 Those of the gallery are not commenced, excepting temporarily by Mr. Mather ; but enough 

 there will be done, to show the utility of that reservation, or the collection which vrill there be 

 exhibited. 



The plan of arrangement upon the lower floor, consists in having a Table with a glass cover 

 for each rock, group or geological element, with the name in large printed letters on the front 

 side of the table ; having nothing within each table but what was known with certainty to 

 belong to it as an original product, each product having a place, and each product in its place. 

 The tables, as they represent a rock or group, are arranged around the room, at some distance 

 from the walls, in the form of a parallelogram, and in the order of their succession, com- 

 mencing with the primary, placed near the door at the left hand, the order being from left to 

 right. Thus, in a few hours the examiner is carried from a table which contains the rocks 

 of the Primary system, to the one which holds those of the Catskill group ; at the right of 

 which is another table, containing a suite of the Coal rocks of Pennsylvania, placed merely 

 for those unacquainted with them, that they might have an opportunity of at once observing 

 the difference between them and all those rocks below, or to the left hand, which form the 



