236 The hish NaUiralist, 



of this section, in which quartzites, hornblende schists, and intrusive 

 granites occurring in veins, dykes, and in mass are seen, with 

 Carboniferous limestone which has been subsequently laid down, and 

 which is undisturbed. This cutting is quite near to the station, and 

 forms an interesting and instructive diagram of faults, contortions, and 

 intrusions. Many specimens were obtained, including some of quartzite 

 and white quartz with beautiful cross-veins of red intrusive granite. 

 Some concretions of calcite, prettily stained with orange and black, were 

 found amongst the fragments on the line. On the day when Ben 

 Lettery was ascended, very fine crystals of quartz were obtained from 

 crevices on the summit of Ben Gower, and from weathered blocks. 



Some lead and copper mines near Carn Seefin, above the north- 

 western shores of Lough Corrib, were subsequently visited. Although 

 not worked at present, some samples were obtained from the '* tip." 

 One block contained galena, copper pyrites, iron pyrites, calcite, felspar, 

 and quartz as concretions in the hornblende schists in which the mineral 

 lodes occur. Pure massive epidote and fluorspar were also obtained, 

 and specimens of an intrusive rock in this neighbourhood almost 

 entirely formed of sheared pinkish-brown garnets were obtained with 

 difficulty, owing to its extreme hardness. 



The celebrated Connemara " marble" at Recess is now being worked 

 in only one quarry by about a dozen men, employed by an American, 

 who is at present executing an order for twenty pillars, each to consist 

 of five blocks measuring about four feet by three in diameter. To gauge 

 the quality of the stone a long section has been made in the side of the 

 quarry by a wire saw. This section well displays the contorted green 

 bands with grey layers at either side. The so-called "marble" is a 

 serpentine formed by the alteration of olivine introduced in the crystalline 

 bands of primitive limestone by igneous action. Similar results occur 

 in limestones around Mount Vesuvius. These serpentine bands do not 

 average more than two feet in thickness, and have been much sheared 

 and contorted, showing the " eozoonal " structure. This was formerly 

 believed to be a gigantic foraminifer when discovered in the Laurentian 

 rocks of Canada, and named Eozoon Canadense, biit its organic nature is 

 now practically disproved by the recent discovery of a similar substance 

 in limestone blocks ejected from Vesuvius.^ 



But few fossils were obtained from the Carboniferous limestone so fully 

 developed in the district, the rock being so hard as to preclude the ex- 

 traction of its organic remains in the limited time available for the 

 geologists on a mixed excursion. The usual characteristic fossils were 

 observed in abundance, and some specimens obtained in Ballj^vaughan 

 from the Burren Limestone, and in the Aran Islands. The shale-beds in 

 Aran would probably repay a fuller examination than was possible on the 

 excursion. Blow holes and the *' Worm Hole," a curious natural tank 

 are amongst the curiosities of the Aran limestones. 



* Johnston-Lavis and Gregory — "Eozoonal Structure of the ejected 

 Blocks of Monte Somma." Scu Trans, R,D,S. (2) vol. v., 1894. 



