288 TRENTON LIMESTONE. 



Going back to Bridport we find on the west side of the Chazy limestone anticlinal, an 

 outcrop of Trenton limestone, at Frost's Landing. It forms an anticlinal by itself; for 

 both north and south of it Utica slate is found dipping from it both to the north and to the 

 south. This was found to be a good locality for fossils especially the Lingulse. The Tren- 

 ton occurs next north of Chimney Point, on the west side of the Chazy, which it follows 

 into the State from Crown Point, N. Y. The rock is in place upon the shore a mile north 

 of the ferry, and upon the land at Mr. Strong's house, and at a Mr. Goodale's, according 

 to Prof. Adams. This range gradually thins out in Addison. Prof. Thompson describes 

 Trenton further north in the northwest part of Panton. It is found next, upon the shore, 

 in the southwest part of Charlotte, which is upon the principal range as before described. 

 Perhaps this rock may be continuous under the lake from Panton to Charlotte. 



No other range of Trenton limestone has been noticed in Vermont, except at Highgate. 

 This is first recognized as such, a little more than a mile south of the springs, which seems 

 to be its southern limit. Some have supposed that the white limestone in Swanton, at 

 Rich's quarry and near Highgate Falls, are Trenton limestone, in a metamorphic state. 

 That range, however, lies east of, and apparently above most of the Hudson River slate, 

 and overlies the Trenton in Highgate, unless there is a fault between them. There is a 

 small thickness of slate east of Rich's quarry, which is not found east of the dove-colored 

 limestones south of Swanton. It is certain that some of the Trenton is found south of 

 Swanton, even if any are disposed to regard a part of the Swanton limestone as altered 

 Trenton limestone. 



This range widens in passing through Missisco Bay to Philipsbury, C. E., and continues 

 north of the St. Lawrence, crossing at Dischaillons, east of Montreal. 



The thickness of the Trenton limestone is 400 feet in New York, and is stated by Prof. 

 Adams, in his Second Report, to be of the same thickness in Vermont, but in one of his 

 note books he suggests that it may be even thicker. We should think that 400 feet is 

 rather too great a thickness for it, as it generally appears in Vermont, but have made no 

 oieasurements to settle the question. 



MINERAL CONTENTS. 



The principal mineral noticed in this rock, is a large vein or dike of milk-white calcite 

 ten feet wide, at Rockwell's Bay in South Hero. It dips 50 W., while the strata dip 

 slightly to the north. Very good specimens can be obtained from this vein. 



ORGANIC REMAINS OF THE BLACK EIVEE AND TRENTON LIMESTONES. 



The organic remains of the Trenton limestone as found in Vermont, are the following: 

 A few undeterminal species of marine plants; of corals, Choetetes lycoperdon (Hall), and 

 two undetermined species of Ckcetetcs, EscMropora recta (Hall), Stictopora ramosa (Hall), 

 Stromatocerium rugosum (Hall), and Graptolithus amplexicaule (Hall); one crinoid, Sclriz- 

 ocrinus nodosus (Hall) ; of brachiopod mollusks, Linyula quadrata (Eichw), L. elongata 

 (Hall), L. obtusa (Hall), L. crassa (Hall), Crania (?} filosa (Hall), Discina lameUosa 

 (Hall), Trematis terminalis (Con.), Strophomena alternata (Con.), S. textilis, Leptcena sericea 

 (Sowerby), Ortkis testudinaria (Dalm.), 0. bifomttis, var lynx (Eichw.), and an un deter- 



