1 
F Kingdon Ward—The Land of Deep Corrosions. 209 
described, it is desired to draw the attention of petrographers to the 
structure, in the hope of finding it to be of wider occurrence. 
In quartz-porphyries with micro-poikilitic structure the quartz 
phenocrysts are often surrounded by a network of quartz laths in 
optical continuity. Geijer regards the laths as paramorphic after 
tridymite, and suggests that their optical continuity with the 
phenocrysts may be due to inoculation by the latter. The discovery 
of the granular quartz suggested the possibility of these phenocrysts 
themselves being paramorphs of tridymite, and through the kindness 
of Professor P. D. Quensel, of Stockholm, I was permitted to look 
through Dr. Hedstrom’s slides described by Geijer. There were no 
traces in the phenocrysts of any structure similar to that in the 
Faskrudsfjord rock. Unfortunately there are no quartz phenocrysts 
in the Icelandic rock, and it is impossible to speak definitely yet on 
the question of phenocrysts and micropoikilitic quartz. 
I wish to express my thanks’ to Professor W. C. Brogger for 
permission to work at the Mineralogical Institute of the University 
of Christiania, and to Professor V. M. Goldschmidt for help and advice. 
REFERENCES. 
1. A. LAcRorx, ‘‘ pat la tridymite du Vésuve et sur la genése de ce minéral 
par fusion ’’: Bull. Soc. Fr. Min., xxxi, 1908. 
hele Peay ‘“‘ Beitrage zur Kenntnis der islandischen Liparite’’ : 
Geol. Foren. Férhandl., No. 140, Bd. xiii, 1891. 
3. MALLARD, Bull. Soc. Fr. Min., xiii, 1890. 
4, P. GuigER, “ Poikilitic Intergrowths’’: Geol. Féren. Férhandl., Bd. xxxiv, 
Heft i, 1913. 
EXPLANATION OF PLATE IX. 
Fig. 1.—Nicols crossed. Section of the Hlidarfjall Liparite (Professor 
- Backstrém’s collection), showing an assemblage of thick twinned 
tridymite crystals. x 40 
,, 2.—Nicols crossed. Section of a fragment in the Faskrudsfjord rock, 
showing typical development of quartz lamelle—paramorphs of 
tridymite—in a cavity. The lamelle comprise two quartz 
individuals. The light streaky patches in the groundmass are 
micropoikilitic quartz. x 40. 
», °%.—WNicols crossed. Section showing a complex of quartz lamelle— 
paramorphs of tridymite—in a cavity in a fragment of the Faskruds- 
fjord rock, and optically resolvable into five individuals. x 120. 
,, 4. Nicols crossed. From the Faskrudsfjord rock, showing a phenocryst 
of soda-microcline with albite and pericline twinning, and holding 
as an inclusion quartz lamelle, paramorphs of tridymite. x 120. 
,, 98. Nicols crossed. From the Faskrudsfjord rock. Shows an aggregate 
of quartz grains with traces of tridymite lamellar forms. x 120. 
V.—Fortuer Groroetcat Nores on tHe Lanp or Drsp Corrostons.' 
By F. KINGDON WARD, B.A., F.R.G.S. 
N the Grotoercan Magazine for April, 1913,” I drew attention to 
certain features of the country forming the Yunnan—Tibet border. 
Further travels there in 1913 and through the Burmese hinterland 1 in 
1914 enable me now to supplement and ‘extend those notes. 
1 The rock specimens collected during my journeys of 1913 and 1914 have 
not been described. Their examination may help to throw some light on the 
problems here indicated. 
2 ** Geological Notes on the Land of Deep Corrosions,’’ pp. 148-53, 
Pls. V and VI. 
DECADE VI.—VOL. III.—NO. V. i 14 
