42 EEYIEWS — ACADIAN GEOLOGY. 



geology. The red marsh derives its color from the peroxide of iron. In the gray 

 or blue marsh, the iron exists in the state of a sulphuret, as may easily be proved 

 by exposing a piece of it to a red heat, when a strong sulphurous odour is exhaled, 

 and the red color is restored. The change is produced by the action of the animal 

 and vegetable matters present in the mud. These in their decay have a strong 

 affinity for oxygen, by virtue of which they decompose the sulphuric acid present 

 in sea water in the forni3 of sulphate of magnesia and sulphate of lime. The sul- 

 phur thus liberated enters into combination with hydrogen, obtained from the 

 organic matter or from water, and the product is sulphuretted hydrogen, the gas 

 which gives to the mud its unpleasant smell. This gas, dissolved in the water 

 which permeates the mud, enters into combination with the oxide of iron, pro- 

 ducing a sulphuret of iron, which, with the remains of the organic matter, serves 

 to color the marsh blue or gray. The sulphuret of iron remains unchanged while 

 submerged or water-soaked ; but when exposed to the atmosphere, the oxygen of 

 the air acts upon it, and it passes into sulphate of iron or green vitriol, — a sub- 

 stance poisonous to most cultivated crops, and which when dried or exposed to 

 the action of alkaline substances, deposits the hydrated brown oxide of iron. 

 Hence the bad effects of disturbing the blue marsh, and hence also the rusty color 

 of the water flowing from it. The remedies for this condition of the soil are drain- 

 ing and liming. Draining admits air and removes the saline water. Lime decom- 

 poses the sulphate of iron, and produces sulphate of lime and oxide of iron, 

 both of which are useful substances to the farmer. 



This singular and complicated series of processes, into all the details of which 

 I have not entered, is of especial interest to the geologist, as it explains the causes 

 which have produced the gray color anil abut.dance of sulphuret of iron observed 

 in many ancient rocks, which like the blue marsh have been produced from red 

 sediment, changed in color from the presence of organic matter. It also explains 

 the origin of those singular stains, which, in rocks colored by iron, so often accom- 

 pany organic remains, or testify to the former existence of those which have passed 

 away." 



In Nova Scotia, as in Canada, a wide break in the geological scale, 

 occurs below tbe drift, although of a less extensive character than 

 with us. Two formations — one of vast importance — absent in Can- 

 ada, are there met with. These are the Permian (?) and the Car- 

 boniferous formations : the latter occupying in New Brunswick and 

 Nova Scotia proper, a wide extent of territory. Devonian and, with- 

 out doubt, Silurian strata likewise occur there ; but the beds of these 

 epochs are in general much disturbed, and rendered metamorphic by 

 igneous action. From their less altered positions, however, numerous 

 fossils have been collected, some of which are figured in the present 

 work. The occurrence of still older metamorphic rocks, chiefly 

 associated with the granites of the Atlantic coast, is also shewn to 

 be exceedingly probable. 



Much doubt at one time existed as to the true age of the red sand- 

 stone strata of these regions. Sir Charles Lyell was the first to 

 prove that a considerable portion belonged to the Lower Carbonife- 



