100 Vrof. C. Lapicorth — Close of the Highland Controversy. 



6. In some spots the basement beds of the local Palseozoic rocks 



rest uncontbrmably ^ upon one member of the Eastern meta- 

 morphic series : while — 



7. Generally speaking, the line of junction of the unaltered Palaeo- 



zoic rocks and the Eastern Metamorphic Series is a great fault ^ 

 and overthrust, along which — 



8. The Eastern metamorphic series has been forced^ over the 



Silurian rocks by Earth-movements which have acted since 

 Lower Silurian (Ordovician) times. 



9. The schists and gneisses of Sango Bay and Farrid Head, which 



repose locally upon the Durness Limestones, do not form part 

 of a continuous sedimentary succession. They are a part of 

 the Eastern or Upper Gneissic Series, and they are separated 

 from the Durness Limestone by planes of fault.* 



10. As these schists, etc., of Sango Bay are similar in character 

 and arrangement to the zones of pressure schists occurring 

 above the great overthrust in Eriboll,^ nearly 1 miles to the 

 S.E, they afford a rough index of the enormous distance to 

 which the metamorphic rocks have been foi'ced over the under- 

 lying sedimentary and unaltered dejDosits. 



IL Much of the Eastern Gneiss is merely the Archsean^ gneiss 

 repeated ; the Logan Rock of the Assy nt district is generally the 

 Archaean ' brought up from below the overlying sedimentaries, 

 and the Arnaboll Eock of Eriboll^ is a part of the same 

 Archaean (Hebridean) gneiss. 



(c) The Metamokphism. 



12. The petrological, lithological, and mineralogical distinctions 

 between the Hebridean gneiss and the Logan ^ and Arnaboll 

 Kocks and their equivalents are primarily due to the extra- 

 ordinary mechanical disturbances ^" to which the latter have 

 been subjected. 



13. The planes of schistosity in the Eastern Metamorphic Schists, 

 etc., between and above the great fault-planes, are not planes 

 of bedding : " they are planes of shearing and cleavage, gliding 

 planes (thrust-planes) along which the rocks have yielded to 

 the lateral crust-pressure. 



1 Lapworth, Geol. Mag. 1883, p. 127. Calla-svay, Q.J.G.S. 1883, p. 407. 

 Compare Hicks, 1880, Geol. Mag. p. 21. 



2 JMicol, Q.J.G.S. 1861, p. 86. Callaway, Q.J.G.S. 1883, p. 357, etc. Hicks, 

 Q.J.G.S. 1883, p. 157. Lapworth, Q.J.G.S. 1883, p. 421. 



2 Callaway, Q.J.G.S. 1883, p. 410. Lapworth, ('oc. ci;;. Compare Nicol, Q.J.G.S. 

 1861, p. 110, and Hicks, Geol. Mag. 1880, p. 17. 



* Mcol, Q.J.G.S. 1861, pp. 87, 88. Callaway, ibid. 1881, p. 241. Lapworth, 

 see Appendix. 



5 Lapworth, 1884, see Appendix, p. 104. 



6 Nicol, Q.J.G.S. 1861, p. 95. Hicks, Hid. 1878, p. 818, etc. etc. 



■^ Bonney, Hudleston, Proc. Geol. Assoc. 1879, p. 75 ; Q.J.G.S. 1880, p. 95. 

 Callaway, ibid. 1883, p. 410. 



8 Lapworth, Q.J.G.S. 1883, p. 422, etc. 



9 Compare Bonrey, Q.J.G.S. 1880, p. 95, etc. 

 1" Lapworth, 1884, see Appendix, p. 103. 



^' Lapworth, 1884, loc. cit. Compare also Bonney, Q.J.G.S. 1883, p. 415, etc. 



