NATURAL HISTORY. 



56 



FOSSIL SHELLS. 



FOSSIL SPONGE. 



FOSSIL ■WOOD. 



to a very recent geological period, or is 

 what is called a Pleistocene, or post tertiary 

 formation. These remains are mostly shells 

 of molluscs, "with a few remains of whales, 

 seals and fishes ; and thej' aj-e nearly all 

 identical in species 'witli those living on the 

 coast of New England, and in the Gulf of 

 St. Lawrence. 



Nearly an entire skeleton of a whale was 

 found in this formation, in Charlotte, as 

 mentioned on page 15. A number of the 

 lumbar and caudal vertebrae of a whale, 

 probably of the same species, have also 

 been found in a similar clay bed, on the 

 Island of Montreal, as already stated in a 

 note on page 20. The species of fossil 

 shells, found in this formation, are quite 

 numerous, but the most common in the 

 Champlain valley are the following : 



Sanguinolaria Jusca. — 

 This is the most common and 

 abundant species. It is met 

 with, in hundreds of places, 

 along the banks of the lake 

 and streams, in digging wells, in making 

 excavations for roads and railroads, and in 

 cultivating the lands. It is met with at 

 the distance of several miles from the lake, 

 and often more than 200 ieet above it. 



,^^7t;»iss:;??j^<v Saxicava rugosa. — 



/' " " " N This species is quite 



f -common, but is not so 



^^^^^-^'^-^--as^js^ generally diffused as 



the preceding. The 



shell, being thick and strong, is often found 



in a very good state of preservation. 



M>ja arcnaria. — This is the largest of the 

 fossil shells found here. There are fewer 

 localities of this than of the two preceding 

 species, but at some of these the individuals 

 are so multiplied as to be exceedingly nu- 

 merous ; and they are often well preserved. 

 jYuculaportlanilica. — This shell is found 

 low in the blue clay, but is not abundant. 



Mytilus edulis has been found only at a 

 few localities ; but in some cases the indi- 

 viduals are quite numerous. They are 

 seldom well preserved. 



The Sanguinolaria fusca is a littoral 

 mollusc, which lives and propagates only 

 in the sweep of the tide. This fact throws 

 light upon the progress of subsidence of the 

 St. Lawrence and Champlain vallies, by 

 which the ocean, (from which the Lawren- 

 cian deposit took place,) was admitted into 

 them. In various strata we have this 

 mollusc embedded in the position in which 

 it buries itself, when alive, and w^here it 

 had evidently propagated, with the two 

 valves united, and the epidermis undis- 

 turbed. These strata must, therefore, have 

 been at the surface of the ocean, when the 

 animals were buried. But we find them 

 thus bedded in strata more than 60 feet 



apart, in vertical height, showing clearly 

 that the subsidence was a very gradual one. 



Fossil Sponge. — While digging a well in 

 Alburgh, about four years ago, at the depth 

 of 11 feet, the workmen came upon a hori- 

 zontal stratum of what appeared to be mats 

 of hair. It was in quite compact clay, was 

 about two inches thick, and extended over 

 nearly the whole bottom of the excavation. 

 It excited much curiosity, but very little 

 of it was saved. Having obtained a small 

 quantity of it, I sent it in a letter to my 

 friend. Prof. J. D. Dana, who pronounced 

 it, both upon his own authority and that of 

 Prof. Bailey, of West Point, to be Fossil 

 Marine Sponge. 



Fossil Wood. — It is not uncommon, in 

 the vicinity of Lake Champlain, to find 

 wood, and other vegetable matter, buried 

 at various depths in the earth, in places 

 and under circumstances, in which we 

 should little expect it. There have been 

 several cases of this kind in the village of 

 Burlington, which I shall here mention, 

 and all of which, with one exception, have 

 fallen under my own observation ; and that 

 one is well attested. 



The first of these cases was in 183-5. That 

 year the Hon. Alvan Foote, who resides, 

 about 40 rods, directly north of the Uni- 

 V ersity , dug a well near his residence. Tlj£ 

 surface of the ground, at the place, was 

 originally covered with a heavy growth of 

 timber, and large boulders were thickly 

 scattered over it. In digging the well, the 

 first four feet were loose earth and gravel. 

 The next 20 feet were what is commonly 

 called hardpan, consisting of pebbles, 

 gravel, sand and clay, very solidly com- 

 pacted together. Next came a ? andy earth, 

 which could be shoveled without being 

 loosened with a pickaxe, for about 4 feet, 

 when the workmen, to their astonishment, 

 broke into a hollow cavity, extending across 

 the bottom of the well. 



Upon examination, the cavity was found 

 to have been occupied by a large tree, sup- 

 posed to be pine, parts of which were re- 

 maining, and quite sound. It had been 

 embraced by the sand; but, a few inches 

 lower down, a stratum of black carbonaceous 

 matter was found, resembling muc!?. The 

 natural surface of the ground, where the 

 well was dug, was about 240 feet above 

 Lake Champlain, and the tree was 29^ feet 

 below the surface of the ground. 



The next case was in 1850. In making 

 the excavation, on Pearl street, for the 

 reservoir, connected with the aqueduct, 

 which supplies the lower part of Burlington 

 with water, at the depth of 13 feet from the 

 surface of the ground, a large amount of 

 wood, sticks and leaves were found embed- 

 ded in clean gravel. The locality is about 

 200 feet above the lake, and the size of the 



