SCIENCE. 



FRIDAY, AUGUST 31, 1883. 



SONNET. 



The years through which aiight that hath life, O Sun ! 

 Hath watched or felt thy rising, what are they 

 To those vast aeniis, when, from night to day. 

 From dawn to dark, thy circuit thou didst run, 

 With none to greet thee or regret tliee; none 

 To bless thy glowing harbinger of cloud. 

 Rose-tinted; none to sigh, when, like a shroud. 

 The banner of Xight proclaimed her victory won? 



Tet through that reign of seeming death, so long 

 To our imperfect ken, the marvellous force 

 Which means to ends adjusts in Nature's plan 

 Was bringing to the birth that eye of man 

 Which now, O Sun, surveys thy farthest course, — 

 A speck amid the countless starry throng. 



John Reade. 



NOTES ON THE GEOLOGY OF THE 

 TROAD. 



A brief summari/ of the results derived from the ob- 

 servations made in connection with the Assos expe- 

 dition. 



The terranes of the Troadic peninsula com- 

 prise a variety of stratified and massive or 

 eruptive rocl<s. The former, excepting the 

 most recent deposits, which are not considered 

 in this connection, may be divided into tiiree 

 groups, according to their mineralogical con- 

 ditions and geological age. 



Tlie most ancient group is highly crystaUized, 

 and, in all probability, belongs to the mica- 

 scbist zone of tlie ' grundgebirge ' or archean 

 formation. 



The youngest group, embracing the miocene 

 and pliocene tertiary deposits, is, in part at 

 least, well characterized by its fossils. The 

 middle group is not defined, excepting by the 

 widely separated limits of tlie other two groups. 

 It embraces rocks which may be paleozoic or 

 pre-paleozoic, as well as others which are prob- 

 ably of cretaceous and eocene age. 



The crystalline schists have their greatest 

 development in Mount Ida, of which they form 

 alcDost the entire mass. They are of many 

 varieties, all conformably interstratified, as if 

 all belonged to the same great terrane. 



True gneisses are not abundant, anc^ occur 

 chierty upon the north side of Mount Ida, under 

 such conditions that they appear to overlie the 



No. 30. — 1883. 



schistose rocks. In Ilagi ouklouren-dagh the 

 mica is in large part replaced by hornblende, 

 so that the gneiss has a somewhat dioritic 

 aspect. 



In the schistose rocks, chiefly amphibolites, 

 hornblende is one of the most widely- distrib- 

 uted and abundant minerals. It generally 

 ai)pear8 as actinolite, and not infrequently- con- 

 stitutes almost the whole of the rock in which 

 it occurs. With amphibole, at times, are as- 

 .sociated, besides plagiot^lase, more or less 

 quartz, epidote, magnetite, titanite, and rutile. 

 True mica-schists are of less common occur- 

 rence interstratified witli the amphibolites. 



Near the centre of IMount Ida, the oldest 

 rocks crop out ; and among them are talc- 

 schists, which, by the gradual addition of oli- 

 vine, pass into small lens-shaped masses com- 

 posed almost exclusively of the latter mineral. 

 According to the nonienclatuie of Brogger, 

 this rock should be called olivin'e-schist. By 

 alteration it gives rise to serpentine with the 

 characteristic reticulated structure which ever 

 marks the serpentine derived from olivine. 

 Occasionally the fibrous serpentine forms veins 

 of considerable size in the a<ljacent rocks. 



The olivine-scliist, where purest, has no schis- 

 tose structure. The passage from talc-schist, 

 in which no olivine occurs, to that composed 

 almost completely of olivine, takes place some- 

 times within a siiort distance. The chiuf mass 

 of the rock, however, is a middle stage between 

 tlie two extremes, having a distinct schistose 

 stnieture, and composed for the most part of 

 olivine and talc, besides considerable qtumtities 

 of pyroxene, as well as other minerals not yet 

 determined. At various intervals through- 

 out the zone of schistose rocks, occur rather 

 coarselv crystalline white limestones. 



The structure of Mount Ida is a compara- 

 tively simple anticlinal, with so short an axis 

 extending east and west that the upper portion 

 of the mountain is approximately a dome. 



The highly- crystalline stratified rocks are 

 ])erhaps the chief topographical determinants 

 of that region. Their position and distribution 

 indicate, that, in the earlj' stages of its devel- 

 opment, the peninsula of the Troad was repre- 

 sented by several islands, which furnished much 

 of the detritus for subsequent formations. 



The rocks of the middle zone are for the 

 most part semi-crystalline limestones, a very 

 ferrugiqoifs (|uartzite, together with greenish, 



