'-.'7 1 ANALYSES OF SOILS. 



therefore do not exist originally in the organic matter, but are a result brought about by 

 tbf processes i>> which they have been subjected. 



The rooks under consideration are usually concealed by s great amount of their own 

 debris. It is therefore impossible to determine their thickness or their extent ; the] ore, 

 however, between one hundred and fifty and two hundred feet thick. 



We have already stated that the shales contain beds of gypsum. The Lowest bcd> are 

 merely thin inconsiderable masses, unfit or unprofitable for working; yel the amount of 

 er is considerable. The rock itself, with its plaster, would form a very valuable 

 manure in many parts of the State. The decomposing shales, when plaster is wanting, 

 may be regarded as valuable as gypsum, and perhaps more bo ; they have not, however, 

 been employed, and hence have not received the sanction of experiment or trial. 



In addition to the plaster beds, the Bhales embrace a singular deposit, which was called 

 by Mr. Eaton vermicular limerock. This deposit, however, is not entitled to a distinct 

 name, inasmuch as it is subordinate to the shales, and forms but an inconsiderable mass 

 in the group. The vermicular rock is an impure limestone, and is composed of the fol- 

 lowing elements : 



Water 0-23 



Organic matter 2-54 



Silex 3-30 



Carbonic acid 20-62 



Alumina 5*33 



Magnesia 4-26 



Carbonate of lime 13 '76 



Protoxide of iron a trace. 



50-04 in 50 parts. 



The main deposit of plaster is above those porous strata, the composition of which 

 has been furnished in the preceding pages. 



The soft green shales pass into thin-bedded limestones, quite compact and hard, and 

 which, on being struck, emit a sharp ringing sound similar to clinkstone. These thin beds 

 contain the hydraulic limestones, which have been described. 



These parts of the series differ considerably in composition from those below. According 

 to Dr. Beck, tleir composition (the water-limes) is as follows : 



Carbonic acid 39-80 



Lime 25-24 



uesia 18-80 



Silica and alumina 13-50 



Peroxide of iron 1-25 



Moisture and loss 1-41 



100 -00 



