456 Dr. Irving — The Malvern Crystallines. 



latter was dislocated subsequently to its consolidation. Everything 

 seen goes to show that these intrusive masses were nUogether passive 

 as regards the earth-movements, which have brought the Malvern 

 crystallines into their present position. The author's observations 

 on this point thus agree with conclusions put forward during the 

 last two decades by Doctors Suess and Heim.^ The researches of 

 Dr. Callaway and Mr. Rutley make it probable that some of these 

 basic intrusive dykes, which look so much like dolerites under the 

 hammer and the lens, are really fine-textured diorites or epidioriles; 

 but this does not materially affect the view put forward here as to 

 the part they play in the geotectonic structure of the Malvern Ohain.^ 



III. Strvctnral Phenomena. — These seem to fall for the most part 

 into five categories : — 



(i.) Diorite- gneiss (rocks composed of the materials of diorite 



with a gneissic arrangement), 

 (ii.) Gneissose {flaserig) structures. 

 (iii.) PhylloUthic rocks approximating in various degrees to the 



character of a true schist. 

 (iv.) Shear-planes (often highly slickensided). 

 (v.) Crush-planes and zones. 

 A few remarks, as brief as may be, are called for on each of these, 

 (i.) Diorite-gneiss. — The most perfect examples of this were met 

 with at North Malvern. The rock here is for the most part a 

 massive diorite, but occasionally the parallel veining of the felspathic 

 and hornblendic constituents is very marked, in parts of the rock 

 which do not appear to have undergone any deformation by dynamic 

 action. The veins ai'e often a mere fraction of an inch in thickness, 

 and the veining has no relation whatever to the shear-planes which 

 intersect the rock. In other places the veined structure has under- 

 gone some deformation, giving the rock a more schistose structure, 

 the veins being apparently stretched out, the felspathic particles some- 



' Since this was penned " Suess -rechauffe " has been largely served up for the 

 delectation and mental nutriment of Sections C and E, by the respective presidents 

 of those sections. The present vsriter can hardly tind fault with Professors J. Geikie 

 and Lapworth for giving such powerful expression to ideas which have haunted 

 him for years past, as the references in his "Met. of Rocks" to Suess and Heim 

 plainly show, iiut they can hardly lay claim to novelty, seeing that the " Antlitz 

 der Erde" was outlined in (the closing chapters of) Suess's "Entstehung der Alpen " 

 (Vienna, 1875). Lapworth's conception of the " wave and trough" deformation of 

 the rind, following Suess and Heim, implies a yieldinff under-zoHe in the liihospkere, 

 which he will tind hard, with Dissipation of Energy, to harmonize with the Huttonian 

 uniformitarian doctrine, and will act as an "aqua regia" upon the gold of his 

 " wedding-ring," and the blessed union symbolized by it. And the recognition of the 

 pasnivity of iyrieons hijtoirs and oiitjlows and their location generally along the 

 concave side of the asymmetrical mountain-wave disposes once and for all of the tiction 

 of the " roots of the mountains," of a veteran writer on physical questions, even as 

 it has made it impossible for the present writer to accept it. (See in particular 

 lleim's Mechanismiis der Gehirgs-lnldung, Bd. ii., p. 178; Basel, 1878.) 



* Those who will be at the trouble to consult the author's " Metamorphisra of 

 Rocks " (pp. 53-oo) may see that on general grounds we may recognize the presence 

 of traces of highly superheated HjO as a potent factor in differentiating the aniphi- 

 bolitic rocks from the felsitic and pyroxenic magma which subsequently filled up the 

 fissures in them. This is thoroughly borne out by Dr. Kroutschoff's synthesis of 

 hornblende (see Geol. Mag. 1891, p. 303). 



