388 NOTES ON THE GEOLOGY 



the feldspar has been more or less decomposed. An example of 

 this sort I have described as occurring in Berkshire county in 

 Massachusetts, in my Final Report on the geology of that State. 

 In Massachusetts, also, this rock is used for millstones. At 

 Broosa the rock is sometimes highly cavernous, from the exist- 

 ence of small segi-egated veins, between which some highly ferru- 

 ginous substance has nearly disappeared. The cells thus produced, 

 take the form of a cube or a parallelopiped ; and, in some of the 

 specimens, the whole mass appears as if it might be a vegetable 

 reiic, (Nos. 160, 163.) A similar appearance exists in some varie- 

 ties of the limestone found near the foot of Olympus. (No. 166, 

 from ruins in Broosa.) But I donbt, in either case, whether genu- 

 ine vegetable remains exist. This sandstone, or perhaps meta- 

 morphic gneiss, passes sometimes into a decided conglomerate ; 

 as Nos. 161, 162. The imbedded pebbles are quartz, hornstone, 

 and jasper. In the same rock occur fine tabular crystals of sul- 

 phate of baryta, with dihedral summits, and of a color inclining 

 to wine yellow, (No. 165.) A quartzose conglomerate exists, also, 

 in connection with the pseudo-burrhstone in Massachusetts, above 

 alluded to ; and upon the whole the resemblance between the 

 two cases is rather strong. 



The chain of Olympus reaches its greatest height, of nine 

 thousand one hundi-ed feet, not far from Broosa. " This chain," 

 says Mr. Van Lennep, "advances from the eastward, rises to its 

 loftiest summit, and stops suddenly short. The earlier rocks it 

 has displaced form a gradual slope, which extend a mile or two 

 beyond Broosa westward." (Mr. Van Lennep here introduces 

 a section, showing the rocks on this slope in the following order : 

 first, primary or early secondary limestone : secondly, calcareous 

 tufa with vegetable impressions : thirdly, limestone and argilla- 

 ceous slate : fourthly, rocks of igneous origin : fifthly, early sec- 

 ondary limestone and argillaceous slate : sixthly, limestone con- 

 glomerate. He then proceeds to notice the rocks north of Olym- 

 pus.) "The chain runs east and west. Immediately north of 

 it, lie generally rich alluvial plains. These are sometimes in- 

 terrupted by limestone hills. Beyond the plains arc also hills of 

 the same limestone. Further on towards Ghunlik, the ancient 



