SECTION IV. 1883. f 165) 7] Trans. Roy. Soc. CANADA. 
X.— The Geological History of Serpentines, including Notes on pre-Cambrian Rocks. 
By Tuomas Sterry Hunt, M.A., LL.D. (Cantab.), FRS. 
(Presented May 23, 1883.) 
I.— Historical Introduction.—Discordant opinions as to the geognosy of serpentine; views of various European geo- 
logists ; of American geologists; geological survey of Canada. Origin of crystalline rocks; plutonism; 
metasomatic hypothesis ; neptunism ; aqueous origin of magnesian silicates. A fundamental question in 
geogeny. 
II.—Serpentines in North America.—Laurentian and Huronian serpentines ; those with the younger gneisses and 
mica-schists. Serpentines of Chester Co., Pennsylvania ; of Staten Island, Hoboken, Manhattan and New 
Rochelle; Taconian serpentines in Pennsylvania. Silurian serpentine of Syracuse, New York; its history. 
Sepiolite and other hydrous magnesian silicates. 
III.—Serpentines in Europe-—The hypothesis of their igneous origin. Nomenclature of serpentines and related 
rocks. Views of some Italian geologists. Serpentines at the geological congress of Bologna. 
IV.—Rocks of the Alps and the Apennines.—Early views. Studies of Gastaldi, von Hauer and others. Ancient gneiss ; 
pietre verdi or greenstones ; newer gneiss; youngest crystalline schists. Four pre-Cambrian groups in the 
Alps defined. Rocks of the Apennines and the adjacent islands. 
V.—Italian Serpentines.—Their classification ; plutonic and hydroplutonic theories of their origin. Serpentines of 
Tuscany, Liguria and the Alps. Antiquity of the so-called tertiary serpentines. 

VI.—The Genesis of Serpentines—Theories of plutonic and neptunian metasomatism; diagenesis. The derivation 
of serpentine from olivine, and the hydroplutonic hypothesis considered in relation to vulcanism. 
Theory of original deposition. History of olivine rocks. 
VII.—Stratigraphical Relations of Serpentines.—Their supposed intrusive character considered. Stapff on the ser- 
pentines of the St. Gothard. 
VIII.—Conclusions ; followed by an analysis of the Contents of Sections and Note. 
I.—HIstoricaL INTRODUCTION. 
§ 1. Few questions in geology are involved in greater obscurity or more contradiction, 
than the history of serpentine-rocks. As a preliminary to a discussion of certain observa- 
tions by myself and others thereon, it seems, therefore, desirable to recall some passages 
in this history which may serve to show the differences of opinion now existing and, it is 
hoped, prepare the way for their reconciliation. These differences may be considered 
under two heads: namely, the geognosy of serpentine, or its relation to the other rocks of 
the earth’s crust, and the geogeny, or the origin and mode of formation of serpentine. 
Setting aside for the moment the question of the occurrence of serpentine as an acci- 
dental mineral disseminated in calcareous rocks, and considering only its occurrence in 
rock-masses, either pure or mingled with other silicates, the first question which presents 
itself is whether such massive serpentines are contemporaneous with the enclosing rocks, 
or whether they have been subsequently intruded among these :—in other words, whether 
serpentines are indigenous or exotic rocks. 
