TABLE OF CONTENTS. 



VH 



C. II. Hitchcock denionsUutes tlie iinport;mce of mineral characters in the 



classiiicatiou and idcntifKiation of rocks, 393; the rocks of New Hampshire 

 classiiied on that basis, 393; Hunt caUed on by C. 11. Ilitclu^ock to decide 

 which way the porphyritic gneisses dip, 394 ; Huntington points out facts 

 indicating that the Concord granite is intrusiye, 394; C. H. Hitchcock states 

 his views in Final Report, Vol. 11., in regard to tlte importiince of not "obscur- 

 ing observations" by "individual speculations," 394, 395; sonic results of 

 investigations made to ascertain how for 0. H. Hitchcock was able to distin- 

 guish and prop(n-ly name rocks, 395-397 ; authenticity of siiecimeus examined 

 by us, 397 ; notii^e of our tabular view of the elassitications presented at various 

 times by the New Hampshire Survey, under 0. H. Hitchcock, 397, 393. 



EASTERN MASSACHUSETTS. 



S. Godon's observations in 1807-8, 398 ; his division of the formations in the 

 vicinity of Boston, 398-400 ; Ma(U,uiie'.s geological map, 400 ; error of Hunt 

 in describing iVlaclure's work, 400 ; J. F. and S. L. Dana's coutribirtion to the 

 geology and mineralogy of the region near Boston (1818), 401, 402; Eaton's 

 Index to the Geology of llic Northern States, 402; Thomas Cooper, 1822, 

 recogniz(!s the volcanic character of some of the rocks near Boston, 403 ; Hitch- 

 cock's first pubiieation (1824) in regard to geology of Eastern Massacliusetts, 

 403 ; Hitchcock contributes to the geology of the same region in Eaton's Survey 

 of the Erie Canal, 403, 404. J. W. Weuster, 1824-25, publishes Remarks on 

 the Geology of Boston and its Vicinity, 404. HrrcHcocK's Report, 1833, and 

 his tluioretical views as set forth in that volume, 405-409 ; his final report, 

 1811, 409, 410 ; his theories sot forth and commented on, 410. Puescott's 

 geological investigations in Essex County 839), 410. 



Hunt, iu 1854, refers the limestones of Eastern Ma.ssaehu setts to the Devonian, 411 ; 

 he states, iu 1801, that he recogni;;es in New England or Southeastern Canada 

 "nothing lower than the Silurian," 411. Discovery of fossils near Boston, and 

 recognition of the locality from whicli they eanie, 411 ; various statements as to 

 the dip of the rocks from whii'h these fossils came, 411, 412 ; Hunt, in 18(16, 

 on the limestones of Eastern Massachusetts, considering it doubtful whether 

 they may not be Laurentiau, 412 ; C. II. Hitchcock, 1867, considers the gneiss 

 and hornblende schist of Andover to "belong to the Eozoic ages," 412 ; his 

 rep(n-ted facts doubted, 412. Hunt, in 1869, describes the granite of New Eng- 

 land as being a sedimentary rock, and containing traces of fossils ; in 1870 he 

 say,^ that the granites of Cape Ann and Qnuicy are " probably intrusive " ; in 

 1873, that tlie granites of Rockport are "distinctly eruptive," 413 ; neeossary 

 pliysical conditions resulting from Hunt's theories, 413; Bickmkll finds 

 Kozoon in liinestiinc at Newbiuy, 413, 414 ; Hunt considers this proof of the 

 Laurentiau ago of these rocks, 414. 



SuALi'Ui, in 1869, considers the stratified origin of the syenites of Eastern Massachu- 

 setts clearly proved, — the syenite being seen to pass into " uncpestionably 

 sedmientary rock," 414 ; Ids geological observations sliown to be incorrect, 414. 

 Hunt, in 1870, <'onsiders the finding of the Eozoon at Chelmsford, and its 

 identification by Dawsou, as proof of the Laurentian age of the limestones of that 

 region, 415 ; Hunt, in 1870, refers the gneiss of Eastern Massachusetts to tlm 



