ANNIVERSARY ADDRESS OF THE TUESIDENT. XXXlll 



the angular motion amounting to one degree, and therefore scarcely 

 perceptible, — Anglesea would be sunk 20,000 feet below the level 

 of the sea : and he proceeds to observe how far more probable such 

 movements are, than that which lifts whole continental masses in an 

 exactly vertical direction. 



In his remarks on the colouring-matter of red sandstones and of 

 greyish and white beds associated with them, Mr. Dawson describes 

 the accumulations of Nova Scotia forming the lower part of the car- 

 boniferous system of that country, showing the manner in which the 

 peroxide of iron, which forms the red colour of many of the beds, is 

 diffused through the mass of the clays and shales, mingles with the 

 cementing matter of the sandstones, and stains the surfaces of the 

 pebbles. He also points to the admixture of these red beds with the 

 other kinds of strata not so coloured, such as dark grey sandstones 

 and shales, some beds with scarcely any ferruginous matter, others 

 with small quantities of carbonate and sulphuret of iron. A consi- 

 derable thickness of these dark beds contains fossil plants, bituminous 

 matter, or thin seams of coal. He also mentions limestones and gyp- 

 sum. Mr. Dawson supposes the peroxide of iron of the red beds to 

 have been mainly derived from the decomposition of the iron pyrites 

 contained in the Silurian and metamorphic rocks ; and thinks that 

 the sulphuric acid which may have been formed might have united 

 with calcareous matter accumulated by molluscs and corals and have 

 formed gypsum, and that decomposing vegetable matter prevented 

 the iron from remaining as the peroxide in beds associated with the 

 red beds, and not of a red colour. 



The cause of the wide distribution of red beds of clays, shales, sand- 

 stones and conglomerates, occurring as they do of all geological ages, 

 from the lowest to the highest sedimentary deposits, is one of much 

 interest. We find these beds most frequently intermingled with strata 

 of bluish green, greenish, and grey tints, some even quite colourless. 

 Upon carefully examining many of these deposits we see that some- 

 times the different tints were original, the drift having been mingled 

 with peroxide of iron at one time and not at another ; and again we 

 obserA'e effects which, as you are well aware, have of late years been 

 attributed to the action of decomposing organic substances upon the 

 peroxide of iron, in the manner adverted to by Mr. Dawson, so as to 

 convert the peroxide into a protoxide, carbonic acid being formed 

 partly at the expense of the peroxide of iron. 



Palceontology. 



In his remarks on the internal structure of Halonia, Mr. Dawes 

 considers that this fossil plant should be referred to the vascular 

 Cryptogamise, and that when compared with the plants found in the 

 coal-measures, its nearest affinity is to the Lepidodendron. He 

 points out '* that a narrow ring of very regular, compact, elongated 

 tissue exists on the outer portion of the cortical zone, similar to the 

 prosenchymatous arrangement mentioned as occurring in the corre- 

 sponding part of the Lepidodendron." He also remarks that " the 

 medullary column does not, either in the Lepidodendron or the Ha- 



VOL. V. — PART I. C 



