Remercs— Classification of Rocks. 425 



(&) Plutonic, e.g. the granites. 



II. — Metamorphic Crystalline Schists. — Most probably the product 

 of the transmutation of sedimentary rocks, but in respect of their 

 mineralogical composition closely allied to the igneous, e.g. gneiss, 

 mica-schist, chloride-schist, etc. 



III. — Sedimentary Eocks. — The product of deposit : — 



1. Argillaceous rocks, such as clay and argillaceous shale. 



2. Limestone rocks, such as limestone and dolomite (including 

 gypsum and anhydrite). 



3. Siliceous rocks, e.g. Sandstones and conglomerates. 



4. Tufa formations. 



The above are the groups of principal rocks which occur in masses 

 of great extent. 



rV. — We shall next range those rocks of less frequent occurrence, 

 or which only form subordinate strata or separate beds, and whose 

 origin is in part still doubtful, without attempting, in their case, 

 a logical classification. To this series belong, for instance, many 

 silicates, the carbonaceous rocks, the ironstones, serpentine, etc., and 

 some other rocks of problematical character. 



Y. — Finally we shall instance those rocks which are essentially 

 composed of one mineral, such as quai-tz, opal, etc." 



The author's observations on the probable mode of formation 

 of minerals are very trustworthy and reliable, and he has evidently 

 devoted much time and labour to the subject. 



Dr. Cotta's Classification of Eocks will, no doubt, be the students 

 manual for many ensuing sessions in all colleges where lithology 

 is taught, but JBristoio's Mineralogy must still be in demand by 

 every student, because the work is so carefully executed, its arrange- 

 ment is so simple, and the book so handy for reference at all times. 



We shall notice Dr. Cotta's work again in a future number. 



IS-IEI^OISTS J^ISTJD :PI^OCESIDIlsrC3-S. 



Edinburgh Geological Society. — On May 3Qth, the eleventh 

 ordinary meeting of this Society for the session was held in their 

 rooms. No. 5, St. Andrew Square. — Mr, Eoderick A. F. A. Coyne, C.E., 

 Vice-President, in the chair. 



Mr. Thomas Smyth read the second part of a paper "On the Up- 

 heaval of the Shores of the Firth of Forth, and part of the East 

 Coast of Scotland, during the Human Period." He briefly recapitu- 

 lated the evidences of upheaval contained in his former paper (a 

 report of which appeared in the Jmie number of the Geological 

 Magazine). The second part of the paper was entitled, "On the 

 Upheaval of our Shores between the time when a Celtic population 

 first inhabited the Lowlands of Scotland and the present day ; with 

 special reference to a Eise of the Land smce the period of the Eoman 

 Occupation, and to a Eise within the last half -century." He ex- 



