56 



APPENDIX TO THOMPSON'S VERMONT. 



FOSSIL WOOD. 



SHELL MARL. 



JIAEL-BEUS. 



excavation was 36 feet by 40. The sm-face 

 of the ground sloped moderately towards 

 the northwest, and was originally covered 

 heavily with timber. The earth, after 

 getting below the soil, was sand and gravel, 

 which had been washed and assorted by 

 water, and was lying in irregular beds, 

 sloping steeply towards the nortliwest. The 

 vegetable remains formed a mass in the 

 gravel about two feet wide, one and a half 

 foot deep, and 36 feet long, extending in a 

 right line, and was, at tirst, mistaken for 

 a rotten tree ; but, on breaking it to pieces, 

 it was found to consist of roots, limbs, 

 bark, stems and leaves, snugly bedded to- 

 gether, and all of a dark brown color; some 

 portions of it approaching, in appearance, 

 to brown coal. IMany of the sticks and 

 roots were perfectly sound, and exhibited 

 the structure of the wood completely, and 

 are, I have little doubt, the American 

 Larch, Finns peudulu. 



In October, in laying the aqueduct pipes 

 in the south part of the village, wood, re- 

 sembling larch and oak, were found, at the 

 depth of 10 feet beneath hardpan. And in 

 April, 1852, in deepening the well at the 

 Pearl Street House, which is midway be- 

 tween the two localities fii-st mentioned, a 

 piece of wood, ten inches long, six wide 

 and three thick, was found below hardpan, 

 24 feet from the surface. The Pearl Street 

 House is about 230 feet above the lake. 

 Wood has also 1)een found in the central 

 part of the village, in the stratified sand 

 and clay, 20 feet below the surfice. 



The question now arises — to what geo- 

 logical period does this fossil wood belong ? 

 The last mentioned certainly belongs to the 

 post tertiary or Lawrencian, for the chai'- 

 acteristic shells were found with it. In the 

 other cases, the earth was unstratified, and 

 the materials, which covered the Avood, 

 evidently belonged to the drift. But did 

 the wood belong to the drift period ? — or to 

 the tcrtiai-y which preceded it ? 



To these last questions, I would answer, 

 that, in my opinion, it belonged to neither. 

 The wood, and materials associated with it, 

 are totally unlike the lignite, and its asso- 

 ciates, which constitute the tertiary at 

 Brandon, and no one can for a moment re- 

 "•ard them as belonging to the same period. 

 But the wood is beneath or within, what 

 are, evidently, drift materials. How can 

 this be, unless the wood .and drift are of the 

 same age .' 



To answer this question, we ai'e to con- 

 sider that the elevation on which the Uni- 

 versity stands, was, at the close of the drift 

 period, a high ridge of drift deposit, having 

 a steep descent towai'ds the northeast and 

 northwest. Subsequently the whole Cham- 

 plain valley subsided, the sea was let in, and 



this elevated ridge became more andmore im- 

 mersed, and the materials forming its steep 

 declivities were gradually washed down and 

 re-arranged by the action of tlie waves. 



Previous to the burial of the tree first 

 mentioned, there appears to have been a 

 small marsh at the foot of the steep bank 

 of drift. "When the subsidence had let the 

 sea in upon this marsh, the tree was floated 

 in and lodged at the foot of the bcUik. The 

 subsidence continued, and the action of the 

 waves soon washed down the drift matei'ials 

 and covered the tree; and we have evidence 

 that the valley continued to sink till the 

 whole ridge was inunersed, and the island 

 disappeared. During this immersion, the 

 materials continued to be washed down, 

 and beaten and pressed together by the 

 surf and weight of the water, until the 

 wood became buried in the condition in 

 which it is found, since the sea was emptied 

 out by the upheaval of the valley ; so that 

 while the wood is buried in the drift, it has 

 been buried by a i-e-arrangement of the 

 drift mn.terials, since the drift period. 



Shell Marl. 



The beds of shell marl in Vermont are 

 considerably numerous, and some of the 

 beds are quite extensive ; but they are 

 entirely confined to what we have called the 

 calcario-mica slate division, on the e.ast 

 side of the Green Mountains, and to a small 

 portion of the western border of the state. 

 On that large central portion of the state, 

 which we have called the talcose slate divi- 

 sion, not a single marl-bed is known to ex- 

 ist. The marl, which constitutes these 

 beds, has a genei-al resemblance to pulver- 

 ised chalk, and consists, essentially, of 

 carbonate of lime, which has resulted from 

 the partial decay and crumbling of innu- 

 merable fresh-water shells, with sometimes 

 a slight intermixture of sand and clay. 

 Though, when wet, like a bed of putty, and 

 when dry, a pulverulent mass, still shells, 

 more or le.=s entire, are found to be scatter- 

 ed through all parts of it: and near the 

 surfoce unbroken shells ai-e often numerous. 



These shells are, for the most part, of the 

 same species, wliich are now found living 

 in the ponds and streams of the neighbor- 

 hood, and belong chiefly to the following 

 gener.i, viz: Paludina, Limnie, Physa, Pla- 

 noi'bis. Pupa and Cyclas. • 



Marl beds exist in all the counties on the 

 east side of the mountains, but are most 

 numerous in Caledonia county. There are 

 several in each of the towns of Barnet, 

 Peacham and Danville. In Orleans county, 

 and in the eastern part of AVashington 

 county, there are a few. The following sec- 

 tion exhibits the thickness and association 

 of one of these marl beds in Derbv, with 



