150 



NOTES ON THE GEOLOGY OF TORONTO. 



[1853 



an opportunity of obtaining. First then, with respect to the re- 

 mains of an ancient vegetation. Tlie Blue Shales contain many 

 fragments, and sometimes entire specimens of Marine plants. 

 Few of them are of comparatively large dimensions, ha.ing a 

 diameter of perhaps an inch. Most of the specimens before you 

 are crushed ; their original form hn\ing been cylindrical, 

 as we see from nunwroiis examples. It is a matter of consideia- 

 ble difficulty to refer, with accuracy, ditl'erent specimens to their 

 appropriate described species. The varieties I have met with are 

 SIX or seven in number; but whether they all belong to as many 

 ditFerent specie=, is a question I am unable to answer. At 

 certain periods vegetable growth must have been most abundant, 

 during the remote epoch of the Loraine Shales, fragments occur 

 in particular layere in immense numbers. Coi-als are numerous 

 in both the Sandstones and Shales of the cliff. Masses of the 

 rock appear to be almost entirely made up of their calcareous 

 remains. Some of the specimens are beautifully marked, a mag- 

 nifying glass, however, is required to bring out their markings. 



All of these little spheroidial bodies are corals, and exhibit 

 ■when broken that peculiar organized structure which distinguishes 

 them at once tVom similar objects. Some of them are several 

 inches in diameter, and are covered with a shining substance, 

 ■which proves, upon examination, to be sulphuret of iron. On 

 breaking open one of these little round nodules, its history in 

 part, and its mode of growth, is at once observable. In the 

 centre we see a cylindrical stem possessing, apparently, a num- 

 ber of joints, it is a stem of an encrenite, of which the celebrated 

 stone lilies are the most familiar illustrations. Round this stem 

 the little coral has grown. Most of the white objects ■«-hich are 

 so frequently visible in large numbere at the surface of the lake 

 stone a few inches below the ■water, are corals worn and polished 

 by the action of the waves. The forms assumed by this species 

 of coral (Chetetes Lycoperdon) are very numerous, it frequently 

 occui-s as a branched variety bearing no resemblance except in 

 organization to these round specimens. One peculiarity connected 

 with the rocks at the Garrison Common cannot escape the most 

 superficial observer. It is the occurrence of layers containing 

 multitudes of corals and the stems of encrenites, while a few inches 

 above them or below them other layers enclosing an equal 

 abundance of vegetable remains — fucoids — are prominently dis- 

 played. These circumstances indicate probably, very different 

 conditions of the sea in which they grew, and a peculiar adapta- 

 tion of the separate deposits for the growth of different kinds of 

 oi'ganized forms. The layer of shale I hold in my hand, shows 

 in as admirably manner, though on a small scale, the commence- 

 ment and duration of a period favourable to the growth of 

 encrenites and corals. Its lowest side shows only a series of 

 regular lamina; without any fossils. The upper half is a mass of 

 fragments of encrenites and the branched form of the common 

 coral before mentioned. Here, however, ■we have a far more 

 beautiful indication of the condition of the Silurian sea during 

 the deposition of the ripple marked shale ■svhich answers to the 

 number fifteen in the diagram of the strata. These ripple marks 

 penetrate the stone to a considerable depth, as may be seen by 

 splitting the specimen. 



We seem here to have the distinct and permanent record of 

 a gentle ripple on the beach of a shallow sea countless ages ago. 

 We may even attempt to form a conjecture of the direction in 

 which the wind blew, which disturbed the surface of the water 

 in those remote times. If we suppose that the Loraine Shales 

 here exposed, have received no lateral change in ]iosition, and I 

 am not aware of any reason for conceiving such change to have 

 taken place, the direction of the ripple mark.*, shows the direc- 

 tion of the motion of the little waves which rolled upon a gentle 

 beach, and consequently detennines the point from which the 

 wind blew at the time, which appears to have been a little to the 

 «uit of sr«uth. Appearances verv similar to ripple marks are to 



be found in some of the layers above the one I have described. 

 They are not, however, sufficiently distinct and continuous, to 

 settle the question of their origin. These rijsple marks appear to 

 indicate the presence of a beach or boundary of the sea at that 

 time. The occurrence of a beach of a fresh water lake during 

 the present epoch, in the same locality, is an interesting coinci- 

 dence. The gradual subn:ergence of the land after the harden- 

 ing of the sand on the Silurian beach, and the varying depths 

 of the sea which eventually covered it is sufficiently indicated 

 by the superimposed layere of shales and sandstone, with fucoides 

 corals and other organic remains. Proceeding now to the other 

 fossils, found in these rocks, we have here a huge orthoceratite, 

 or straight horn, two feet seven inches in length, and about 

 five inches in breadth at its broadest extremity. It was found 

 between layers marked three and four, on the diagram. It is 

 much flattened by pressure, but the mai-kings in some jjarts are 

 still distinct. The snecimen was broken in the act of being 

 raised from its sandstone bed. The orthoceratidas (straight 

 horns) constitute a very numerous f;^mily of molluscous animals. 

 They were, probably, creeping animals protected by a very 

 elongated shell, which is divided into partitions, called septa, 

 connected b}' a tube or siphuncle, both of which can be 

 seen in specimens on the table, from which the outer shell is 

 removed. Some species of the orthoceratidre wei^e of enormous 

 dimensions ; individuals have been found in this counby upwards 

 of six feet in length. The position of the li\ing shell is sup- 

 posed to have been upright, the large extremity downwards, the 

 body of the shell swaying in the water. Upwards of sixty 

 species have been described by Hall as belonging to the Loraine 

 Shales, and the fossihferous rocks which lie below them in the 

 State of New York. Considerably more than one hundred sjiecies 

 are now known to geologists. 



The gastropods ('snails, limpetsj had their representatives in the 

 Loraine Shales. The shells of these animals present many very 

 beautiful forms. The number of fossil species found in the 

 Lower Silurian is not great. The individuals, however, are gene- 

 rally elegant in their outline and structure. 



The gastropods exhibit all the types of molluscous animals in 

 a ^•ery prominent de!>-ree. This shell, CyrtoUtes ornaivs, is con- 

 sidered to be characteristic of the Loraine Shales. It is not un- 

 common in the rocks of the Garrison Common; and very beautiful 

 specimens may occasionally be found. The shell is an important 

 one ; for, besides being characteristic, it is very easily recognized. 



The conchifei-s, of which the oyster is a type, were rare at 

 this period. The remains, however, of particular species belong- 

 ing to some extinct genera are remarkably abundant. These are 

 specimens of a very pretty shell, whose casts are exquisitely pre- 

 served in in the Soft Shales. It is named Pterinia C'arinata and 

 is also characteristic of the Loraine Shales. Its apparent resem- 

 blance to certain species of common sea-shells is striking, but not 

 so much so as the resemblance of the one I hold in hand to the 

 common muscle. It rejoices in the name of ModioJopsis Modio- 

 laris. When layers of soft shale are remo\"ed froni their resting 

 ])lace, and then carefully split with a knife or chisel, the casts of 

 this shell, which is frequently revealed, presents such a modern 

 aspect, — their forms and markings being so exact and perfect, and 

 apparently so fresh, — that it becomes difficult to believe that we 

 are looking at the cast of a shell, whose li\ing occupant existed 

 so far back in the unlathomable past that no effort of the imagi- 

 nation can convey the mind to the epoch of its life. It is truly a 

 medal of creation, for while every portion of the original shell 

 has long since been dissolved away, yet its exact impression has 

 been produced in and retained by the hardened mud of the sea 

 in which it once lived and died. This little slab is full of the 

 impressions of a very interesting species of shell. The genera to 

 which it belong* has members distributed, not only throughout 



