TRANSACTIONS OF SECTION C. 



"29 



ihe otiier localities. lie saw no relation whatever between the typical Iliironians 

 jijid fill' IJiitish Tebidian,' and other rocks wiiieh had been compared to tiieni, 

 thoiifrli tlie latter had some resemblanc' to the * Animike' frroup of l*ort Arthiii'. 

 IIimIivw sjx'cial attention to the volcanic naUire of a <rreat part of the Ilastinfrs 

 iiiics, niid compared these with the so-called ' Arvonian ' portion of the Pre-("iini- 

 brian of Cireat liritain. 



aess of whicli 



0. ())( the Soutlnairtl Ending of a yrrat Si/ndinal in thf Taconk liamje.^ 

 By Professor James D. 1)ana, LL.D. 



Tlio Taconic Ranfro, which pave the term 'Taconic ' to geology, lies in "Western 

 .\V\v llngland, between Middlebury, in V(,>rmont, on the north, and Salisbury, in 

 Connecticut, on tlie south. In former papers, ])ublished in the ' American Journal 

 of Science,' tiie author has shown, lir.'-t, that tlie rocks constituting the range vary 

 a? we go from north to south, from roofing-slate and hydromica (or .'^ericite) 

 sciiist to true chloritic and garnetiferous r\ica schists; secondly, that the.se schists 

 lie mostly in a synclinal or compound synclinal; thirdly, that the crystalline 

 limeftoiic along the eastern foot is one with that along the western, the limestone 

 passing under the schist as a lower member of the synclinal; and, fourthly, that. 

 >inre the limestone contains in Vermont (according to tht; discoveries of the 

 Vermont Geological Survey, and also of Mr. A. Wing), and in the State of New 

 York, fossils of the I^ower Silurian, ranging from the inferior divisions to the 

 liifrher, the Taconic schists are probably of the age of the Hudson River group or 

 Llandeilo tings. 



The author's papers further show that while a large part of the Taconic Itonge 

 has p.u eastward dip on both the east and west sides, a southern portion about 

 twelve miles long, consisting of Mount Washington in south-western Massachusetts 

 iind its continuation into Salisbury, Connecticut, is a broad tray-shaped synclinal, 

 the dips of the two sides being toward one anf)ther, like the sides of an ordinary 

 tioiigli. The width of the broad synclinal between the limestone belt on either 

 side is about live miles. 



As the result of investigation during the last two years, the .synclinal character 

 oftlii.s Mount Washington part of the Taconic Range is, illustrated in the ])aper by 

 new sections, an-^ liy facts connected with the dying out of the great syncliiml (or 

 torapound synclinal) in the town of Salisbury. 



The mean height of Mount Washington above the sea-level is about 2,000 feet, 

 and above the wide limestcme region on either side and to the south, about l,i'50 

 feet. The synclinal virtually ends along an east and west line through the village 

 of Lalieville, in the town of Salisbury, where a beautiful lake lies within 

 the limestone area. The surface of the mountain region descends 1,000 feet in the 

 scutherii, or last, three miles; and in the latitude of Lakeville tlie width, as the 

 map ]ircsented shows, diminishes abruptly from five miles to a narrow neck of six- 

 teiitbs of a mile. The area south is of limestone, and the neck of schists referred 

 to is hardly loO feet in height above it. 



The limestone may in .some places be seen emerging from beneath the .schist at 

 a small angle ; and at one locality a low oven-shaped anticlinal of limestone has 

 the scliist covering all but a narrow portion at top; the quarry meti bad to remove 

 the schist to work at the limeston ■. Severnl narrow strips or belts of limestone, 

 S. I.'j'' W. in direction, corresponding with the direction of this ])art of the range, 

 show out through the sides of the mountain where local anticlinals have had their 

 tops wiirn oft". Further, the dip of the schist over luuch of the southern slope is 

 southerly and at a small angle, but with many local anticlinals and .synclinals. In 

 addition, there are small areas of schist in the limestone region, like straggling por- 

 lions of the dwindled mountain, which appear in general to be remains of local 

 flexures. 



There is the plainest evidence that the limestone formation of southern and 



' Trintcd in full in American Journal of Science, Ser. li, vol. xxviii. pp. 268-275, 

 \vith nap and six woodcuts ; 1884. , 



If t; :«i 



fMi 



M 



ik 



i'H' 



!f 



