No. 3.] SPENCER PALAEOZOIC GEOLOGY. 151 



centa2;e of clay, free sand and silicates of the nlkaline earths. 

 Sometimes, however, there is an excess of carbonate of lime over 

 what is required for the producrion of the double carbonate. 

 Under the microscope this excess of calcite is seen occupying the 

 small spaces between tlie more uniibrmly crystalline particles of 

 dolomite. The quantity of iron is generally small, and present 

 in the state of protoxide, though in some of the beds it occurs as 

 pyrites. Bituminous coloring matter is present in many of the 

 strata, and in a number of beds it occasionally fills small cavities. 

 There are but few beds east of Dundas which have not a con- 

 siderable quantity of earthy matter present. 



The shales in this region differ from limestones only in the larger 

 quantity of clay and other silicates present in place of the calca- 

 reous matter, for they all contain a large percentage of carbonate. 

 In fact many of the beds are of an intermediate character, that 

 it is difficult to decide whether to call them earthy limestones or 

 calcareous shales. Of several beds at Hamilton. I made the 

 chemical analyses, together with a microscopic examination. A 

 few of the results are here iriven. 



Anali/sis J. — The sample was taken from near the base of 

 the series (No. 7 of section) at the -'Jolly Cut," Hamilton. 

 Under the microscope only a mass of transparent particles of 



dolomite, separated by dark amorphous earthy matter, was 



visible. 



Calcium carhonate 4G-6 



Magnesium carhonate 36-5 



Ferrous carbonate ] -7 



Calcium silicate -^ 



Magnesium silicate / ' ^ 



Alumina 4-4 



Silica 6-7 



Moisture (i-H 



99-8 



c 



Anali/.sis II. — This analysis represents the composition of the 

 thick bed of light gray dolomite (No. 8 of section) at the "Jolly 

 Cut," Hamilton. The rock is liighly crystalline, and shows 

 crystalline plates of criuoids and shells, but seldom contains 

 complete casts of fossils. Under the microscope it shows a mass 

 of crystalline semi-transparent particles of dolomite, full of small 

 cavities, which are often lined or filled with pure calcite, conse- 

 quently the carbonate of lime is in excess. This bed contains 



