THE TRAP DYKES OF THE ORKNEYS. 



903 



Locality. 

 400 yards east of pier, Rousay, 

 Avalshay Point, Rousay, . 

 Sourin Mill, Rousay, 

 Geo of Dykend, Saviskail, Rousay, 

 Behind farmhouse, Saviskail, 

 Hoxa, South Ronaldshay, west, . 



„ „ east, 



Widewall, „ 4 or more dykes, 



East of Mermaid's Rocks, Deerness, 



Grainbank, Kirkwall, 



Skaill, Rousay, 

 Quoynamuckle, Rendall, . 

 Tingwall, Rendall, 

 Kongie Geo, Saviskail, Rousay, 

 Wartholm, Copinshay, 



Kennibuster Point, east, . 



„ west, . 



Kennibuster Burn, east, . 



„ mid, . 



„ west, . 



Knowes, Burn of Ireland, Stenness, 



Naversdale, Orphir, 



Width. 



Bearings. 



Notes. 



. 4 ft. 



E. 20 N. 



... 



. 10 ft. 



E. 20 N. 



• • • 



. 2 ft. 



E. 30 N. 



• • • 



. 3 ft. 



E. 20 N. 





. 2 ft. 



E. 20 N. 





. 5 ft. 



E. 20 N. 



see p. 879. 



see PI. II. figs. 1, 2, 4 



. 4 ft. 9 in. 



E. 25 N. 



see p. 879. 



see PL II. fig. 2. 



. 7 ft. 



E. 30 K 



see p. 869. 



. 2 ft. 6 in. 



(?) 



... 



MONCHIQULTES. 







. 2 ft. 6 in. 



about E.N.E. 



see p. 887. 



see PI. III. fig. 3. 



. 2 ft. 



E. 20 N. 



see p. 888. 



. 4 ft. 



E. 25 N. 



see p. 888. 



. 2 ft. 



E. 30 N. 



see p. 888. 



. 4 ft. 6 in. 



E. 20 N. 



see p. 888. 



. 3 ft. 6 in. 



E. 40 K 



see p. 889. 



ALNOITES. 







. 5 ft. 



N. 20 E. 



see p. 892. 



. 2 ft. 



N. 35 E. (?) 

 twisting 



see p. 896. 



. 2 ft. 



K 20 E. 



see p. 894. 



. 1 ft. 6 in. 



N. 20 E. 



see p. 894. 



. 3 ft. 



N. 20 E. 



see p. 894. 



. branches, 5 ft., 



N. 10 W. 



see p. 896. 



3 ft., 2 ft. 









N. 20 W. 



see p. 895. 



Long Geo, Goltick, Holm, 



MELILITE-MONCHIQULTE. 



. 2 ft. 



K 10 E. 

 twisting 



see p. 896. 



see PI. III. fig. 6. 



LIST OF AUTHORITIES. 



I. Jameson, Mineralogy of the Scottish Isles, 2 vols. Edinburgh, 1800. 



II. Sir Archibald Geikib, "The Old Red Sandstone of Western Europe," Part I., Trans. Roy. Soc. of 

 Edin., vol. xxviii., 1878. 



III. B. N. Peach, F.R.S., and John Horne, F.G.S., "The Old Red Sandstone of Orkney," Trans. Roy. 

 Phys. Soc. Edin., 1890. 



IV. J. R. Tudor, The Orkneys and Shetland (London, 1883), with a chapter on the " Geology of 

 Orkney," by B. N. Peach, F.R.S., and John Horne, F.G.S. 



V. M. Foster Heddle, M.D., F.R.S.E., "The Geognosy and Mineralogy of Scotland." Part V.— 

 Orkney. Reprinted from the Mineralogical Magazine, vol. iii. Truro, 1880. 



VI. W. C. Brogger, "The Basic Eruptive Rocks of Gran," Quart. Journ. of the G-eolog. Soc, 1894, 

 vol. L. p. 15. 



VII. John S. Flett, "Old Red Sandstone of the Orkneys," Trans. Roy. Soc. Edin., vol. xxxix., 1898, 

 p. 383. 



VIII. W. C. Brogger, " Die Eruptivgesteine des Kristiania gebietes." III. Das ganggefolge des laurdalits, 

 Kristiania, 1898. 



IX. J. F. Kemp and V. F. Masters, " The Trap Dykes of the Lake Champlain Region," Bulletin of the 

 United States Geological Survey, No. 107, 1893. 



X. W. Cross, "Some Secondary Minerals of the Amphibole and Pyroxene Groups," American Journal 

 of Science, vol. xxxix., 1890, p. 359, 



