MEMOIRS

OF

| THE GEOLOGICAL SURVEY OF INDIA, |

VOLUME XXXV, PART 1.

GEOLOGICAL'SURVEY OF INDIA.

س ڪڪ

Director.

C. L. GRIESBACH, C.I.E., F.G.S.

Superintendents.
В. D. Огрнам, A.R.S.M., F.G.S.: Tow D. La Toucue, В.А. (Cantab), F.G.S.:
С. S. MippLEMISs, В.А. (Cantab).
Deputy Superintendents.
P. №. Boss, B Sc. (London), F.G.S.:

Т. Н. HorrawD, A.R.C.S., F.G.S.: P. М. Darra, B.Sc. (London), Е.б.5.:
Е. Н. SMITH, A.R.C.S.

Assistant Superintendents.
Н. Н. HAYDEN, B.A. B.E.: E. VREDENBURG, B.L., B.Sc. (Paris), A.R.C.S.

Pala@ontologist.
Fritz NOETLING, Ph.D. (Berlin), F.G.S.

Specialist.
R. R. бімрзом, B.Sc. (Dunelm).

Sub-Assistants.
Ніва Lar: KisHEN SINGH, F.G.S.

Artist. Assistant Curator,
H.B. W. GARRICK. Т. В. BLYTH.

Registrar.
A. E. МАСА Aupsiry,

Geological Museum, Librar y, and Office, Calcutta,

KATTORALMUSERL

ооа. AQ GARS

1902.

MEMOIRS OF THE GEOLOGICAL SURVEY OF INDIA.

Vor.

Vor.

Vor.

Vor.

Vor.

VoL.

Vor.

Vor.

Vor.
Vor.

VoL.

Vot.

Vot.
Vou,

I. Royal буо, pp. 309, 1859 (ou? of print). Pt. т, 1850 (price 1 Re.) : Preliminary
notice on the Coal and Iron of Talchir.—On the geological structure and
relations of the Talchir Coal-field.—Gold-yielding deposits of Upper Assam.—
On specimens of gold and gold dust from Shué-gween. Pt. 2, 1858 (price
2 Rs): On the geological structure of a portion of the Khasi Hills.—On
the geological structure of the Nilghiri Hills (Madras). Pt. з, 1859 (Price
2 Rs.): On the geological structure and physical fea ‘res of the districts of
Bankura, Midnapore and Orissa.—On the laterite of Orissa.— On some fossil
fish-teeth of the genus Ceratodus, from Maledi, south of Nagpur. /

IL. Royal 8vo, рр. 341, 1859 (owt of print). Pt. т, 1860 (rice 2 Rs): On the
Vindhyan rocks, and their associates in Bundelkand. Pt. 2, 1860 (rice 3 Rs.)
—On the geological structure of the central portion of the Nerbudda District.
—On the tertiary and alluvial deposits of the central portion of the Ner-
budda Valley.—On the geological relations and probable geological age of
the several systems of rocks in Central India and Bengal. :

III. Royal 8vo, pp. 438. Pt. 1, 1863 (price 3 Rs.) (out of print). On the geological
structure and relations of the Raniganj Coal-field.— Additional remarks on
the geological relations and probable geological age of the several systems
of rocks in Central India and Bengal.—Indian Mineral Statistics, I. Coal.
Pt. 2, 1864 (price 2 Rs): On the Sub-Himalayan Ranges between the
Ganges and Ravi.

IV. Royal 8vo, pp. 450. Pt. 1, 1863 (rice 2 Rs.): Report on the Cretaceous
Rocks of Trichinopoly District, Madras. Pt. 2, 1864 (rice 2 Rs.) (out of
print): On the structure of the Districts of Trichinopoly, Salem, &с. Pt. 3,
1865 (price 1 Re.): On the Coal of Assam, &c.

V. Royal 8уо, pp. 354. Рі. 1, 1865 (price 3 Rs.) (out of print): Sections across
N.-W. Himalaya, from Sutlej to Indus.—On the Gypsum of Spiti. Pt. 2,
1866 (price 1 Re.): On the Geology of Bombay. Pt. 3, 1866 (rice т Re.)
(out of print): On the Jheria Coal-field.— Geological Observations on West-
ern Tibet.

VI. Royal 8vo, pp. 395. Рё. 1, 1867 (price 8 As): On the neighbourhood of.
Lynyan, %с., іп Sind.— Geology of a portion of Cutch. Pt. 2, 1867 (price 2
Rs.) (out of print): Bokaro Coal-field.—Rámgarh Coal-field.— Traps of West-
ern and Central India. Pt. 3, 1869 (rice 2 Rs. 8 As.) : Tapti and Nerbudda
Valleys.—Frog-beds іп Bombay.— Oxyglossus pusillus. .

VII. Royal 8vo, pp. 342. Pt. І, 1869 (rice 3 Rs.): Vindhyan series.—Mineral
Statistics.— Coal.— Shillong Plateau. Pt. 2, 1870 (price 1 Re.) : Karharbári
Coal-field.— Deoghar Coal-field. Pt. 3, 1871 (price 1 Ке): Aden water-
supply.— Káranpura Coal-fields. 5

` VIII. Royal 8vo, рр. 353. Pt. 1, 1872 (rice 4 Rs.): On the Kadapah and Karnul

Formations in the Madras Presidency. Pt. 2, 1872 (rice І Re.): Itkhuri-
Coal-field.— Daltonganj Coal-field.— Chope Coal-field.

IX. Royal буо, pp. iv. 358. Pt. 1, 1872 (rice 4 Rs): Geology of Kutch. Pt. 2,
1872 (price т Re.) : Geology of Nagpüár.— Geology of Sirban Hill.—Carbon-
iferous Ammonites, pp. 65.
X. Roya! 8vo, рр. 359. Pt. 1 (price 3 Rs): Geology of Madras.— Sátpura Coal-
basin. Pt. 2, 1874 (price 2 Rs.) : Geology of Pegu.
XI. Royal 8vo, pp. 338. Pt.1, 1874 (rice 2 Rs): Geology of Dárjiling and
Western Duars. Pt. 2, 1876 (rice 3 Rs.) : Salt-region of Kohat, Trans-Indus.
XII. Royal 8vo, рр. 363.. Pt. 1, 1877 (rice 3 Rs.): South Mahrátta Country.
Pt. 2, 1876 (frice 2 Rs.) : Coal-fields of the Naga Hills.
XIII. Royal 8vo, рр. 248. Pt.1, 1877 (price 2 Rs. 8 As.) : Wardha Valley Coal-
field. Ре 2, 1877 (price 2 Rs. 8 As.): Geology of the Rájmahál Hills.
XIV. Royal 8vo, pp. 313, 1878. Geology of the Salt-range in the Punjab.
XV. Royal 8vo, pp. 102. Pt. 1, 1878 (price 2 Rs. 8 As.) : Geology of the Aurunga
and Hutár Coal-fields (Palamow). Pt. 2, 1880 (rice 2 Rs. 8 Аз): Ramkola
and Tatapani Coal-fields (Sirguja).

Vor. XVI. Royal 8уо, рр. 264. Pt. 1, 1879 (price 1 Re. 8 As): Geol6gy of Eastern
Coast from Lat. 15° to Masulipatam. Pt. 2, 1880 (price т Re. 8 As.) : The
Nellore Portion of the Carnatic. Pt. 3, 1880 (price 2 Rs.): Coastal Region of
the Godavari District. ) ;

Vor. XVII. Royal 8vo, рр. 305. Pt. 1, 1879 (rice 3 Rs.): Geology of Western Sind. Pt. 2,

5 1880 (rice 2 Rs.): Trans-Indus extension of the Punjab Salt-range.
Vor. XVIII. Royal 8vo, рр. 300. Pt. 1, 1881 (rice.2 Rs.): Southern Afghanistan. Pt. 2,
; 1881 (price i Ке.8 Ав.) (out of print): Mánbhum and Singhbhum. Pt. 3,
1881 (rice 2 Rs.): Pránhita-Godávari Valley.

Vor. XIX. Royal Sy" pp. 242. Pt. 1, 1882 (price 2 Rs.): The Cachar Earthquake of 1869.
Pt. 2, 1882 (price 1 Rei: Thermal Springs of India. Pt. 3, 1883 (price.
I Re): A catalogue of Indian Earthquakes. Pt. 4, 1883 (rice 1 Re):
Geology of parts of Manipur and the Naga Hills.

Vor. XX. Royal 8vo, рр. 240. Pt. 1, 1883 (rice 2 Rs. 8 As.): Geology of Madura and
ТіппеуеПу. Pt.-2, 1883 (rice 2 Rs.8 As.): Geological notes on the Hills in
the neighbourhood of the Sind and Punjab Frontier between Quetta and
Dera Ghazi Khan. ; :

Vou. ХХІ. Royal Sea pp. 286 (out of print). Pt. 1, 1884 i(5rice 2 Rs): Geology of the
Lower Narbada Valley. Pt. 2, 1884 (price 1 Re.): Geology of Kathiawar.
Pt. 5, 1885 (Price 2 Rs.): Coal-field of South Rewah. Pt. 4, 1885 (price x

Р Bei: Barren Island.

Vor. XXII. Royal 8уо, рр. 344, 1883. The Geology of Kashmir, Chamba, and Khagan.

Vor. XXIII. Royal 8vo, pp. 232, 1891. Geology of the Central Himalayas.

Vor. XXIV. Royal буо, Pt. 1, 1887 (price т Re. 8 As.): The Southern Coal-fields of the
Sátpura Gondwana basin. Рі. 2, 1890 (rice 2 Rs. 4 As): Physical Geo-
logy of the Sub-Himalaya of Garhwál and Kumaun. Pt. 3, 1890 (rice 1 Re.

22 4 Ав): Geology of South Malabar, between the Beypore and Ponnáni Rivers.

Vor. XXV. Royal 8vo, 1896. Geology of the Bellary District, Madras Presidency.

Vor. XXVI. Royal 8уо, 1896. Geology of Hazara. :

Vor. XXVII. Royal 8vo, Pt. 1, 1895 (rice 1 Re.): Marine Fossils from ‘the Miocene of

: Upper Burma. Pt. 2, 1897 (rice 4 Rs.): Тһе occurrence of Petroleum in
Burma and its technical exploitation. 2

Vor. XXVIII. Royal 8уо; Pt. 1, 1898 (rice 2 Rs.) : Notes оп the Geological Structure of the
Chitichun region. A note on the Allahbund in the north-west of the Rann of
Kuchh. Geology of parts of the Myingyan, Magwe and Pakokku Districts,
Burma. The Geology of the Mikir Hills in Assam. On the Geology of
Tirah and the Bazár valley. Pt.2, 1900 (price 3 Rs.): The Charnockite
Series, a group of Archzan Hypersthenic Rocks in Peninsular India.

Vor. XXIX. Royal буо, 1900 (price 5 Rs.):. Report on the Great Earthquake of 12th June
8

1897.

Vou. XXX. Royal Sen Pt. 1, 1900 (rice 2 Rs.): Aftershocks of the Great Earthquake of
12th June 1807. Pt. 2, 1900 {price І Re.) : Geology of the neighbourhood of

` Salem, Madras Presidency, with special reference to Leschenault de la Tour's
observations. Pt. 3, 1901 (rice І Re.) : Sivamalai Series of Elzeolite-Syenites.
Pt. 4, 1901 (price 1 Re.): Report of the Geological Congress of Paris.

Vor. XXXI. Royal 8vo, Pt. 1, 1901 (price 2 Rs.): Geology of the Son Valley in the Rewah
State and of parts of the Adjoining Districts of Jabalpur and Mirzapur. Pt. 2,
1901 (price 3 Rs.): A Geological Sketch of the Baluchistan Desert and part
of Eastern Persia. Pt. 3 (price 1 Re.) : Petrological notes on some Peridotites,
Serpentines, etc., from Ladakh.

Vor. XXXII. Royal 8vo, Pt. 1, 1901 (rice 1 Re.) : Recent Artesian Experiments in India.
Pt. 2, 1901 (rice: 2 Rs.): Report on the Rampur Coal-field:

Vor. XXXIII. Royal 8vo, Pt. 1, 1901 (rice 8 Rs): The Kolar Gold-field, being a descrip-
tion of Quartz-Mining and Gold-Recovery as practised in India. Pt. 2, 1001
(price 2 Rs. ): Reports on some Auriferous localities in India, Art. 1: The
Gold-fields of Wainád. Art 2: Report on the Auriferous Quartzites of Parha-
diah, Chota Nagpur Art. 3: Some auriferous localitiesin North Coimba-

К tore. Pt. 3 (іп the Press): The Geology of the Kalahandi State.

You. XXXIV. Royal 8vo, Pt. 1, 1901 (price т Ке): On a peculiar form of altered Peridotite
in the Mysore State. Pt. 2 (inthe Press): Mica deposits of India. Pt. 3 (in
the Press): Slate Quarrying in Kangra District, Punjab.

Vor. XXXV. Royal 8уо, Pt. 1, 1901 (price 2 Rs.): Geology of Western Rajputana. Pt. 2
(in the Press), No.1, Ona deposit of copper ore near Komai, Darjeeling
District,

° — PAL/EONTOLOGIA INDICA,

(Ser. I, Ш, V, VI, VIIL]—CRE TACEOUS FAUNA OF SOUTHERN INDIA, £y
F. STOLICZKA, except Vor. I, Pt. 1, by H. F. BLANFORD.

Ser. I, & IIL.—Vor. I. The Cephalopoda (1861-65), рр. 216, pls. 94 (б double).
V.—Vor. II. The Gastropoda (1867-68), pp. xiii, 500, pls. 28. .
VI.— Vor. Ш. The Pelecypoda (1870-71), pp. xxii, 537, pls. 50. -

VIII, Vor. IV. The Brachiopoda, Ciliopoda, Echinodermata, Corals, etc. (1872-73),
рр. у, 202, pls. 20. :

(Ser. И, ХІ, ХІ)--ТНЕ FOSSIL FLORA OF THE GONDWANA SYSTEM, by
О. FEISIMANTEL, except Vou. I, Рт. 1, бу Т. OLDHAM and |. MORRIS.

Vor. I, pp. xviii, 233, pls. 72. 1863-70. Pt. 1; Rájmahál Group, Rájmahál Hills. Pt. 2; The
` same (continued). Pt. 3; Plants from Golapili. Pt. 4; Outliers on the
Madras Coast.

Vor. Il, pp. xli, 115, pls. 26. 1876-78. Pt. r,; Jurassic Flora of Kach. Pt. 2; Flora of
the Jabalpur Group. ; 1
Vor. III, pp. xi, 64+ 149, pls. 80 (9 double) (I—XXXI-IA—XLVIIA). 1879-81. РЕ. 1; The

Flora of the Talchir-Karharbari beds. Pt. 2; The Flora of the Damuda and
Panchet Divisions. Pt, 3; The same (concluded).

Nor, ІУ, pp. xxvi 25+ 66, pls. 35 (2 double) (ImXXV+IA—XIVA). Pt. 1 (1882);. Fossil
1 Flora of the South Rewah Gondwana basin. Pt. 2 (1886); Fossil Flora of some
of the coalefields in Western Bengal. ч

(Ser. 1X.)—JURASSIC FAUNA OF КАСН.
Vor. I (1873-76). The Cephalopoda, by W. WAAGEN, pp. i, 247, pls. бо (6 double).
Vor. Il, pt. 1 (1893). The Echinoidea of Kach, by J. W. GREGORY, рр. 12, pls. 2,
Vor. Il, pt. 2 (1900). The Corals, by J. W. GREGORY, pp. 196, I—IX, pls. 26.
Vor. ПІ, pt. т (1900). The Brachiopoda, by Е. L. KITCHEN, pp. 87, pls. 1—15.

Vou. Ш, pt.2 No. 1 (in the Press) Тһе Lamellibranchiata: Genus Trigonia, by Е. L.
KITCHEN. і

(SER. IV.)—INDIAN PRE-TERTIARY VERTEBRATA.

Vor. I, pp. vi, 137, pls. 26. 1865-85. Pt. 1 (1865); The Vertebrate Fossils from the Panchet
rocks, by Т. Н. HuxrLEvy. Pt. 2 (1878); The Vertebrate Fossils of the Kota-
Maleri Group, by Sır P. ре M. Grey EGERTON and І. C. MIALL and
Вглхроквр. Pt. 3 (1879); Reptilia and Batrachia, by К. LyDEKKER. Pt. 4
(1885); The Labyrinthodont from the Bijori group; by R. LYDEKKER.
Pt. 5 (1885); The Reptilia and Amphibia of the Maleri and Denwa groups,
by R. LYDEKKER.

(SER. X)—INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA, dy
R. LYDEKKER, except VoL. I, Рт. 1, фу К. B. FOOTE.

Vor. I, pp. ххх, 500, pls. 50. 1874-80. Pt. 1; Rhinoceros deccanensis. Pt. 2; Molar teeth
and other remains of Mammalia. Pt.3; Crania of Ruminants. Pt, 4; Sup-
plement to Pt. 3. Pt.5; Siwalik and Narbada Proboscidia.

VoL. П, рр. xv, 363, pls. 45. 1881-84. Pt. 1; Siwalik Rhinocerotide; Pt. 2; Supplement to
Siwalik and Narbada. Proboscidia. Pt. 3; Siwalik and Narbada Equide.
Pt. 4; Siwalik Camelopardalide. Pt. 5; Siwalik Selenodont Suina, etc. Pt. 6;
Siwalik and Narbada Carnivora.

Vor. ІП, pp. xxiv, 264, pls. 38. 1884-86. Pt. 1; Additional Siwalik Perissodactyla and Pro-
boscidia. Pt.2; Siwalik and Narbada Bunodont Suina. Pt. 3; Rodents
and new Ruminants from the Siwaliks. Pt.4; Siwalik Birds. Pt. 5; Mas-
todon Teeth from Perim Island. Pt.6; Siwalik and Narbada Chelonia, Pt. 7;
Siwalik Crocodilia, Lacertilia and Ophidia. Pt. 8; Tertiary Fishes.

Vor. IV, pt. 1, 1886. Siwalik Mammalia (Supplement 1), рр. 18, pls. 6.

» » » 2, 1886. The Fauna of the Karnul caves: (and addendum to pt. 1); pp. 40 (19
— 58), pls. 5(vii—xi).
» » м 3, 1887. Eocene Chelonia from the Salt-range; pp. 7 (59—65), pls. 2 (xii—xiii),

(Ser. VII, XIV.)J—TERTIARY AND UPPER CRETACEOUS FAUNA OF WESTERN
INDIA, ûy P. MARTIN DUNCAN ard W.PERCY SLADEN, ex
F. STOLÍCZKA. | P
Vor. I, pp. 16 + IIO + 382 + O1= 599, pls. 5 + 28 + 58 + 13— 104. 1871— 85. PU;
Tertiary Crabs from Sind and Kach. Pt. І (new 2); Sind Fossil Corals and
Alcyonaria, by P. Martin Duncan. Pt. 3. The Fossil Echinoidea of Sind:
Fas. 1, The Саға а beaumonti beds; Fas. 2, The Ranikot Series in Western
Sind; Fas. 3, The Khirthar Series; Fas. 4, The Nari (Oligocene) Series ;
Fas. 5, The Gaj (Miocene) Series; Fas. 6, The Makrán (Pliocene) Series.
Blanford. Pt. 4 The Fossil Echinoidea of Kach and Kattywar, by Duncan,
Sladen and Blantord.

(SER. XIIL)—SALT-RANGE FOSSILS, ûy WILLIAM WAAGEN, PH.D.

Productus-Limestone Group: VoL. І, Pt. 1 (1879) Pisces, Cephalopoda, pp..72, pls. 6.
2 » 2 (1880). Gastropoda and supplement to pt. r, pp. 111
(73-183), pls. 10 (1 double), (vii-xvi).
3 (1881): SE PP- 144 (185-328), pls. 8 (xvii-
XXIV). %
„ 4 (1882-85). Brachiopoda, pp. 442 (329-770), pls. 62
(xxv-Ixxxvi). 2
5 (1885). Bryozoa—Annelide—Echinodermata, pp.
64 (771-834), pls. 10 (Ixxxvii-xcvi).
б (1886). Ccelenterata, рр. 90 (835-924), pls. 20
(xcvii-exvi).
S 3 d » 7 (1887). Coelenterata, Protozoa, pp. 74 (925-98),
pls. 12 (cxvil-cxxviii). .
re from the Ceratite Formation: Vol. II, pt. 1 (1805). Pisces—Ammonoidea, pp. 324,
pls. 40. ;
Geological Results: Vol. IV, pt. 1 (1889), рр. 1—88, pls. 4.
n n ” » 2 (1891), рр. 80--242, різ. 8.

(SER. XV.)—HIMALAYAN FOSSILS.

Anthracolithic Fossils of Kashmir and Spiti: Vol. I, Pt. 2 (1899), by Dr. C. Diener, pp. 96, pls. 8.

The Permocarboniferous Fauna of Chitichun No. I: Vol. I, pt. 3 (1897), by Dr. C. Diener,
pp. 105, pls. 13.

The Permian Fossils of the Productus Shales of Kumaon and Garhwal: Vol. I, pt. 4 (1807),
by Dr. C. Diener, pp. 54, pls. 5.

The Cephalopoda of the Lower Trias: Vol. II, pt. 1 (1897), by Dr. C. Diener, pp. 182, pls. 23.

The Cephalopoda of the Muschelkalk: Vol. II, pt. 2 (1895), by Dr. C. Diener, pp. 118, pls. 31.

Upper Triassic Cephalopoda Faunz of the Himalayas: Vol. III, pt. 1 (1899), pp. by Dr. Von
Mojsisovics, 158, pls. 22.

Trias Brachiopoda and Lamellibranchiata: Vol. ІП, pt. 2 (1900), pp.-76, pls. 12 (including
2 double), -by Alexander Bittner,

Jurassic Fauna : Vol. IV, pt. 1 (in the Press), by Professor Dr. V. Uhlig.

(SER. XVL)—BALUCHISTAN FOSSILS, бу FRITZ NOETLING,; Pn.D., F.G.S.
The Fauna of the Kellaways of Mazár Drik: Vol. I, pt. 1 (1805), pp. 22, pls. 13.

The Fauna of the (Neocomian) Belemnite Beds: Vol. I, pt. 2 (1807), pp. б, pls. 2.
The Fauna of the Upper Cretaceous (Maéstrichtien) Beds of the Mari Hills: Vol. J, pt. 3 (1897),

рр: 79, pls. 23.
(NEW SERIES.)

Тһе Cambrian Fauna of the Eastern Salt-range : Vol. I, pt. 1 (1899), К. Redlich, pp. 14, pl. 1.
Notes on the Morphology of the Pelecypoda : Vol. 1, pt. 2 (1899), Fritz Noetling, pp. 58, pls. 4.
Fauna of the Miocene Beds of Burma: Vol. 1, pt. 3 (1901), Fritz Noetling, pp. 378, pls. 25.
Observations sur quelques Plantes Fossiles des Lower Gondwanas: Vol. II, pt. І (1902).

R. Zeiller, pp. 39, pls. 7.

» n »

n » » n

» n » n

” HI n »

The price бхе2| ог these publications is 4 ansas (б pence) per single plate.

RECORDS OF THE GEOLOGICAL SURVEY OF INDIA, |

Vor. I, 1868.

Part z.—Annual report for 1867. The coal-seams of the Tawa valley. On the prospects of
useful coal being found in the Garrow Hills. Copper in Bundelkund. Meteorites.

Part 2.—On the coal-seams of the neighbourhood of Chanda. Coal near Nagpur. Geological
notes on the Surat collectorate. "The cephalopodous fauna of the South Indian cretaceous
deposits. Lead in the district of Raepur. Coal in the Eastern Hemisphere. Meteorites.

Part 3.—General results obtained from an examination of the gastropodous fauna of the South
Indian cretaceous deposits. Notes on route from Poona to Nagpur тій Ahmednuggur,
Jalna, Loonar, Yeotmahal, Mangali, and Hingunghat. On the agate-flake found by Mr.
Wynne in the pliocene (?) deposits of the Upper Godavery. The Boundary of the Vindh-
yan series in Rajputana. Meteorites. З

Vor. II, 1869.

Part 1.—The valley of the Poorna river, West Berar. Оп the Kuddapah and Kurnool
formations. Geological sketch of the Shillong plateau. On the occurrence of gold in
the district of Singbhoom, &c. Memorandum on the wells now being sunk at the
European Penitentiary, and at the site for the Central Jail, Hazareebagh. Meteorites.

Part 2.—Annual report for 1868. Note on Pangshura tecta and the other species of Chelonia
from the newer tertiary deposits of the Nerbudda valley. Sketch of the metamorphic

Ё rocks of Bengal. .

Part 3.—Preliminary noteson the geology of Kutch, Western India. Contributions to the

geology and physical geography of the Nicobar Islands. e

Part 4.—On the beds containing silicified wood in Eastern Prome, British Burma. Mineralo-
gical statistics of Kumaon division. The coal-field near Chanda. Lead in the Raipur dis-
trict. Meteorites.

Vor. IIl, 1870.

Part 1.—Annual report for 1869. On the geology of the neighbourhood of Madras. On the
alluvial deposits of the Irrawadi, more particularly as contrasted with those of the Ganges.

Part 2.—Geology of Gwalior and vicinity. On the slates at Chiteli, Kumaon. On the lead
vein near Chicholi, Raipur district. The Wardha river coal-fields, Berar and Central Pro-
vinces. Report on the coal at Korba in the Bilaspur district.

Part 3.—The Mohpani coal-field. On the lead-ore at Slimanabad, Jabalpur district. On the
Occurrence of coal east of Chhatisgarh in the country between Bilaspur and Ranchi.
On petroleum in Burma. On the petroleum locality of Sudkal, near Futtijung, west of
Rawalpindi. On the occurrence of argentiferous galena and copper in the district of
Manbhum, S. W. Frontier of Bengal. Assays of iron ores.

Part 4.—On the geology of Mount Tilla, in the Punjab. The copper deposits of Dalbhum and
Singbhum: 1.—The copper mines of Singbhum: 2.—On the copper of Dalbhum and
Singbhum. Meteorites.

Vor. IV, 1871.

Part 1.—Annual report for 1870. Enquiry into an alleged discovery of coal near Gooty, and of
the indications of coal in the Cuddapah district. Mineral statistics of the Kumaon division.

Part 2.—The axial group in Western Prome. Geological structure of the Southern Konkan.
On the supposed occurrence of native antimony in the Straits Setttlements. On the
composition of a deposit in the boilers of steam-engines at Raniganj. On the plant-
bearing sandstones of the Godavari valley, on the southern extension of rocks belonging
to the Kamthi group to the neighbourhood of Ellore and Rajamandri, and on the possible
occurrence of coal in the same direction. í

Part 3.—The progress and results of borings for coal in the Godavari valley near Dumaguden
and Bhadrachalam. On the Narbada coal-basin. Sketch of the geology of the Central
Provinces. Additional note on the plant-bearing sandstones of the Godavari valley.

Part 4—The ammonite fauna of Kutch. The Raigur and Hengir (Gangpur) Coal-field.
Description of the sandstones in the neighbourhood of the first barrier on the Godavari,
and in the country between the Godavari and Ellore. 2

Vor. V, 1872.

Part 1.—Annual report for 1871. Rough section showing the relations of the rocks near
Murree (Mari) Punjab. Mineralogical notes on the gneiss of South Mirzapur and adjoin-
ing country. Description of the sandstones in the neighbourhood of the first barrier on
the.Godavari, and in the country between the Godavari and Ellore.

Part 2—On the geological formation seen along the coasts of Beluchistan and Persia from
Karachi to the head of the Persian Gulf, and on some of the Gulf Islands. Ona tra-
verse of parts of the Kummummet and Hanamconda districts in the Nizam's Dominions.
The geology of Orissa. On a new coal-field in the south-eastern part of the Hyderabad
(Deccan) territory.

Part 3.— On Maskat and Massandim on the east coast of Arabia. An example of local joint-
ing. On the axial group of Western Prome. On the geology of the Bombay Presidency.

Part 4.—On exploration for coal in the northern region of the Satpura basin. Оп the value
of the evidence afforded by raised oyster banks on the coasts of India, in estimating the
amount of elevation indicated thereby. On a possible field of coal-measures in the Godavari
district, Madras Presidency. On the lameta or infra-trappean formation of Central India.
On some recently discovered petroleum localities in Pegu. Correction regarding the sup-
posed eozoonal limestone of Yellam Bile.

Vor. VI, 1873.

Part 1.—Annual report for 1872. The geology of the North-West Provinces.

Part 2.--Тһе Bisrampur coal-field. Mineralogical notes on the gneiss of South Mirzapur and
adjoining country. ECH

Part 3.—Notes оп a celt found by Mr, Hacket in the ossiferous deposits of Narbada valley
(Pliocene of Fa!coner): on the age of the deposits, and on the associated shells. On
the Barakars (coal-measures) in the Beddadanole field, Godavari district. On the geology
of parts of the Upper Punjab. Coal in India. The salt-springs of Pegu.

Part 4.— On some of the iron deposits of Chanda (Central Provinces), Barren Islands and
Narkondam. Stray notes on the metalliferous resources of British Burma.

VoL. VII, 1874.

Part r.— Annual report for 1873. Оп the geological structure of the hill ranges between the
Indus valley іп Ladak and Shah-i-Dula on the frontier of Yarkand territory. On some
of the iron ores of Kumaon. On the raw materials for iron-smelting in the Raniganj
field. On the habitat in India of the elastic sandstone, or so-called Itacolumyte. Geolo-
gical notes on part-of Northern Hazaribagh.

Part 2.—Geological notes on the route traversed by the Yarkand Embassy from Shah-i-
Dula to Yarkhand and Kashgar. On the occurrence of jade in the Karakas valley, on
the southern borders of Turkistan. Notes from the Eastern Himalaya. . Petroleum іп
Assam. Сол! in the Garo Hills. Оп the discovery of a new locality for copper in

the Narbada valley. Potash-salt from East India. On the Geology of the neighbourhood - `

of Mari hill station in the Punjab.

Part 3.— Geological observations made оп a visit to the Chaderkul, Thian Shan range. On
the former extension of glaciers within the Kangra district. On the building and
ornamental stones of India. Second note on the materials for iron manufacture in the
Raniganj coal-field. Manganese ore in the Wardha coal-field.

Part 4.—The auriferous rocks of the Dhambal hills, Dharwar district. Remarks on certain
considerations adduced by Falconer in support of the antiquity of the human race in India.
Geological notes made on a visit to the coal recently discovered in the country of the Luni
Pathans, south-east corner of Afghanistan. Note on the progress of geological investi-
gation in the Godavari district, Madras Presidency. Notes upon the subsidiary materials
for artificial fuel. :

Vor. ҮШ, 1875.

Part t.—Annual report for 1874. The Altum-Artush considered from a geological point of view.
' On the evidences of ‘ground-ice’ in tropical India, during the Talchir period. Trials of
Raniganj fire-bricks. ; ТАУ
Part 2 (out of print).—On the gold-fields of south-east Wynaad, Madras Presidency. Geo-
logical notes on the Khareean hills in the Upper Punjab. On water-bearing strata of
the Surat district. Sketch of the geology of Scindia’s territories.
Part 3.—The Shahpur coal-field, with notice of coal explorations in the Narbada region.
Note on coal recently found near Moflong, Khasia Hills. d 2

Part 4.—Note on the geology of Nepal. The Raigarh and Hingir coal-fields.

Vor. IX, 1876.

Part т (out of print).— Annual report for 1875. Оп the geology of Sind. 3

Part 2.—The retirement of Dr. Oldham. On the age of some fossil floras in India. Descrip-
tion of a cranium of Stegodon Ganesa, with notes on the sub-genus and allied forms.
Note upon the Sub-Himalayan series in the Jamu (Jummoo) Hills.

Part 3.—On the age of some fossil floras in India. On the geological age of certain groups
comprised in the Gondwana series of India, and on the evidence they afford of distinct

zoological and botanical terrestrial regions in ancient epochs, Оп the relations of the .

fossiliferous strata at Maleri and Kota, near Sironcha, C. P.- On the fossil mammalian

faunz of India and Burma.

Part 4.—On the age of some fossil floras in India. On the osteology of Merycopotamus dis-
similis. Addenda and Corrigenda to paper on tertiary mammalia. Occurrence of Ples-
iosaurus in India. On the geology of the Pir Panjal and neighbouring districts.

Vor. X, 1877.

Part r.—Annual report for 1876. Geological notes on the Great Indian Desert between Sind
and Rajputana. On the occurrence of the cretaceous genus Omphalia near Nameho lake,
Tibet, about 75 miles north of Lhassa. . On Estheria in the Gondwana formation. Notices
of new and other vertebrata from Indian tertiary and secondary rocks. Description
of a new Emydine from the upper tertiaries of the Northern Punjab. Observations
on under-ground temperature.

Part 2.—On the rocks of the Lower Godavari. On the ' Atgarh Sandstones’ near Cuttack.
On fossil floras in India. Notices of new or rare mammals from the Siwaliks. On the
Arvali series in North-eastern Rajputana. Borings for coal in India. On the geology

of India.

Part 3.—On the tertiary zone and underlying rocks in the North-west Punjab. On fossil floras
in India. On the occurrence of erratics in the Potwar. On recent coal explorations in
the Darjiling district. —Limestones in the neighbourhood of Barakar. On some forms
of blowing-machine used by the smiths of Upper Assam. Analyses of Raniganj coals.

-Part 4.—On the Geology of the Mahanadi basin and its vicinity. On the diamonds, gold,
and lead ores.of the Sambalpur district. Note on ‘Eryon Comp. Barrovensis,’ McCoy,
from the Sripermatur group near Madras. On fossil floras in India. The Blaini group
and the ‘Central Gneiss’ in the Simla Himalayas. Remarks on some statements in
Mr. Wynne's paper on the tertiaries of the North-west Punjab. Note on the genera

Chceromeryx and Rhagatherium.

Vor. XI, 1878.

Part r.—Annual report for 1877. On the geology of the Upper Godavari basin, between the
river Wardha and the Godavari, near the civil station of Sironcha, On the geology of
Kashmir, Kishtwar, and Pangi. Notices of Siwalik mammals. The paleontological
relations of the Gondwana system. On ' Remarks, &c., by Mr. Theobald upon erratics in

the Punjab.
Part 2.—On the Geology of Sind (second notice). On the origin of the Kumaun lakes. On
a trip over the Milam Pass, Kumaun. The mud volcanoes of Ramri and Cheduba.

On the mineral resources of Ramri, Cheduba, and the adjacent islands.

VT ФОРД

MEMOIRS

OF

THE GEOLOGICAL SURVEY OF INDIA.

MEMOIRS

OF THE

GEOLOGICAL SURVEY OF INDIA.

Мен XXXV BART т.

GEOLOGY CF WESTERN RAJPUTANA, фу Том D. La
TOUCHE, B.A., Superintendent, Geological Survey of
India.

Published by order of the Government of India.

CALCUTTA:

SOLD AT THE OFFICE OF THE GEOLOGICAL SURVEY.
LONDON; MESSRS, KEGAN PAUL, TRENCH, TRUBNER & €o,

MDCC^CCII

GOVERNMENT OF INDIA CENTRAL PRINTING OFFICE; | Kë
S, HASTINGS STREET. `

£N

TABLE OF CONTENTS.

PAGE

CHAPTER L—ÍNTRODUCTION œ . . . с . . I
Previous Observations . . . S ° 3

CHAPTER II],—Puysicat FEATURES . D . Б . : 9
CHAPTER IlI.—SrRATIGRAPHICAL FEATURES (CRYSTALLINE ROCKS) 15
1. Schists and quartzites . С © : О 16

2. Егіприга granite. 5 . . . . 18

3. Malani volcanic series . . о . : 19

4. Granites associated with Malani series - : 24

5. Basic dykes . . . . . o ` 25

CHAPTER 1V.—STRATIGRAPHICAL FEATURES (SEDIMENTARY ROCKS), 26
6. Vindhyan sandstones and limestones Р E 26

7. Boulder beds of Bap and Pokaran (Talchir) . 31

8. Barmer sandstones 5 : з 9 о 33

9. Mesozoic and tertiary strata of Jaisalmir . 34

10. Sub-recent conglomerates 5 С : c 36

CHAPTER V.—RECENT DEPOSITS 6 . E о a . 37
1. Blownsand . о > . o . o 37

2. Kunkur 9 © о . C S o 4t

3. Origin of the salt . - . o e » di
4. Gypsum ` о à 5 о 5 o 43

CHAPTER VÍ.—DETAILED DESCRIPTIONS OF ROCKS b о о 44

1. Atlas of India, Quarter sheet 19 S. Е. o А
2. HI 2 » 20 N. E. . rj 45
3 » » » 528229! 59 0 d 57
4. Barmer area, Rajputana Survey, t in.=2 miles

38 53
Sheet ИСО 197 . . S S c о 74

11 CONTENTS.

PAGE
CHAPTER VII.—PETROGRAPHICAL NOTES 1
1. Malani rhyolites . . . . . . 78
2. Tuffs and breccias . о о a о А 89
3. Granite О S 2 о E . o до
4. Basic dykes . ` o о o © 5 91
INDEX. o : D g o o 6 5 5 © 5 95

LisT OF ILLUSTRATIONS . . . > E > > 402115

MEMOIRS

OF

THE GEOLOGICAL SURVEY OF INDIA.

GEOLOGY OF WESTERN RAJPUTANA, by TOM D. LA
TOUCHE, B.A., Superintendent, Geological Survey of
(паза.

CHAPTER I.—INTRODUCTION.

The Geological Survey of Western Rajputana, of which the present
memoir is the outcome, was primarily undertaken as a continuation
of Mr. R. D. Oldham’s investigations in the years 1885-87 regarding
the possibility of the existence of Gondwana coal measures in Jaisalmir.
The presence of boulder beds of glacial origin at Pokaran and
other places between Jodhpur and Jaisalmir had been noted by
Mr. W. T. Blanford in 1876. These beds were supposed by him to
underlie the Vindhyan sandstones of Jodhpur, but Mr. Oldham found
that similar beds occurring at Bap, about 40 miles north-west of
Pokaran, contained boulders of Vindhyan limestone, and he identified
them as Talchirs, “ the beds which everywhere in India underlie the
coal measures"! The existence of strata of upper Gondwana age had

! Кес. Geol Surv. Ind., Vol. XIX, Ft. 2, p, 123.

2 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

already been noted further to the west in Jaisalmir, and it was
therefore thought that the coal measures of the lower Gondwanas
might be found in the intervening ground. After making a preliminary
examination of the country, Mr. Oldham suggested that borings should
be put down in the area west of Bap, but subsequent investigation led
him to modify his opinion, as he found that there was strong evidence
that. the boulder beds were unconformably overlaid by sandstones of
upper Gondwana age, and that in consequence the existence of the
coal measures in this area was purely a matter of speculation.!

So the matter remained until the year 1896, when 1 was sent to
survey the country to the south of the Jodhpur-Jaisalmir road, the
geology of which was till then only slightly known. So far as the
presence of the coal measures in that direction is concerned, I may say
at once that my investigations have been completely barren of results.
Not only are there no exposures of the Talchir boulder beds to the
south-west of Pokaran, but the country in that direction is so buried
in sand that no rock is visible until the old land surface of the volcanic
rocks in the Barmer desert is reached. All the rocks met with
during my three seasons’ field work, with the exception of the Vindhyan
sandstones of Jodhpur and a few isolated exposures of sandstone of
upper Mesozoic age in the Barmer desert, belong to various crystalline
types. They include schists, quartzites and granitoid gneisses belong-
ing to the Aravalli system, ancient volcanic lavas and tuffs of extremely
acid composition, intrusive granites, and dykes of basic rock.

As regards the rocks that may be concealed beneath the sand, little
or no information is available. Nothing can be learnt from well sec-
tions, for where the wells are sunk close to the hills, as is usually tl.e
case, the rocks pierced by them are naturally the same as those form-
ing the hills themselves, while those that have been sunk further out
in the plain either do not pierce the alluvium or are lined with cement or
otherwise protected to prevent the sides falling in, so that nothing can

` Rec. Geol. Surv. Ind., Vol. XXI, Pt. 1, p. 30.

INTRODUCTION. 3

be seen of the strata passed through. At the same time, the total
absence of any traces of sedimentary rocks on the flanks of the hills
except in Barmer, and the frequent appearance of patches of the crys-
talline rocks among the sandhills, leads me to suspect that the alluvium
generally rests directly upon a platform of the older rocks, and that at
. the time of the deposition of the Gondwanas and marine sediments of
Jaisalmir, the greater part of Marwar must have been dry land.

Previous Observations.

Іп a long paper оп the “ Geology of India" published in the
1854. Journal of the Bombay Branch, Royal Asiatic
Dr. H. J. Carter. Society, Vol. V, Dr. Carter refers! to the presence
of granite in the neighbourhood of Barmer ; to the conglomerate of
Barmer, which he identifies with the “ Greywacke or Steatitic sand-
stone ” placed below the Transition Gneiss in the table given on
page 200 of the paper cited; and to the desert sands, which he con-
jectures are derived from the waste of the “ Punna " or Vindhyan sand-
stone. The lavas projecting here and there from among the sandhills
are considered to be the same Punna sandstones “іп its concrete or
metamorphosed forms;" and the quartzites of the Aravallis are also

referred to the same formation.?
In the same Journal, Vol. VI, Dr. Carter notes the discovery by
1861. Dr. Impey during a journey from Rohri across the
Dr. H. J. Carter. — Jaisalmir desert to Jodhpur, of ammonites at
Kuchri * in Jaisalmir, referred to A. opis, Sow.,a Jurassic (Cutch)
species; and of fossil wood in the sandstones of Lathi, between
Jaisalmir and Pokaran. The ''specimens of clay strata, brick
coloured and green, which had evidently been baked by heat, sent by
Dr. Impey from Jodhpur, were probably fragments of the Malani lavas

occurring near that place.
1 Loc, cit., p. 190.
? [bid, p. 202.
3 Ibid, р. 231.
3 Loc. cit p. 161.

4 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

In the Journal of the Royal Geographical Society, Vol. XL, Sir
1870. H. Bartle Frere gives an account of the physical
Sir H. B, E, Frere. geography of the Ronn of Cutch and its neighbour-
hood, in which he discusses the origin of the sandhills of the Indian
desert. After rejecting the theory that they are built up of blown
sand he ascribes them to the action of earthquakes, and compares
them to the Allah Bund, said to have been thrown up in the Runn by
the earthquake of June roth, 18191 This theory was subsequently
discussed and refuted by Mr. W. T. Blanford in a paper read before
the Asiatic Society of Bengal? It should be remarked, however, that
Sir Bartle Frere’s theory is applied to the longitudinal sand ridges along
the border of the Indus alluvium in southern Sind, and not to the
transverse sandhills of Marwar, and that Mr. Blanford confesses that
he does not quite understand how the former could have been formed
by the prevailing south-west winds.
It is to Mr. Blanford that we are indebted for the first precise
1876. information regarding the geology and physical
W. T. Blanford. features of the Indian desert. Mr. Blanford jour-
neyed from Sehwan on the Indus through Umarkot and Barmer to
Jodhpur and returned to Rohri in Upper Sind through Jaisalmir. He
thus crossed the whole width of the desert in two directions. The
observations made by him were published in two papers, one on the
geology of the country, published in Vol. X of the Records of the
Geological Survey of India, and the other on the physical geography,
including notes on the fauna and flora of the desert, read before the
Asiatic Society of Bengal on 5th July, 1876.8
In the former paper Mr. Blanford gives the following list of the
formations met with during his journey :—*

9. Blown sand

NE Эр T
8. Alluvial deposits 3 ost Tertiary.

1 Loc. ctts D? lors

* Journ. As Soc. Beng., Vol. XLV, Pt. 2, p. 86.
з Journ. As. Soc. Beng., Vol. XLV, Pt. 2, p. 86.
4 Rec. Geol. Surv. Ind., Vol. X, Pt.1, p. 17.

Coq)

‘INTRODUCTION. 5

3
7. Nummulitic limestone а o . . Tertiary.
6. Ammonitiferous beds of Kuchri . . .
5. Jaisalmir limestones and sandstones. 3 Jurassic
4. Barmir sandstones О o . . К
3. Jodhpur sandstones . . ? Vindhyan,
2. Shales and boulder bed of Wows ana Pokran 2
1. Malani felsite, porphyries, syenite, etc. 559

Each of these formations is described in detail. The name of
Malani, from the district of Marwar in which they were first met
with, is given to the volcanic series of porphyritic lavas and ash beds,
which have since been found to be the most widespread rocks in
Jodhpur territory. The occurrence of fragmentary plant remains in
the Barmer sandstones is noted, and these rocks are correlated with
similar sandstones containing fragments of silicified wood occurring
beneath the marine Jurassic beds of Jaisalmir, A list of fossils from
the latter beds is also given.

In the second paper Mr. Blanford gives an account of the phy-
sical characteristics of the desert, with especial reference to the sand-
hills, which he shows are entirely due to the movement of the sands
driven before the prevailing south-west winds, and discusses the
probabilities of a former extension of .the sea over a part of this area,
in order to account for the production of the sand.

Of the papers communicated by Mr. Hacket to the Records of

1880. the Geological Survey there are three which

C. A. Hacket. deal tosome extent with the geology of the area
now described, or its economic resources. The first of these, pub-
lished іп 1880,! is a discussion of the mode of occurrence and origin
of the salt which is the characteristic product of Western Rajputana.
Mr. Hacket thinks that the accumulation of the salt may be accounted:
for by the present operation of drainage and evaporation, but finds
a difficulty in attributing to these causes its local concentration in such
places as the Sambhar Lake, and seems inclined to account for such

1 Rec. Geol. Surv. Ind., Vol. XIII, Pt. 3, p. 197.

6 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

cases by the (entirely hypothetical) existence of deposits of rock
salt of Vindhyan or more recent age concealed beneath the alluvium.

In the same number of the Records! Mr. Hacket gives a list of
useful minerals occurring in the Aravalli region, but the only mineral
mentioned as being found in Marwar is the well known marble
of Makrana, and of Sarangwa, near Desuri in Godwar.

The third paper, published in 1881,? describes the geology of the
Centraland Eastern Aravallis, and of the country lying between the
Aravalli range and the meridian of Jodhpur. Mr. Hacket includes
the whole of the granitic rocks found to the west of the Aravallis
under the comprehensive term “gneiss”. In reality there is no true
gneiss in this area, but there are two protrusions of granite of different
ages, differing widely in texture and composition. |

After describing the sections in the neighbourhood of Sojat, where
upper Vindhyan sandstones are seen resting with total unconform-
ability on the upturned edges of Aravalli schists, Mr. Hacket proceeds
to describe the Malani lavas near Jodhpur and their relations to
the Vindhyan sandstones resting upon them. The existence of a
conglomerate of rolled pebbles of the lavas at the base ofthe Vin-
dhyans is mentioned, and the former are referred doubtfully to the
lower Vindhyan period. A section in the hills north of Chanod is
described in which Malani lavas are seen resting upon some red
slates, supposed to be Aravallis. I have visited this section, which is
the only one where Malanis are found actually in contact with any
rocks older than themselves, and convinced myself that the slates belong
to the Aravalli system and that the relation is one of complete uncon-
formability. This section will be again referred to subsequently.

Two papers were published by.Mr. Oldham in Vol. XIX of the

1886. Records, giving the results of a traverse of

R. D. Oldham. ` Jaisalmir territory undertaken in 1885 with а

1 Rec. Geol. Surv. Ind., Vol. XIII, Pt. 3, p. 243.
2 [bid, Vol. XIV, Pt. 4, p. 279.
% Infra, p. 19.

INTRODUCTION. 7

view to ascertain the probability of Gondwana coal measures being in
existence there. Mr. Oldham identified the boulder beds of Poka-
ran, already described by Mr. Blanford, and those at Bap, with the
Talchirs, and points out that as the sandstones underlying the Jurassic
limestones of Jaisalmir are probably of Mahadeva age, there is a
possibility of the coal-bearing Gondwana beds occurring in the inter-
vening area. The actual presence of these beds can only be ascer-
tained by boring, and Mr. Oldham recommends that borings should
be put down in the country west of Bap. Subsequently in 1887
Mr. Oldham revisited this ground and came to the conclusion that
the boulder beds of Bap were overlaid unconformably by sandstones,
probably of upper Gondwana age, and that any search for coal in
Jaisalmir would be purely speculative,"

In his other paper Mr. Oldham gives an account of the geology
of the country he passed through, with a sketch map and list of the
formations? None of these are found in Marwar, though the lowest,
the Lathi group, containing plant remains and fragments of silicified
wood, was supposed by Mr. Blanford to correspond to the plant
bearing sandstones of Barmer. The group in which the “ Ammonite
bed of Kuchri" of Mr. Blanford occurs is re-named the Abur
group by Mr. Oldham, since the stone is locally known by that

name.
In the same volume of the Records Colonel McMahon published a
1886. description of the microscopical characters of some
Col. McMahon. specimens of Malani lavas, etc, collected by

Mr. Blanford at Barmer, and compared them with the felsites of
'Tusham hill, on the northern border of Bikanir, described in a previous
paper) This is the only information yet available on the petro-
graphy of these interesting lavas.

1 Rec. Geol. Surv. Ind., Vol. XXI, Pt. t, p. 30.

2 Ibid, Vol. XIX, Pt. 3, p. 157.
з [bid, Vol. XVII, Pt. 3, p. tot,

8 LA TOUCHE: GEO! OGY OF WESTERN RAJPUTANA.

In the second edition of the Manual of the Geology of India
1893. several references will be found to the geology of
Manual, and Edition. this region, summarizing the information given

in the foregoing papers. The rocks referred to are the—

Page.
Malani volcanic series . . . о . . a! 9e
Vindhyan sandstones of Jodhpur. . : . . 106
Boulder beds of Bap апа Pokaran . о ° ә e 160
Jurassic rocks of Jaisalmir o - с . о . 226
Nummulitic rocks of Jaisalmir d ы z ; . 308

Distribution and origin of the sandhills ,„ 5 o . 455

PHYSICAL FEATURES. 9

CHAPTER II.—PHYSICAL FEATURES.

The chief physical characteristic of the country under review is
that of a vast sandy plain, in which except when rain is actually
falling, no running water is to be seen, diversified only by the rounded
forms of sandhills, or by isolated knolls and groups of hills composed
of solid rock, whose rugged and barren slopes rise abruptly from the
sea of sand surrounding them. Arid and barren as the country may
seem, however, especially to the traveller who only visits it during the
dry months ofthe winter and spring, it is not altogether a desert in
the strict sense of the term. Wherever water can be obtained from
wells, and whenever, as occasionally happens, there are favourable
rains, excellent crops of wheat and millet are raised, and the
whole country is clothed with a luxuriant crop of grass, affording pas-
turage to large herds of cattle and sheep. The “ desert " thus supports
alarge population, taught by experience to make the most of their
means of subsistence, precarious though they may be, and to store
up the superabundant harvests of the good years for use during less
favourable seasons.

The largest and most lofty group of hills in the country is found
in the Siwana district, to the south of the great bend of the Luni, where
they reach an altitude of over 3,000 feet above the sea. A study of
the map will show that the hills are arranged in irregular groups of
individually isolated peaks or ridges, separated by broad expanses of
sand, in such a manner as to suggest that what we now see are the
highest points of continuous hill ranges, partly buried in sand. In-
deed the hills, viewed from an elevation, resemble nothing so much
as a number of rocky islands forming the crests of a mountainous tract
submerged beneath the sea, and it requires no great stretch of the
imagination to picture this region in some former age as one of flow-
ing rivers and fertile valleys, before some change of climate reduced

the power of the rivers to sweep back the ever increasing encroach-
ment of sand from the south.

10 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

Although running water may in those far off times have played
the chief part in determining the configuration of the hills and ridges,
it is certain that now and for a long time past it must have exercised a
very subordinate influence, and the principal agents of denudation
at the present time are the intense heat of the sun, or rather the
great alternations of temperature that affect the superficial layers of
the rocks during the day and night, and the violent winds that sweep
over the country during the greater part of the year, aided by the
sand they bear withthem. The operations of these agents of denu-
dation have been fully described and explained by Dr. Johannes
Walther in his work * Der Denudation in Der Wüste '',! illustrated
by many examples from the Egyptian desert. Insolation, or the action
of the sun's heat, is explained at page 19 of the work cited, and is
shown to be due to the alternate expansion and contraction of the
outer layers of the rock surface, while the inner layers remain ata
more equable temperature, and do not therefore change in volume.
In Rajputana the results of this action are as conspicuous as they are
in Egypt, and the fragments, especially those of the compact lavas, are
everywhere traversed by fine cracks, the ‘‘halbgesprungene kiesel"
of Walther, due to the same cause, so that when struck with the
hammer they break up into a number of small sharp.cornered frag-
ments, and it is often very difficult to obtain a good hand specimen.
The peculiar half-shattered condition of the boulders of this lava and
other crystalline rocks in the boulder bed of the Salt Range, which
renders them liable, however solid they may be in appearance, to fall
to pieces at a blow from a hammer, may be due to the same cause.

Deflation, or the action of sand laden wind, is described in
Chapter І, section 5, and Chapter 1V, section 1, of the same work.
The peculiar character of the rock sculpturing due to this cause has
been described by Mr. R. D. Oldham? who draws attention to the
difference between the polished surfaces and striae produced in this

1 Kónigl. Sáchsischen Gesellschaft der Wissenchaften, Vol. XVI, No. ІП,

1898.
2 Rec. Geol. Surv. Fnd., Vol. X XI, Pt. 4, p. 159.

бош)

PHYSICAL FEATURES, ІТ

way and the results caused by moving ice. Fxamples of this rock
sculpturing may be seen on the crests of any of the rocky hills in
Merwar exposed to the prevailing winds, and especially clearly on
the smooth surfaces of the glassy Malani lavas (Pl. I, fig. 1) The pro-
cess, in the case of the more highly porphyritic lavas, is assisted by
the decomposition and weathering out of the felspars, whereby a
pitted surface, giving the rock a vesicular aspect, is formed, affording
the sand blast a continually renewed, roughened surface to work on.

The undercutting ard polishing of isolated masses of granite is
another instance of the effects of deflation (РІ I, fig. 2), and the large
hollows frequently seen in the cliffs of granite and lava may be partly due
to the same cause ; tut these hollows probably owe their origin more to
the weathering out of concretionary masses in the case of the granite,
or, in the case of the lavas, to the presence of large gas pores. In both
cases the hollows are probably only enlarged and polished by the
wind. The hard bands of sub-recent conglomerate often found in the
river beds are sometimes affected in a curious way. Where they rest
upon softer sands the latter are cut away from under them by the
wind, leaving oblong masses of the conglomerate, which are frequently
tumbled about at all angles (Pl. I, fig. 3). lf these masses were sub-
sequently covered up with silt or sand and the whole consolidated and
afterwards denuded, the geologist of the future might have some diffi-
culty in understanding how such large masses of apparently transported
conglomerate came to be heaped together in a bed of sandy silt, and if
he were a glacialist, might be strongly tempted to call them erratics,
and ascribe their position to the agency of floating ice or glaciers!

Acting as they do on rocks of varied composition and texture,
these agents of denudation produce results of very different appear-
ance. The highly inclined schists and quartzites of the Aravalli
system are formed into long hog-backed ridges with an equal slope of
talus on either side ; the undulating sheets of Malani lava form conical

hills or long ridges with steeply scarped sides and rugged contours,

(шк)

12 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

with a talus of exceedingly sharp angular fragments at the foot of the
scarps (Pl. ІП, fig. 1); the more homogeneous bosses of intrusive
granite have their outer surface stripped off in concentric layers and
form hummocky domes with steeply sloping smooth sides, while
since the granite fragments are quickly broken up by the action of
the weather into a loose gravelly sand, little or no talus is formed at
the foot of the hills composed of this rock (Plates VI-VIIT) ; and lastly
the almost horizontal sandstones are carved into level plateaux, sur-
rounded by almost vertical scarps, wherever they rise to any appre-
ciable height above the plain. It is thus possible to form an opinion
of the character of the rocks of which any particular hill consists,-
even from a considerable distance, by observation of its form and the
appearance of the talus slopes at its foot.

A peculiar feature in several parts of the country, especially in
those where the blown sand is not in great quantity, is the occurrence
at the base of each isolated rocky peak or knoll of a gently sloping
“ glacis " extending to a distance of a mile or more from the foot of the
hill, Sections of these “ glacis" are exposed in great numbers in the
numerous water-courses, dry except during an actual fall of rain,
which radiste in all directions from the hill, and cut deep channels
in the deposit Their substance is seen to consist principally of a
calcareous tufa or “kunkur” frequently consolidated into bands of
considerable thickness, mingled with sand and fragments of the rock
composing the hill, in fact, a natural concrete. The kunkur gradually
diminishes in thickness towards the outer edge of the “glacis” and the
slope gradually fades off into the surrounding plain. The sand on the
level is also frequently impregnated with nodular kunkur, as may be seen
in the wells, but except near the hills this accumulation of calcareous
matter does not rise above the general level, and the formation of the
** glacis’’ is evidently connected in some way with the presence of the
hill. I shall refer to the source of the carbonate of lime from which this
kunkur is formed later on in the chapter dealing with the blown sand.!

! Infra, p. 41.

PHYSICAL FEATURES. 13

Little need be said here about the process of formation of the sand-
hills, which has often been described and explained! I have not
had an opportunity of seeing the longitudinal type of sandhill, found
along the western edge of the desert in the Thar and Parkar district
of Sind, but many of those that occur in the parts of the desert visited
by me are of an intermediate type. Several of these are well shown
on the one-inch maps of the neighbourhood of Balotra? They ap-
“pear to have been formed from hills of the transverse type by wind
denudation, the wind having scooped out furrows along the wind-
ward slope of the dunes. Inthe Barmer desert the sandhills are all
of the transverse type and well illustrate the tendency that dunes
possess of remaining permanent when they have reached a certain
height, for these dunes are all large, rising to 150 or 200 feet above
the plain, and have evidently, judging from the size of the trees
growing on their leeward slopes, remained in their present position for
many years. Further to the north-east, to the west of Jodhpur and
in Bikanir, the sandhills are not so high, and are constantly in motion
during the monsoon, but I have had no .opportunity of studying their
motion during that period.

The rivers of this region play a very subordinate part in moulding
the surface features of the country. None of them, even near the
hills, contain perennially running water, and the beds of all of them are
so choked with sand, that the water, when floods do occur, exercises
little or no eroding action on the solid rock. The Luni is the prin-
cipal river, taking its rise in the Ana Sagar at Ajmere and traversing
the whole of Marwar till it loses itself in the sands at the head of the
Runn of Cutch, It receives many tributaries from the Aravallis to
the south-east of its course, but none of any size from the more sandy
c ountry to the north,

1 Blanford. Journ. As. Soc. Beng., Vol. XLV, Pt. 2, p. 86.
Walther. Denudation in der Wüste, Chapter V.
Vaughan Cornish. Journ. Roy. Geo. Soc., Vol. IX, p. 288.
? Rajputana Survey, Sheets 71, 72.

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14 LA TOUCHE: GEOLOGY OF WESTERN КАЈРОТАМА.

It seems not improbable that the depression in which the salt
deposits of Pachpadra are collected is a portion of an old bed of the
Luni. Near the town of Pachpadra and again lower down where the
Luni makes a sudden bend to the south there are traces of the bed of
a large river indicated on the one-inch map, and even now when
the river is in flood it spills over the northern bank above Tilwara and
flows towards the Pachpadra depression, but is prevented from flood-
ing it by sandhills.

There seems little doubt that within quite recent times the flow
of water down these rivers must have been much greater than it is
now, and that the change is due to an alteration in the climate.
Nearly all the rivers contain masses of subrecent conglomerate, formed
of well rolled pebbles and boulders of various crystalline rocks em-
bedded in a calcareous sandy matrix. The conglomerate is always in
horizontal layers, exposed in the banks and beds of the rivers and
sometimes filling cracks and fissures in the older rocks. These pebbles
and boulders must have been transported at a time when the flow of
water was much greater than it is now, for the present rivers, even in
times of flood, are able to move little more than fine sand and gravel,
and only just round off the corners of such fragments of rock as do
find their way into them.

If the sand that now chokes the lower courses of the rivers were
cleared out, the velocity of the water in the rivers would no doubt be
increased, and its power of erosion and of rounding pebbles and trans-
porting them would be proportionally enhanced. At the same time the
sea would occupy a large portion of the valleys, the Runn of Cutch,
for instance, even without any subsidence of the valley floor. This
change would no doubt have a great effect on the climate and the
rainfall inland would be greatly increased. А gradual silting up of
the river valleys, combined with the progressive encroachment of the
blown sand, would account for the change to the present arid condi-
tion of the country.

! Rajputana Survey, Sheet 71.

(450)

STRATIGRAPHICAL FEATURES. 15

CHAPTER III—STRATIGRAPHICAL FEATURES.

(CRYSTALLINE ROCKS.)

With the exception of the schists and quartzites of the Aravalli
system, which are only found along the eastern border of the area
under discussion, and are everywhere vertical or highly inclined to
the horizon, the rocks met with have suffered very little disturbance
since they were first formed, a circumstance which adds considerably
to the difficulty of working out their relations with each other, for
many of the isolated exposures exhibit only one variety of rock,
entirely cut off from all visible contact with those that may be asso-
ciated with it, by the surrounding sand. As before mentioned, nearly
the whole of the rocks seen are crystalline, and can only be distin»
guished from each other on petrological and stratigraphical grounds.
The only fossiliferous rocks in the whole of Marwar are the sandstones
of Barmer, and the age of these even is a matter of doubt, since the
fossils, which almost without exception are plant remains, are in so
fragmentary a condition that it is difficult to form any definite conclu-
sions from them.

It is impossible in the present state of our knowledge of the crys-
talline formations of India to identify the crystalline rocks of Marwar
with those of other localities, and just as the region is sharply cut
off by its climate and aspect from the remainder of India, so the
geology must be regarded for the present as peculiar to this area. Їп
fact, the most widespread formation that occurs here, the volcanic
lavas and tuffs of the Malani series, are so far as is yet known, cone
fined strictly to this part of the country, and have no representatives
in other parts of India.

The formations represented are given in the following table, the

( 15)

16 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

Jodhpur area including the whole of the country between the eastern
edge of the Barmer desert and the Aravallis :—

PERIOD. Jaisalmir (Oldham). Barmer. Jodhpur.
Recent .| Blown sand and allu- | Blown sand and | Blown sand- and allu-
vium. alluvium. vium.

К N. River conglomerate.

Sub-recent . | Amir shingle beds .

Teritary .| Nummulitic limestone

Barmer sandstone
(P cretaceous).

Abur group e А
Parihar sandstone .
Mesozoic .4 | Bedesir group o
Jaisalmir group А

سس

Lathi group ° ES
Unconformity. E А
Boulder beds of Bap and $ Boulder beds of Bap
Pokaran (Та!єһїг). 8 and Pokaran (Tal
8 chir).
ә
Unconformity. Unconformity.
Limestones c ;
Paleozoic Sandstone (Vindhyan) Sandstones ] Vindhyan.
| Unconformity,
Malani Volcanic | Malani Volcanic series,
series.
Unconformity.
Schists and quartzites
(Transition).

Intrusive rocks.

Siwana granite I in Malani
Jalor granite series.

Erinpura granite. Intrusive in transition
schists,

I. Schists and Quartzites (Delhi System р).
The schists and quartzites, already mentioned as occurring only
in the eastern portion of the region under review, are very poorly
represented, and the outcrops they furnish are so isolated and frag-

nientary that it is impossible to form a definite opinion as to the
(16)

STRATIGRAPHICAL FEATURES. 17

order of succession of the strata. So far as І am able to express an

opinion, judging from the published descriptions, they appear to

belong to the Delhi system as restricted in the second edition of the

Manual! They consist of dark grey micaceous schists, or schistose ,
slates, with thick lenticular beds of white or bluish white quartzite,

the latter often forming hills of considerable size, in which the quartz-

ite is the only rock visible. The strike of the whole series is from

north-east or north-north-east to south-west or south-south-west,
parallel to the main range of the Aravallis, and they are always very
highly inclined or vertical. Along the foot of the Aravalli range, in

the district of Godwar, these rocks contain bands of calcareoue

schist which, when in contact with intrusive granite, has become

altered into a white crystalline marble. A large mass of this occurs
at the village of Sarangwa, about four miles west of Desuri, and is
largely quarried for building purposes. The marble rests upon a
large dome-shaped boss of granite, a portion of the large spread of that
rock which occupies the ground between the base of the hills and
Erinpura. A lenticular fissure containing large rhombohedral crystals

of calcite or Iceland spar was recently discovered among the calca-

reous schists in the hills about seven miles south-east of Sadri, near

Desuri in Godwar. Some of the crystals are fairly transparent, but none

are without flaws, and the bulk of them are too opaque to be of any

value,

The famous marble quarries of Makrana are situated in exactly
the same position as regards the range, but are about 140 miles to the
north-west of Sarangwa. Неге the marble forms bands very con-
stant in width, in micaceous and calcareous schists with a north-
north-east—south-south-west strike and very high easterly dip. The
rocks form a series of low ridges parallel to each other, separated
by level stretches of blown sand. There may be only one band of
marble repeated by folding. The bands of marble alone are worked

1 Manual, Geology of India, 2nd edition, p. 68.
С)

18 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

out, leaving, in the centuries that have elapsed since the quarries
were first opened,a series of deep narrow chasms, partly filled with
débris and sand. The marble varies a good deal in texture, some
portions being fine grained and translucent, while the grain of other
portions is much coarser. The beauty of the carved work fashioned
from this marble is well known. Here also the alteration of the rock
into marble is apparently due to the intrusion of a coarse granite,
veins of which penetrate the schists in the direction of the strike.

2. Erinpura Granite,

To the west of the main range of the Aravallis, in the district of
Godwar, the low ground is occupied by a great spread of an exceed-
ingly coarse granite, which stretches as far west as the hills north of
Erinpura, but is not found further west than this. To the south it
extends into Sirohi, and may be easily recognised along the railway
to the south of Erinpura by the rounded hummocky knolls into which
it has weathered (Pl. VIIT). The felspar crystals in this granite are fre-
quently three or four inches in length, and the other constituents,
quartz and mica, are in proportionally large crystals. Where the
granite is in contact with the schists, it assumesa gneissose character
and is foliated along lines parallel to the junction, but that it is really
intrusive is proved by the irregularity of the boundary, by the fact that
the granite throws off veins into the schists, that it includes fragments
of the latter, and that in some cases, as for instance the marble of
Sarangwa referred to above,the rocks in contact with it have been
altered. Near the junction with the schists the included masses of the
latter have been rolled out into lenticular patches and add to the
foliated appearance of the granite; the large felspars are drawn out
into lenticular “ eyes " surrounded by films of mica and the rock has ће
appearance of a true gneiss. But at a distance from the boundary,
the felspars are arranged in no definite direction, and possess well

(18)

STRATIGRAPHICAL FEATURES, 10

defined prismatic outlines, and the granitic nature of the rock is
apparent.

The eastern boundary of this spread of granite runs along the
foot of the main scarp of the Aravalli range in the district of Godwar
and it does not appear to extend into the hills. The boundary is
probably a faulted one, but it is always concealed by débris from the
hillss It was mapped by Mr. Hacket as gneiss, but he seems to have
been in some doubt as to its true character and relations with the
true gneiss of the Aravalli system.!

3. The Malani Volcanic Series.

After the intrusion of the coarse granite of Erinpura just described,
a censiderable length of time must have elapsed during which both
the schists and granites were folded under enormous pressure and after-
wards largely denuded before the next series ‘of rocks was deposited
upon their upturned edges. Only one instance has yet been dis-
covered of a visible junction between the schists and the overlying
bedded lavas.

The section is exposed in a valley lying about two and a half miles
to the south-west of the village of Miniari and seven miles north of
Chanod in the district of Pali? It is mentioned by Mr. Hacket,
who says that “а small thickness of red shales dip under the Malani
porphyries ; but I am unable to say if they are Arvalis or not. These
hills are quite isolated in the plain; the nearest hills of gneiss are
at Kaunla, about eight miles to the south, and the nearest Arvalis
about eighteen miles to the south in the large hills north of Erin-
рша,” А diagrammatic representation of the section is given in
fig. 4, Pl. I.

The floor of the valley is occupied by reddish slates or shales which
are either vertical or have a very high dip to the south-east. The

! Rec Geol. Surv. Ind., Vol. XIV, Pt. 4, p. 298.
? Rajputana Survey, Sheet. 115.
3 Кес, Geol. Surv. Ind., Vol. XIV, Pt. 4, р. 302.

dc NS qp

20 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

lavas are bent up into an anticlinal, the axis of which runs north and
south, and the flows rise in steep scarps on either side of the valley
On the west side, at the base of the scarp, a band of conglomerate
some 20 feet thick is interposed between the lavas and the slates,
resting on the upturned edges of the latter. The boulders and
pebbles in this are frequently well rolled and consist of quartzose
grit, quartz, schist and slate, evidently derived from the underlying
slaty series. The strike of the slates is fairly steady, from north-east
to south-west, the lavas and associated beds passing transgressively
across their edges, and the evidence of unconformability is very com-
plete. Onthe east side of the valley the slates appear to dip beneath
the lavas and the conglomerate is not visible, but the ground iscovered
with talus and thorny scrub. The angle of dip of the two series of
rocks is however quite different, and at the north end of the valley on
this side the lavas are again found resting directly upon the upturned
edges of the slates. I found several exposures of micaceous schist
with exactly the same strike as these slates, in the plain to the east of
this section, and I have no doubt that the slates do belong to the Ara-
valli series.

At one or two places to the north of this, v72., on the western edge
of the group of hills at Khairla, a station on the Jodhpur railway to
the north-west of Pali, and again at Rajpura on the left bank of the
Luni, about half way between Khairla and Jodhpur, nearly vertical
slates are seen within a few hundred yards of outcrops of the Malanis,
and in these instances the lava sheets are quite unconformable both in
dip and strike to the older rocks. Mr. Hacket says that the schists
at Khairla are “ undoubted Arvali rocks.”

The lavas of the Malani series are for the most part rhyolites of a
highly acid type, varying greatly both in colour and texture. The
most common variety is of a rich brown colour tinged with red or pur-
ple, with a stony texture and studded with porphyritic crystals of pink
or flesh coloured felspar and minute blebs of quartz. Other colours, such

( 20 )

STRATIGRAPHICAL FEATURES. әт

аз bright red, blue, green, dark grey ог black are common, and а few
are white or light grey. Sometimes the porphyritic crystals are
altogether absent. The lavas are all highly siliceous and so hard that
the unweathered surface cannot be scratched by a knife. In spite of
the great age of these rocks, and of any alteration they may have
undergone, there is clear evidence that when originally formed they
were true volcanic ejectamenta, spread out over the surface of what
was probably dry land or the shores of a shallow lake or sea, All the
well known characteristics of glassy lavas can be observed in them. Some
of the flows show beautifully developed flow-structure, and in many
the original glassy texture has hardly undergone any alteration, so that
a thin slice remains almost dark under the microscope between crossed
Nicols. Perlitic structure, one of the most certain indications that
the rock was originally a true glass, can be detected in a few cases, and
spharulitic structure is very common, ranging from the most micros-
copic examples up to nodules an inch or more in diameter, A vesi-
cular structure is not often met with, but it does occur in some of the
flows ; the vesicles are often filled with secondary minerals, forming
amygdales.

In many places the lavas are interstratified with thick beds of tuff
and breccia formed out of the dust and fragments of the lavas them-
selves, and evidently due to volcanic explosions. Some of the tuff beds
show signs of having been rearranged under water. But the most cone
clusive evidence for the subaerial character of the volcanoes is afforded
by the presence of bands of conglomerate, formed of well rolled
pebbles of the lavas, intercalated between the flows in many places.
These bands have all the appearance of ordinary river gravels, and
prove that at certain times during the period of volcanic activity sub.
aerial denudation was acting upon the lava flows already solidified.

The lavas and associated rocks cover a very large area in Jodhpur
territory, extending from a little east of the meridian of Jodhpur to the
edge of the desert between Barmer and Sind, or 145 miles from east

( 2r )

22 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

to west, and from Pokaran in the north to Jalor in the south, a distance
of 120 miles. The area over which they are found thus amounts to
about 17,000 square miles. They have hitherto not been identified with
certainty beyond the limits ofthe Jodhpur State, though there is no
doubt that rocks closely resembling them occur in other parts of India:
Some similar rhyolites, occurring at Tusham hill, about 240 miles to
the north-east of the nearest outcrop of the true Malanis near Jodhpur,
have been described by Colonel McMahon.

'The conditions under which the lava sheets are now exposed, in iso-
lated hills and ridges often separated by miles of sand-covered ground,
render it impossible to make out any regular sequence among them,
пог сап any estimate be formed of the Total thickness of the volcanic
series. There are no indications whatever of the presence of the vents
from which the lavas were poured out, except in one doubtful instance
which will be referred to subsequently. The slight amount of distur-
pance they have undergone has not been sufficient to bring the base of
the series to the surface except in one locality,? and the vents,
whether these were in the form of fissures from which the lavas welled
out and consolidated on either side, or pipes of the Vesuvian or Puy
type, are buried beneath the accumulation of lava, or may perhaps be
concealed beneath the sand. Ifthe vents were filled towards the
close of the volcanic period with loose material, it is quite likely that
they would have suffered denudation more rapidly than the hard sheets
of lava surrounding them, and their sites would be covered with alluvium
and sand. With regard to the nature of the vents, there does not
appear to be any concentric arrangement of the lava sheets, such as,
even in the fragmentary state in which they are exposed to view, we
might expect to find if they had been ejected from a centre of eruption,
andit is therefore more probable that they were of the fissure type.

1 Rec. Geol. Surv. Ind., Vol. XVII, Pt. 3; p: ror. Vol, XIX, Pt. 3, p. 101.

2 Infra, p. 51.
à Supra, p 19,

( 22 )

Si КАТІСКАРНІСАЇ FEATURES. 23

That the eruptions were accompanied by explosive outbursts is proved
by the intercalation of tuffs and bands of breccia, produced by the
shattering of previously consolidated flows, among the bedded lavas.

The viscid character of such acid lavas as these, when they were in
a liquid state, is often well exhibited by the uneven and scoriaceous
aspect of the surface of the flows, and by the abrupt manner in which
they frequently die out. Some of the sheets are of considerable thick-
ness and extend without any alteration in appearance for several miles,
but very often а scarp can be seen to be built up of a number of
thin sheets, differing from each other in colour and texture. A colum-
nar structure is frequently well developed in them, and also serves to
distinguish the different sheets, building up a scarp, from each other.

There are indications that during this period the eruptions were
not altogether ofan acid character. In several places sheets of igneous
rock of a more basic type, containing plagioclase felspar and no free
quartz, are interbedded with the rhyolites. It is difficult to say
whether these are truly interbedded lavas or whether they are sills thrust
in between the sheets of rhyolite after the consolidation of the latter.
The material of which they are composed is much more subject to
decomposition than that of the rhyolites, and as a rule their relations
with the latter are obscured by soil and débris. They sometimes
appear to be intrusive, but in other cases the appearance of inter-
stratification is quite as clear. On the whole I think that the balance
of evidence is in favour of their being intrusive.

The tuffs.and breccias associated with the lavas are quite subordi-
nate in amount to the latter, so far as can-be seen from the limited
exposures now visible. It is quite possible thata great part of the
sandy plains between the hills of lava may be underlaid by these softer
rocks, which are as a rule exposed only in the slopes at the base of
the scarps formed of the harder lavas, The tuffs are usually dis-
tinctly stratified, but the breccias are generally found in small patches
only, enclosed between sheets of lava. The bands of pebbly conglo-

(1239)

24 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA,

merate intercalated in places between the lava flows are sometimes
associated with tuffs, but elsewhere they are sandwiched in between
two flows of lava without the intervention of any finer material.

4. Granites associated with Malani Series.

Closely connected with the outpouring of the lavas there are other
signs of volcanic activity in the intrusion, both into the Aravalli
schists and the lavas themselves, of great masses of granite. The granite
is generally coarse grained, but not nearly so much so as the Erinpura
granite described akove, and is lithologically of two varieties. One of
these contains quartz in abundance, pink or white felspar, and horn-
blende, but no mica. This is the “ syenite ” of Mr. Blanford. The other
variety contains the same minerals, but with the addition of mica. The
latter, which I have named the Jalor granite, since it is well developed
in the neighbourhood of that town, which is built at the foot of an
enormous boss of this granite, is confined to the eastern edge of the vol-
canic area, where it forms a succession of large bosses, either surrounded
by highly inclined Aravalli schists, or in a few cases in contact with
the lavas, in which it is seen to be intrusive. The other variety, with-
out mica, is confined to the interior of the volcanic area. It forms the
greater part of the enormous mass of the Saora range, south of Siwana,
rising to over 3,000 feet above the sea, and several other bosses formed
of it are found in that neighbourhood. I have, therefore, named it the
Siwana granite. It also forms several hills in the Barmer area, and it
is found to the south-west of that district on the borders of the
Runn of Cutch, in the Kalinjur hills of Nagar Parkar, where it has been
described by Mr. Wynne.! In the Barmer area the relations of the
granite to the lavas are not so clear as elsewhere, for although there is
evidence that the granite was intrusive in the lava sheets in contact
with it, the former is also traversed by dykes of a rock indistinguish-

1 Mem. Geol. Surv. Ind., Vol. IX, Pt 1, pp. 48, 98.

STRATIGRAPHICAL FEATURES. 25

able from the lavas, which must have been injected after the consoli-
dation of the granite. The granite must have been intruded after a
sufficient depth of lava had accumulated to allow of the crystallisation
of the material in a coarse grained form, but before the extrusion of the
lavas had ceased. The granites may, therefore, be considered as
strictly contemporaneous with the lavas, and it is not at all improba-
ble that they mark the approximate sites of some of the vents or
fissures from which the latter were poured out.

5. Basic dykes.

The volcanic period was succeeded by the intrusion into the
complex of lava and granite of а number of basic dykes, the
material of which is an altered olivine dolerite or diabase consisting
of plagioclase felspar, olivine and augite with a small amount of
biotite. The interval that elapsed before the intrusion of these dykes
cannot be ascertained, but it must have been sufficient to allow of the
development in the lavas and granites of joint planes, since the dykes
usually follow such planes. The majority of the dykes run north and
south, but another system crosses these almost at right angles. There
does not seem to be any difference in composition between the rocks
of each system. "They appear to have been injected before the de-
position of the overlying Vindhyan sandstones, since they have not
been found traversing these, but as it happens, none of the dykes
were observed, even among the lavas, in that part of the country
where the remnants of the sandstones are now visible, and it is quite
possible that the dykes are of post-Vindhyan age, Mr. Blanford
mentions an outburst of * basalt" in connection with the Talchir
boulder beds of Pokaran, but he says that the relations of the rocks
are not clear.!

1 Кес, Geol. Surv. Ind., Vol. X, Pt. 1, p. 13.

(-25- )

26 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

CHAPTER IV,—STRATIGRAPHICAL FEATURES.
(SEDIMENTARY ROCKS.)

6. Vindhyan sandstones and limestones.
The relations between the Vindhyan sandstones and the schists of
the Aravalli series is, as might be expected, one of complete uncon-
formability. A section of the junction occurs at Sojat, where
Mr. Hacket thus describes it." “The Sojat hills are formed, at base,
of nearly vertical Arvali slates, capped by about 10 to 20 feet of a
conglomerate composed of small pebbles of quartz, very nearly hori-
zontal, or with a dip of 3° to north, passing up into a fine white and
reddish sandstone, of which there may be about roo feet in thickness.
On the northern side of the hills are some beds of chert resting upon
the sandstone, and which in the large hills a mile to the north passes
up into a thick limestone. The sandstone resembles very closely
the Kaimur sandstone, and doubtless the whole, from the conglomerate
upwards, may be referred to the Upper Vindhyan series.”

Still further north, at Khatu, a similar section of the unconform-
able junction between the schists and sandstones is exposed, but
here there is another band of conglomerate with overlying sandstones
between the Kaimur sandstone and the limestone. This second
band of sandstone is referred by Mr. Hacket to the Bhander sub=
division, and is stated to be upwards of 200 feet thick. The middle
(Rewa) group of the Upper Vindhyans is absent.

After the eruption of the Malani lavas a considerable period of
time may have elapsed before the sandstones of the Vindhyan system
were deposited upon them. The evidence of unconformability is not
so clear as in the case of the junction between the schists and sand-
stones, for as it happens the sandstones are never seen in contact with
the lavas in places where the latter have been disturbed, but wherever
the two formations occur together they are both nearly hori-

1 Rec. Geol. Surv. Ind., Vol. XIV, Pt. 4, p. 300.
( 26 )

STRATIGRAPHICAL FEATURES. 27

zontal. On the other hand there is clear evidence that the lavas were
subjected to a long period of erosion and weathering before the
deposition of the sandstones. In the scarps north of the city of
Jodhpur numerous sections of the junction are exposed, in which the
sandstones are seen to rest upon a very uneven floor of the lavas.
This in itself would not be evidence of unconformability, for the
surface of the lava flows was probably originally irregular and
hummocky, as is usual with'such viscous lavas as these, but the sand-
stones can sometimes be seen banked up against denuded and scarped
edges of the flows. Moreover, at the base of the sandstones there is
frequently a layer of varying thickness in which large blocks of the
lava are imbedded in silt and grit (Pl. II, fig. 1). These are not water-
worn boulders, transported from a distance, but are always of the
same variety of lava as that composing the sheet immediately under-
lying them, and they have evidently been weathered out Zw situ,
and then quietly buried in silt. Again, the upper portion of the lava
flows, where they are exposed beneath the scarps of sandstone, is
usually found to be weathered to a considerable depth, so that the
lava has become quite soft and rotten. "This weathering of the surface
ofthe lavas is not observed where they are not protected by the
sandstone, and evidently took place before the latter were deposited,
and judging from the effects of atmospheric agencies on the lavas at
the present time, it must have taken a very long period to produce
the results noted on such slowly altered rocks as these. Lastly, in a
few places patches of true conglomerate, containing waterworn and
well rolled pebbles and boulders of the lavas, mingled with pebbles of
other crystalline rocks, and transported from a distance, are found
occupying hollows in the uneven surface of the lava flows, and under-
lying the sandstones. These are associated with beds of fine red and
green shales also of quite local occurrence.

Whatever may have been the length of the interval separating the
period of the emission of the lavas from that of the deposition of the

(275)

28 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

Vindhyans there is no doubt that an entire change of conditions took
place during it, and that from this time onwards this region, which
had in former times been the scene of intense volcanic activity, became
subjected only to those slow changes of level which have resulted in
the gradual accumulation of a series of sedimentary rocks. The oldest
of these are sandstones, passing upwards into impure cherty lime-
stones, and the whole group from its resemblance to the Vindhyan
sandstones and limestones on the eastern side of the Aravalli range
has been referred to that period. The position of the group with
reference to the undoubted Talchir boulder beds of Bap and Pokaran
renders it impossible that it can be other than Vindhyan.

At Jodhpur the thickness of the sandstones does not exceed 200
feet, but they have been subjected to great denudation, and the upper
portion of the beds has been everywhere removed. In this neighbour-
hood they dip very gently towards the north, and gradually disappear
beneath the plain, and the isolated groups of hills further north
probably consist of higher beds of the same series. At Pokaran,
where they are exposed close to the Talchirs, but not visibly in
contact with them, the boundary is probably a faulted one.

The sandstones consist of rapid alternations of more or less fine
grained gritty material, generally tinged with red, but sometimes
grey or white. Strings of waterworn pebbles of quartz, none of
which are of large size, frequently occur, especially in the higher
portion of the beds, and with the presence of current or false
bedding, which is very conspicuous in the artificially scarped
cliffs near Jodhpur, and the numerous examples of ripple marking,
which is beautifully developed on the surface of some of the finer
beds, indicate that the sandstones were laid down in shallow
water. Some of the finer beds make a most excellent building
stone, universally employed in Jodhpur and the neighbourhood.
Not only are the walls of the houses built of it, but pieces of
sufficient length in proportion to their thickness are obtained and
used as beams for the roof, while thinner slabs are used for the

( 28 )

STRATIGRAPHICAL FEATURES. 29

ceilings. Thus except for doors and windows no wood whatever is
employed in the construction of the houses, no slight advantage in a
country where wood fit for timber is so scarce. The same stone is
also capable of being fashioned into the beautiful carved work with
which the larger houses and palaces in Jodhpur are embellished, the
soft reddish colour of the stone adding greatly to the effect of the
delicate tracery of the window screens and other ornaments. No one
who has seen the interior of the Fort at Jodhpur will readily forget
the impression made at once by the massive character of the buildings
and the delicacy of the carved screens and cornices so lavishly
employed in their ornamentation, and it is difficult at first to realise
that the same material can be turned to such different uses.

The occurrence of two bands of conglomerate in these sand-
stones near Sojat and Khatu, already referred to," points to the
existence of a shore line in the direction of the Aravalli range at the
time of their deposition. Mr. Oldham has already pointed out? the
resemblance between the relations of these beds to the Vindhyans on
the eastern side of the Aravallis and those of the recent deposits on
the northern flanks of the Himalayas with the Indo-Gangetic alluvium.
There was apparently no connection whatever between the basins of
deposition on either side of the range, and in the absence of fossil
evidence it is only on lithological grounds that we can correlate the
successive beds in these separate areas with each other. All we can
say is that towards the end of the Vindhyan period a local depression.
was formed in the western side of the Aravallis, in which these sand-
stones and limestones were deposited. It is impossible to say how
far this basin extended in a north-westerly direction, for the rocks on
that side are concealed beneath the Jurassics of Jaisalmir and the
sands of the desert. To the south and south-west it did not extend
apparently as far as Balotra or Barmer, for in that direction sand-
stones of much later age rest directly upon the Malanilavas. But

1 Supra, Pp. 26.
2 Manual, Geology of India, 2nd Edition, p. 106.

30 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

to the north-east, parallel to the Aravalli range, the basin extended,
at least at intervals, as far as Khari, 40 miles to the north-east of
Bikanir, and 150 miles from the present southern limit of the sand-
stones near Jodhpur. (

So far these rocks have yielded no traces of indubitable organie
remains, but in the neighbourhood of the village of Osia, 30 miles
north of Jodhpur, I found on the lower surface of some of the fine
grained sandstone beds at a particular horizon, certain markings
which I find it difficult to reconcile with any other than an organic
origin. They are evidently casts of grooves on the upper surface of
the underlying beds, but the latter appear to have been of a soft
clayey nature and all trace of the actual grooves has disappeared..
The casts are in the form of straight or curved ridges, occasionally
duplicated, with a rounded cross section, very slightly raised above
the surface of the slabs on which they occur and about one-eighth
of an inch in width. They are sometimes parallel, but frequently
cross each other in all directions. The resemblance of the straight
ones especially when they tail off gradually at the ends, as they often
do, to mechanically formed striz, is very striking, and it is possible
that they may have been produced by some mechanical means, but it
is very difficult to conceive what the agent can have been. They are
certainly not worm tracks; they are not such markings as would be
made by large grains of sand or small pebbles, besides no such
pebbles are to be found in the beds in which they occur. Floating
vegetation just grazing the bottom; the tips of fronds of algae or
reeds sweeping to and fro under the influence of gentle currents in
shallow water; or possibly the fins of fish swimming within a short
distance of the bottom are explanations that have suggested them-
selves to me, but none of them are satisfactory, especially because
if the markings were due to either of these causes we should certainly
find traces at least of the vegetation or of the fish preserved in these
fine grained sandstones, and a diligent search has revealed absolutely

(SoD

STRATIGRAPHICAL FEATURES. 31

nothing of the kind. For the present, therefore, the origin of these
mysterious markings must remain undecided.

7. Boulder beds of Bap and Pokaran (Taichir).

The next group of beds in succession to the Vindhyans has already
been alluded to several times; these are the boulder beds exposed at
Bap, Pokaran and other places on the eastern borders of Jaisalmir.
I have not met with these beds in any part of the area surveyed by
myself, but they are described by Mr. Blanford as consisting of
“ green, red and variously coloured shales, occasionally soft, but often
hard and even porcellanic. Some are fine, others are coarse and
sandy, and contain grains of pink felspar, and of a green mineral
resembling epidote; some beds being composed throughout oí one
or the other of these minerals. Jn places, pebbles and boulders of
the Malani porphyries and syenite are found towards the base of
these shales; the boulders being occasionally from three to four feet
in diameter, whilst remains of much larger blocks, which had fallen
to pieces, but which could not have measured less originally than
twelve to fifteen feet in diameter, were seen about Lowo.. These
boulders appear to have been brought from a distance, and there is
some reason for supposing that they may have been transported by
ice, as the underlying surface of the Malani porphyries near Pokaran
was іп one instance found to be grooved and striated.” !

These beds were supposed by Mr. Blanford to underlie the
Vindhyan sandstones, and Mr. Oldham was at first of the same
opinion, but 40 miles to the north-east of Pokaran, near the village of
Bap, exactly similar beds are seen, but containing, in addition to
boulders of the Malani lavas, pebbles derived from the Vindhyan
limestone, which must therefore have been indurated and metamor-
phosed before the accumulation of the boulder beds,? The difficulty

1 Rec. Geol. Surv. Ind., Vol. X, Pt. 1, p. 17.
2 Rec. Geol. Surv, Ind, Vol, XIX, Pt. 2, p. 123.

32 LA TOUCHE: GEOLOGY OF WESTERN КАЈРОТАМА.

of supposing that two exposures of such similar beds, separated by
so short a distance horizontally, should belong to such different
periods as pre and post-Vindhyan, makes it almost certain that the
boulder heds at Pokaran are faulted down against the Vindhyans, The
sandstones of the latter formation form a scarp rising above the low
ground in which the boulder beds are exposed, and the apparent
superposition of the sandstones on the Talchirs may be due to masses
of the sandstone having slipped bodily down the scarp. |

Mr. Oldham describes the boulder beds of Bap as consisting of
“а matrix of fine grained marl through which fragments of felsite,
syenite, limestone, gneiss and granite of all sizes from a few inches
to in one case over 10 feet across, are scattered; and many of these
are smoothed and striated in the peculiar manner characteristic of
glacier work."! These beds extend from Shekasar to Nokra, both
villages near the eastern boundary of Jaisalmir, a distance of about
35 miles.

Another instance of a boulder bed of probably the same age may
be mentioned here, since it contairis boulders of the Malani lavas and.
granites, though it occurs far beyond.the limits of the area now dealt
with. This is the well-known boulder bed of the Salt Range in the
Punjab, which has been shown to be of upper Paleozoic age and to
rest unconformably and transgressively on all the older Palaozoic
strata of the range? Mr. Middlemiss has described microscopically
several specimens of the boulders from this bed, and though he cou'd
not specifically identify any of his specimens with the few examples of
Malani rocks available, he notes the existence of a certain family
likeness between them.’ These boulders were probably carried across
from what must have been the high glacier covered land of the Malani
area by floating ice.

1 Loc. sit.

2 Manual, Geology of India, 2nd Ed., p. 120. Rec. Geol. Surv. Ind, Vok
SN Vou bite U

з Ibid, Vol. XXV, Ре, I, p. 29.

( 32

STRATIGRAPHICAL FEATURES. 33

8. Barmer Sandstones.

The only strata of later age than the Talchirs, excepting recent
deposits, that occur in the area I have personally examined, are the
plant bearing sandstones of Barmer, mentioned by Mr. Blanford.!
These rocks consist of whitish and grey sandstones locally indurated
and breaking with a conchcidal fracture, but sometimes soft and veined
or blotched with purple or red. At the base is a thick band of con-
glomerate, the pebbles in which are well rolled and are all derived from
the underlying Malanilavas. Some of the sandstones are locally slightly
calcareous. The beds dip to the north-east at angles of 20° to 25° and
near the town of Barmer form a narrow fringe along the margin of the
hills of lava. A small outlier of the conglomerate occurs at the top
of a conspicuous conical peak about a mile north-west of the town,
rising to about 500 feet above the plain and 1,387 feet above sea level.
Patches of a similar sandstone, surrounded by sand and alluvium,
occur at intervals for about 18 miles to the north and there are others
on the eastern side of the Barmer desert not far from the Luni. Here
they rest directly upon an uneven floor of the lavas. At Barmer
the sandstones are extensively quarried for millstones and building
purposes.

The upper limit of the sandstones is concealed by the alluvium of
the plain, and nothing can be seen of the overlying beds, A fine
unctuous clay or fuller’s earth, which may overlie the sandstones, is
found at Kapuli, a village about 12 miles to the north of Barmer, and
is quarried for sale as “ Multani mitti." It may be of lower Tertiary
age, for the same substance is found and quarried to the north-east in
Jaisalmir and Bikanir territory and is there associated with nummu-
litic limestones.

I spent several days at Barmer in attempting to collect more well
preserved fossils from the sandstones than had hitherto been obtained.

It is impossible to get perfect specimens as the sandstones will not
1 Rec. Geol. Surv. Ind., Vol. X, Pt. 1, pp. 11, 18.
(2537)

34 LA TOUCHE: GEGLOGY OF WESTERN RAJPUTANA.

split along definite bedding planes, and all the fossils 1 obtained are
in a more or less fragmentary condition. One specimen appears to
be part of the cast of a Unio shell, but the hinge is absent; I also
found another small fragment of a bivalve shell, which may be a Car-
dium. Тһе most interesting plant remains obtained are two im-
pressions of veined leaves, which are undoubtedly dicotyledonous
angiosperms and, so far as they go, indicate that the beds are not
older than cretaceous. But, further to the north-east on the borders
of Jaisalmir, there is a group of sandstones containing fossil wood
and plant remains which Mr. Blanford considered to be on the same
horizon as the Barmer sandstones, and which Mr, Oldham found to un-
derlie the marine Jurassic beds of Jaisalmir. Mr. Blanford distinctly
states that these sandstones, named the Lathi group by Mr. Oldham,
contain «dicotyledonous fossil wood, and we must either suppose
that in this region dicotyledonous plants appeared at an earlier stage
of geological history than they do in Europe, or that the sandstones of
Lathi de not really underlie the Jurassic strata of Jaisalmir but are
faulted against them, or that the latter are not really Jurassic, but
belong to a higher stage among the Mesozoic strata. So little is as
yet known of the paleontology of these Jaisalmir rocks that the
question must be left unsettled for the present. It should be stated,
however, that among the fossils collected by Mr. Blanford from the
Jaisalmir limestones, the group supposed to overlie the Lathi sand-
stones, several were determined by Dr. Fiestmantel, who found that
they were characteristic Jurassic forms, occurring in the Chari group
of the Cutch Oolites.!

9. Mesozoic and Tertiary strata of Jaisalmir, -
The strata of Mesozoic and Tertiary age succeeding the Talchir
boulder beds in Jaisalmir have been described by Messrs. Blanford

and Oldham, but their relations and paleontology have not been

! Rec. Geol. Surv. Ind., Vol. X, Pt. 1, p. 19.

STRATIGRAPHICAL FEATURES. 35

worked out in detail. Except the Barmer sandstones with their frag-
mentary plant remains, none of these newer rocks occur in the area
I have examined myself. No large scale maps of Jaisalmir territory
have been published, even the sheets of the Atlas of India being as
yet a blank as regards that part of the desert, and in the absence of
such maps, especially where the exposures of rock are so isolated, no
detailed work can be done. Mr. Oldham has given a sketch map of
part of the country lying to the north of Jaisalmir, and divides the

rocks into the following groups! :—
ي‎ SE

Period. Name of groups. Description,
Recent . . | Alluvium and Blown
sand.
Sub-recert о | Amir shingle beds. . | Patches of rolled pebbles of local origin; possibly

marine littoral deposits.

Tertiary . . | Nummulitic . . . | Limestones with nummulites апд beds of Fuller’s
earth (Multani mitti),

Abur group . . . | Sandstones, shales and fossiliferous limestones,
the latter weathering dark red (* Ammonite bed
of Kuchri’’}. Am. (Stephanoceras) opis, Sow,
Arca, etc.

| Parihar group . | Soft white felspathic sandstones, occasionally
| calcareous and sometimes ferruginous, locally
hard and glassy, weathering into a clean sugary
sand.

|

| Bedesir ртоцр o . | Purplish and reddish sandstones with thin layers
of black vitreous ferruginous sandstone; a bed
Мезәгоіс 2 of red calcareous sandstone contains fossils
resembling Katrol (Cutch) forms,

Jaisalmir group . Thick bands of compact buff and light brown
| limestone interstratified with grey, brown and
| blackish sandstone with some conglomerate.
Probably equivalent to the Chari (Cutch) group,
Ат. (Stephanoceras) fissus, Sow., Nautilus
Kumagunensis, Waagen, Terebratula biplicata,
Sow., Corbula lyrata, Sow., C. pectinata, Sow.,
etc.

| Lathi group . S . | White, grey and brown sandstones interstratified

with numerous bands of hard black and brown

| ferruginous sandstones and grit. Towards the
base soft argillaceous sandstone, streaked and
blotched with purple Fragmentary plant re-
mains and pieces of dicotyledonous wood.

EE i ee
! Rec, Geol. Surv. Ind., Vol, XIX, Pt. 5, p. 137.

(7457)

36 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

10. Sub-recent conglomerates,

These conglomerates have already been described in a previous
chapter. They evidently belong to a period when the drainage of
the country followed the same lines as it does now, but when the
conditions of climate were such that the flow of water in the rivers
was much greater than it is at present. The conglomerates are
found in the channels of the Luni and of all its tributaries from the
Aravallis, but only in patches, as they have undergone a considerable
amount of denudation by winds and floods.

1 Supra, p. 14.

36

RECENT DEPOSITS. 37

CHAPTER V.—RECENT DEPOSITS.

1. Blown sand.

The most widespread and important of the recent formations of
Western Rajputana is undoubtedly the blown sand with which so
large a portion of the country is covered. Driven by the south-
westerly gales which blow across the desert for several months in the
year, and unimpeded in its advance by streams of running water, it
has encroached upon the land until no district is entirely free from
it, except those lying immediately at the foot of the Aravalli range,
where the numberless watercourses descending from the hills,
although they contain running water for only short periods, are able
to sweep back the sand blown into them.

The dunes that are formed in the open plain are all of the trans.
verse type, that is, they present a broad gently sloping face to the
south-west, and a steep slope, corresponding with the angle of eee
of the sand, to the north-east. A plain covered with these sandhills,
such as that to the north-west of Pachpadra, presents a curious aspect
when viewed from the top of one of the rocky hills to the east, in the
evening, when the sun is sinking towards the western horizon. The
steep face of each sand dune casts an intensely black shadow, while
from the elevation on which one is standing the lower ground appears
as a uniform level, so that the country presents the appearance of a
yellow plain crossed by a number of black bars, parallel to each other,
the cause of which is not at the first glance very evident.

Where, as is often the case, the sandhills are formed under the
lee of one of the rocky knolls, they form long ridges extending in a
north-east direction. The sand is also banked up against the wind-
ward side of the hills, and sometimes rises to a great height, over 800
feet in the case of those at the western end of the Saora range, above the
plain. Butas a rule they do not actually reach the slopes of the hills,

(BID

38 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

but are separated from them by a deep ravine kept clear by the
drainage from the hill sides, and probably to some extent also by
eddies of wind. When, however, the drainage is thrown off to either
side by a rocky spur, the sand runs up to the rock and forms a
gently sloping ramp on which one may climb the hill without having
to scramble over the loose angular talus with which the lower slopes
are covered. "These sloping ramps of sand perform a certain amount
of work in distributing the rock débris falling from the hill sides, the
creep of the sand carrying the fragments outwards and downwards.
Thus they are sometimes transported to considerable distances from
the hill, much in the same way that a moraine is carried by a glacier.

The sand of which the dunes are formed presents several features
of interest. That which is found in the dunes out in the plain, where
the sorting action of the. wind has had full play, is very uniform in
grain, the diameter of the individual grains averaging about one-fifth
of a millimetre, though much of the sand is still finer than this. But
on the lee side of ouicrops of solid rock, especially of the sandstones
and granites, a greater variety of size is observed. For example, on
the north side of the broad plateau of sandstone north-west of Jodh-
pur, in the neighbourhcod of the village of Teori, the ordinary fine
yellowish buff sand of the dunes is mingled with grains derived from
the sandstones, easily distinguishable from the former by their bright
red colour. Owing to their size and weight these grains have a
tendency to collect along the crests and in the furrows of the ripple
marks formed by the wind, and their strongly contrasting colour gives
a peculiar streaky appearance to the surface of the ground.

` The composition of the sand, judging from numerous samples
collected from widely separated localities, appears to be very uniform.
Quartz grains predominate, and flakes of hornblende and felspar, as
well as chips of the lavas are common. All of these might be derived
from the rocks locally present in the desert, and it is a significant fact
that flakes of mica are very rare and appear to be almost confined to

( 38

RECENT DEPOSITS. 39

those samples which were collected near the eastern margin of the
desert where there are outcrops of micaceous schists and granites.
The rocks in the interior of the desert, on the other hand, the Malani
lavas ard Siwana granite, do not contain mica, and its absence from
the sand, contrasted with the presence in abundance of the minerals
that are found in these rocks, is almost complete proof that the sand
has mainly been derived from local degradation of the rocks, and has
not, or at any rate the bulk of it, been transported from outside the
desert area.

At the same time there is very good evidence that the sand is not
entirely of local origin, but that some of it has travelled from a con-
siderable distance. In all the samples that I have collected, including
localities so far apart as those south of Barmer and north-east of
Bikanir, there is an appreciable quantity of particles of carbonate of
lime which cannot have been derived from any of the local rocks.
Their amount varies from less than one per cent. in the sand from
Bikanir to as much as ten per cent. by weight in some of the samples
from the south-west, or from 251b to over 3 cwt. per ton of sand.
But the most interesting point about these particles is that many of
them are casts of the shells of minute foraminifera, and this fact
affords a clue to their origin. I found that they were not the shells
of recent foraminifera blown up from the coast, but that they are in a
fossilised condition, for when tbey are immersed in weak acid on a
glass slip beneath the microscope, they dissolve away gradually,
becoming smaller and smaller till at last nothing is left, and it is
evident that they are solid all through. І then examined a few speci-
mens of Tertiary limestones that had been collected in Cutch by
Messrs. Wynne and Fedden, and found similar foraminifera in some
of them, especially in a limestone almost entirely made up of frag-
ments of nummulites and other foraminifera, labelled as occurring
“ North of Kannai, north-east of Teyrah, probably on the horizon of
the Gaj (Miocene) group of Sind." The specimen in the museum

(1399)

40 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

from this bed (No. 3:285)! is coloured a bright yellow by iron oxide,
and many of the foraminifera found in the sand have a similar colour.
Most of these interesting little fossils are flatly coiled shells probably
belonging to the genera Rotalia or Pulvinulina, but they have not yet
been accurately determined. I think that there can be little doubt that
these particles of carbonate of lime have actually been carried by the
winds from Cutch and distributed over the desert. The most distant
locality to which I have traced them is Khari, до miles to the north-
east of Bikanir and 500 miles from Cutch. Here they are exceedingly
minute and are not recognisable as foraminifera, but that is not to be
wondered at, considering that they have travelled so far in com-
pany with hard grains of quartz and other minerals.

I found, on examining samples of the sand from several localities
with the microscope, that the great majority of the grains show little
or no signs of attrition, and are in fact for the most part as sharp and
angular as when they were broken off the parent rock. The contrast
between the effects of water and wind action is well brought out in
the sample from Teori, referred to above, in which the ordinary dune
sand is mingled with grains derived from the plateau of Vindhyan
sandstone to the south. Тһе latter are easily recognisable under the
microscope by their bright red colour, and are all well rounded, having
been derived from an aqueously formed sandstone, whereas the grains
of dune sand are mostly quite angular. Such sand as this could never
form beds of sandstone with well rounded grains, like the “ millet
seed” Triassic sandstones in England, which have been attributed to
the action of wind.?. No doubt the fact that the grains of sand, when
driven by the wind, are all moving in the same direction with a more
or less uniform velocity, coupled with the minuteness of the grains,
which must make the effect of any collisions that may take place

1 This number refers to the entry in the Rock Register of the Indian
Museum. 7

2 See the discussion on a paper by Mr. Vaughan Cornish. “ On the forma-
tion of sand dunes." Geographical Journal, Vol, IX, p. 302.

( 40 )

RECENT DEPOSITS. 41

between them while in the air very slight, accounts for the small
amount of attrition that they undergo. The persistence of the parti-
cles of carbonate of lime and foraminifera among grains of hard
material like quartz to such great distances as I have indicated also
shows that the amount of attrition that goes on must be very small.

2. Kunkur.

1 have already mentioned! the almost universal occurrence of
thicks bed of calcareous tufa or kunkur among the desert sands, and
shown how they are apt to collect round the bases of the isolated
rocky knolls scattered over the country. At first sight the source
of the lime in these deposits was not at all obvious, for the lavas,
granites, and other crystalline rocks round which they collect do not
contain lime in any appreciable quantity. But the discovery of the
particles of carbonate of lime and foraminifera in the sand at once
afforded an explanation of the origin of these deposits. Occasional
showers of rain falling upon the sand dissolve these particles and,
since the moisture is quickly evaporated, the lime is soon re-deposited
as tufa. Naturally this process goes on most rapidly where the rain
water is collected on a rocky surface and flows off into the surround-
ing sand; and thus the gently sloping “glacis” at the bases of the
knolls, described in Chapter II, are formed.

3. Origin of the Salt.

It is a well known fact that the sand and alluvium of the Rajputana
desert is more or less impregnated with salt. Except after heavy
rain the water that lingers in a few pools here and there along the
course of the Luni is intensely salt, and large quantities of it, of
immense commercial value, are obtained from brine pits situated in
various depressions in the general surface of the plain, the largest
of which occurs near Pachpadra, or from salt lakes like those at

1 Supra, p. 12.

(ағ)

42 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

` Sambhar and Didwana. The water of wells that are sunk in the
sand without reaching the rock beneath is also brackish as a rule,
and sometimes decidedly salt. Mr. Blanford conjectured that the
salt may have been derived from an arm of the sea which, he supposed,
formerly extended up the valley of the Luni,’ but there are consider-
able difficulties in the way of accepting this theory. Ia the first place
there is no evidence whatever of a recent submergence and re-eleva-
tion of the desert area, such as would bring the Sambhar lake down
to sea level, and back again to its present position 1,184 feet above
the sea. This objection was pointed out by Mr. Blanford himself.
Again, if the sea only extended as a gulf up the lower portion of the
Luni valley, this would not account for the presence of salt higher up
the valley; and in any case such a gulf, if it ever existed, would be
filled up by ordinary silt brought down by the rivers from the hills,
and not more likely to contain salt in larger quantities than similar
sediments elsewhere.

It seems to me that instead of our being compelled to speculate
on former extensions of the sea or great changes of level, no evidence
of which is to be found, in order to account for the presence of the
salt, a simple explanation presents itself in the peculiar conditions of
the country as regards drainage and evaporation. The rain water
flowing from the hilis is evaporated long before it reaches the sea,
owing to the porous nature of the sand and the dryness of the atmos-
phere, and the salt it contains, which would under ordinary condi-
tions be carried by rivers irto the sea, and help to swell the amount
of salt already there, is deposited among the sand grains, and in
process of time has thoroughly impregnated the soil with salt. The
process is in fact exactly similar to that which, it is universally
admitted, accounts for the presence of the salt in the sea itself.
Wherever depressions in the general level of the country occur, as at

1 Journ. As. Soc. Beng., Vol. XLV, Pt. 2, p. 96. Rec. Geol. Surv. Ind., Vol.
Ee
(22)

RECENT DEPOSITS. 43

Pachpadra, Sambhar, and other places, the drainage from the sur-
rounding higher ground concentrates the salt, until in course of time
the accumulation has become so great as to be commercially
valuable.

It is perhaps not improbable that as particles of carbonate of lime
are distributed over the desert by winds blowing from the south-west,
and in time form beds of kunkur, so also particles of salt may be
blown up from the sea shore and help to increase the amount of salt
contained in the sand.

4. Gypsum.
in several places in the desert, on low lying ground surrounded by
sandhills, beds of impure gypsum of considerable extent are found.
A large deposit of this kind occurs on the plains about half way
between Barmer and Madpura, on the Balotra-Barmer railway. It
probably owes its origin to a process similar to that which has resulted
in the accumulation of the salt, being gradually leached out from
the sand and deposited when the water dissolving it evaporates.
The gypsum is locally known as “Kuddi” and is extensively used

as a cement for lining the interior of wells.

44 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

CHAPTER VI.—DETAILED DESCRIPTIONS OF ROCKS,

When the exposures of the rocks are so isolated from each other
as they are in Western Rajputana, the usual method of describing
their relations in detail, by following the belts of outcrops of the
various strata across the country, is hardly practicable, and I have
thought it more convenient to take each quarter sheet of the atlas of
India on the scale of 4 miles to the inch, covering the area surveyed,
separately, and describe the rocks found in it, noticing any points
worthy of remark in the sections exposed.

I. Quarter sheet то ©. Е,

The greater part of the area included in this quarter sheet is covered
by blown sand and alluvium. At the western edge about Lawa (Lowo)
the Talchir boulder beds are exposed, along the foot of a scarp of
Vindhyan sandstone. Several detached outcrops of the Vindhyans
occur between this place and Teuri near the south-east margin of the
map. They either just show above the surface of the ground between
the sandhills or rise into scarped hills and plateaus of no great height.
Several large groups of these hills occur in the neighbourhood of Osia,
about 12 miles north of Teuri. The sandstone scarps rise abruptly
to a height of 100 to 150 feet above the plain, and the base is always
concealed by sand. The peculiar striz-like markings described in
Chap. IV, p. 30, were found among these hills between one and two miles
south-east of Osia, near a small village named Basin, not marked on
the map.

Several small inliers of the Malani rhyolites occur among the sand-
stones forming the plateau west of Bastua, near the southern edge of
this quarter sheet, and others are isolated among the sandhills near
Кеш, to the west of the same plateau. The largest of these inliers
occurs in a narrow gorge immediately above the southern village of
Bastua. The lava has the appearance of a ridge or hummock that has

АА

DETAILED DESCRIPTIONS OF ROCKS, 45

been gradually buried by the sandstones, which are quite horizontal.
There is no conglomerate at the junction,

2. Quarter Sheet 20 N. E.

Along the northern margin of this quarter sheet the Vindhyan
sandstones form several plateaus of considerable extent, the largest of
which stretches for several miles to the north and west of Jodhpur. To
the west they are found as far as the neighbourhood of Shergarh,
where they gradually disappear beneath the sand. At Balasar,
11 miles north-east of Shergarh, the sandstones rest horizontally upon
& very uneven surface of the Malanis, and the junction can be traced
along the scarps to the north and south of the village. Here also
there is no conglomerate atthe base of the sandstones. The junction
is also exposed along the scarps to the north of Chaunda, 16 miles
north-west of Jodhpur, and is of a similar character.

The former extension of the sandstone plateau over the whole area
is well shown by the number of detached conical flat topped knolls
scattered over the plain. Several good examples of these “ witnesses ”
(Zeugen) may be seen near the village of Ghoriala, a few miles east of
Balasar (РІ. 11, fig. 2).

At Jodhpur the Malani lavas form a large flattened dome-shaped
mass extending for about five or six miles to the west of the city and
surrounded by scarps of the Vindhyan sandstones. Patches of true
conglomerate containing rolled pebbles and boulders of granite and
other crystalline rocks, are exposed at the base of the sandstone in a
shallow valley west of Chopasni, about five miles west of Jodhpur, at the
base of Masuria hill about a mile south-west of the city, and at the base
of a scarped outlier about half a mile to the south-west of the old Resi-
dency at Sursagar. Here it is associated with some finely laminated
purple shales, containing globular patches of a white substance resem-
bling kaolin, which give a peculiar mottled appearance to the surface
of the laminz. This substance is apparently derived from the

(25590)

46 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

decomposition of grains of felspar imbedded in the shales. Markings
resembling the casts of rain prints also occur on some of the laminae.
The boulders are sometimes imbedded in the shales, which are then
contorted on a small scale. None of the boulders in the conglomerate
are of very large size, but some of the granite blocks reach a foot in
diameter. There is nothing to indicate that they may not have been
deposited by ordinary fluviatile action in a hollow on the lava surface.
The thickness of conglomerate exposed here is from 20 to 25 feet at
the most. At the base of Masuria hill there are about 40 feet of red
shales at the base of the sandstones.

The psuedo conglomerates mentioned in Chap. IV, p. 27, are well
exposed along the scarp to the north-east of Sursagar and again to
the north of Mandor, four miles north of Jodhpur. The blocks of lava in
these always correspond in composition and texture with the lava of
the sheet immediately beneath them. Where this has a tendency to
weather into rounded concretions the boulders are also rounded
(РІ. 11, fig. т), but elsewhere they are quite angular.

From the village of Baorli, 19 miles to the west of Jodhpur, a
series of detached hills of Malani lavas runs in a south-west direction
as far as the village of Thob, 12 miles north-west of Pachpadra, a
distance of about 30 miles. The highest of these rise to an eleva-
tion of between goo and 1,000 feet above the sea, and about 300 feet
above the general level of the plain. Between them the ground is
usually at a slightly higher level than. the sandy plain to the east and
west, and is covered in many places with a fine angular gravel, derived
in situ from the weathering of the lavas. The chain of hills is prob-
ably, therefore, composed of the highest points of a continuous ridge of
EE the lower portions of which have been smothered in sand.

The hill at Baorli is composed of earthy looking brownish red
rhyolite, with porphyritic crystals of pink felspar, mostly kaolinised.
There seem to be several flows, one of which, forming the crest of a
low ridge immediately south of the village, consists of a light green

( 46%)

DETAILED DESCRIPTIONS OF ROCKS. 47

and pink compact rhyolite without porphyritic felspar, but containing
humerous minute grains of quartz. The flows have an undulating
westerly dip of about 10°.

The greater portion of the groups of hills at Agolai, eight miles south-
west of Baorli, is composed of a strongly porphyritic rhyolite, dark grey
or reddish brown in colour, with rather fresh looking crystals of felspar
and numerous grains of quartz, in fact the most common type of Mal-
ani lava. Some of the flows exhibit a fairly well marked columnar
structure, especially at the base of the peak (g12 ft.) close to the
village of Dugar. Flowestructure is not uncommon, and is especially
well developed in a small hill at the south-west end of the group, the
upper part of which consists of a rock strongly resembling pitchstone.
This flow is inclined to the south-east at about 32°. The usual dip
of the beds in this group of hills is to the north or north-east, at
angles varying from horizontality up to 45?. At the south-eastern edge
of the group is a bed of vesicular lava also exhibiting flow-structure,
associated with some greenish ash beds dipping N. E. at 10°. Another
variety of rhyolite is seen in the low hills near Agolai on the western
edge of the group; this is a compact greyish red rock, with very few
porphyritic crystals. Near the top of the peak close to Dugar, on the
north side, a patch of breccia is intercalated with the rhyolites, consisting
of angular fragments of rhyolite imbedded in a dark coloured, matrix.
Some other brecciated beds are seen on the slopes along the southern
edge of the group, but these appear to be flows of rhyolite broken
; up iz sttu, probably by movements іп the mass when partly solidified,
and re-cemented; the fragments only show on the weathered surface
of the rock and are not visible in section.

Between Agolai and Korna, six miles to the south-west, there are
several low rises consisting of the reddish brown porphyritic rhyolite
and covered with angular gravel derived fromthe disintegration of the
rock zz situ. At Korna there are three or four small hills, the upper por-
tion of which consists of thick flows of rhyolite dipping at a low angle

(4227)

48 LA TOUCHE: GEOLOGY OF WESTERN RAJPULANA.

in a northerly direction. Flow-structure is well developed in this rock
and is very conspicuous on the weathered surfaces. The edges of the
flows present a steep scarped face to the south and exhibit a well
defined columnar jointing, at right angles to the surface of the flows.
The rhyolites rest upon a series of buff coloured felsitic tuffs and ash
beds, which are exposed on the slopes of the hills below the scarps, and
also dip slightly towards the north. Some of these beds are distinctly
fragmental, the fragments being imbedded in a glassy felsitic paste.
Others have a bright green colour mottled with specks of red hematite
and are apparently largely composed of chloritic mud.

The large hills, rising to go2 feet, about four miles to the south-west
of Korna, are mainly composed of strongly porphyritie rhyolite, with a
dark purplish colour. A small knoll at the northern end of the group
consists of compact glassy rhyolite with well developed flow-structure,
containing fragments, sometimes up to three or four inches in diameter,
of a previously consolidated flow of a similar rock, but darker in colour.

A short distance further to the south-west, in the neighbourhood of
Nagona, an interesting series of rocks is exposed. The large hill,
937 feet high, immediately to the south of the village, is composed of a
glassy looking rhyolite, which splits up easily along vertical plains, which
are seen to be lines of flow, causing the rock to be almost as fissile as
ordinary slate. On the top of tke hill these divisional planes are seen
in plan to pursue a wavy direction, generally about north-west to
south-east and sometimes flowing round an included mass of more,
massive porphyritic rock. In the surrounding hills patches of a similar
fissile rock are frequently met with, among the nearly horizontal
flows of more porphyritic rhyolite of which the main mass of the hills
is composed, and rise through the latter after the manner of an
intrusive dyke. There is nothing to indicate that there has been any
great disturbance of the rocks since they were poured out, or that the
fissile rock was originally horizontal; and it seems therefore very

probable that the vertical character of the flow-structure is due to

( 48 )

DETAILED DESCRIPTIONS OF ROCKS. 49

pressure, from the sides of a great fissure through which the rock was
erupted, and that this may be the site of a vent. The fissile rock
extends over an area of about six miles in its longer diameter from
N. W. to S. E., but it may extend to a greater distance beneath the
sand and alluvium beyond the edge of the hills; the width seems to be
very irregular, from two to three miles.

At the south-west extremity of this group of hills a thick lava
flow shows a strongly developed columnar structure, with lines of
flow running transversely to the columns. A section across the end of
a spur formed by this flow shows that the columns are arranged ina
roughly radial fashion, lying nearly horizontally towards the side of the
spur and inclined at various angles towards the centre, like the radial
structure so often seen in dykes of basic rock, Some of the columns
are traversed by joints showing a cup and ball structure.

In the dry watercourses at the western edge of these hills a
breccia occurs formed of clips and fragments of glass imbedded ina
glassy matrix. The process of devitrification in the imbedded frag-
ments is very well exhibited (РІ. XI, figs. 4, 5). This bed can be traced
for about three miles along the edge of the hills.

А band of sphzrulitic rhyolite, in which the sphzrulites are some-
times as large as hazel nuts, is exposed ina ridge running west from
the hill with a survey mark about three miles south-west of Nagona
and can be traced for some distance along the side of the ridge between
two flows of the porphyritic rhyolite. A beautiful perlitic structure
is also developed in portions of the rock (Pl. X, fig. 6); and the same
structure occurs in a flow forming a ridge running south from the
village of Madli, about two miles to the north of Nagona.

About eight miles to the south-west of Nagona another group of
isolated hills occurs extending from the village of Tesingri (Tringri of
map) in a westerly direction for about ro miles to near Patodi. Those
at Tesingri consist of compact dark coloured rhyolites, with well devel-
oped flow-structure and columnar jointing, with a general dip at low

(70) ))

50 LA TOUCHE: GEOLOGY OF WESTERN КАЈРОТАМА,

angles to the south or south-west. These rocks are very fresh looking and
seem to be scarcely, if at all altered, the crystals of orthoclase which
they contain having remarkably well defined outlines.

Further to the west in the neighbourhood of Thob, the prevailing
rock is of the common strongly porphyritic type of rhyolite, with dark
grey and red colours. Seen from the north-west side in profile the
large hill (837 feet) appears to be built up of successive flows dipping
to the south-west at various angles up to 45°, each flow being marked
by columnar jointing. Some breccias and fluidal rhyolites are exposed
in the low ground about three quarters of a mile to the north of the
village, apparently dipping beneath the porphyritic rocks.

In the group of hills between Thob and Patodi, still further west, a
regularly stratified series of beds is exposed in a scarp facing north-east,
the beds dipping to the south-west. Red, slightly porphyritic rhyolite
is exposed at the base; above this comes a band of an almost black
rock, crowded with quartz grains and weathering with a shaly struc-
ture, probably an ash bed. Then there is another band of the red
porphyritic rhyolite, and above this a light greenish tuff, with a sandy
texture. and somewhat shaly. With this are associated some more
coarsely fragmental beds studded on the surface with small nodules
resembling lapilli. Above this there is a band of a dark grey amygda-
loid rock which looks like a contemporaneous flow of basic rock, and
is greatly decomposed. Finally, forming the crest of the ridge, is а
thick flow of compact blue rhyolite, with well marked flow-structure,
and containing fresh looking crystals of felspar. The rock is tra-
versed by a system of fine black veins, probably ccloured with iron
oxide, and roughly following the lines of flow. This series of beds is
about 150 feet in thickness and can be traced for a considerable
distance along the scarp. The main mass of the hills to the south-
west of the scarp is composed cf a thick flow of dark grey and red
porphyritic rhyolite, like that forming the hills near Thob, witha
roughly columnar ‘structure. This flow forms a dip slope gradually
descending to the level of the plain on the south-west.

( 50 )

DETAILED DESCRIPTIONS OF ROCKS. 51

Considering the chain of hills, extending from Baorli to Thob, as
a whole, it is worthy of notice that, speaking generally, the rocks to
the north-east of Nagona dip towards the north-east while those to
the south-west are inclined in the opposite direction. Moreover, we
have seen that about the centre of the chain, in the large block of hills
surrounding Nagona, there is some evidence of the presence of one
ofthe vents through which the lavas were poured out. It seems at
least possible therefore that this chain of hills represents the remnants
of an ancient volcanic cone. The inclination of the lava flows on
either side of the central area, and the form of the scarps, which points
toalarge amount of denudation having taken place, is not inconsist-
ent with the supposition of the former existence of such а cone; but
the enormous extent to which the surrounding rocks are covered up
by sand, leaving only the merest fragments of what must have been
thick flows of lava, extending overlarge areas, now visible, renders
it impossible to say with certainty whether the lavas were erupted
from a single vent, forming a cone of the Vesuvian type, from a number
of fissures, or from smaller vents of the Puy type scattered over the
surface of the country.

Beyond the southern end ofthe chain ofhills just described, no
rocks occur in the plain until the river Luni is reached at Jasol, about
20 miles to the south-west of Thob. Here on the south bank of the
river are one or two isolated hills of rhyolite, and here the first
instance occurs of rocks of a different age being associated with the
rhyolites. On the southern side of the large hill close to Jasol, which
consists ofa dark purplish porphyritic rhyolite, two broad vertical
dykes of basic rock (olivine dolerite) are intruded into the lavas. The
dykes are 50 and 30 feet broad respectively, parallel to each other and
striking W. 30°N. Branches are thrown off into the surrounding
rocks, and at one point a dyke about 15 feet broad connects the two,
running diagonally from one to the other. The material of the dykes
is dark green in colour, consisting mainly of plagioclase felspar, ser-
pentinised olivine and hornblende. It decomposes much more rapidly

CIS)

52 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.,

than the rhyolites, and is usually very rotten in texture so that it is
difficult to procure a good hand-specimen. Owing to this difference
in weathering the rhyolites generally stand up on either side of the
dykes in the form of vertical walls, and the eye can easily follow the

course of the dykes along the hill side.
About four miles to the south-west of Jasol is a very large mass

of hills, extending for about seven miles from east to west and rising at
its highest point to an altitude of 1,354 feet above the sea. The
village of Nagar is situated at the base ofthe range on the north
side, at about its centre. The whole of this range is composed of the
Malani rhyolites, in great variety, interbedded in places with breccias
and tuffs, and traversed by numerous dykes of dolerite.

Towards the eastern end of the range the rhyolite is of the
common dark grey or reddish brown porphyritic variety, but towards
the western end, and in the detached ridge to the south-west, the
prevalent rock isa dark green highly porphyritic rhyolite with very
conspicuous flow-structure. Where the lava sheets are not horizontal
they are inclined to the south or south-west at various angles up to
about 309. Some brecciated beds occur on the crest of the range a
little to the south-east of the survey mark near its western end,
associated with tuffs. "These beds are also exposed on a low pass close
to the western end of the range, where they are brought down by the
south-westerly dip. The most conspicuous is a band of light yellow
colour containing scattered angular fragments of a dark brown
rhyolite. A band of breccia beneath this is dark coloured, containing
in places large blocks of rhyolite up toa foot in diameter. These
breccias underlie the dark green porphyritic rhyolites at the western
end of the range.

Breccias are also exposed at the base of the range, about a mile
east of Nagar. The matrix of these includes small fragments of rhyo-
lite as well as large blocks up to three feet in diameter. They appear
to have undergone some denudation before being covered up by the

522)

DETAILED DESCRIPTIONS OF ROCKS. 53

overlying flow of rhyolite, as they occur in patches like heaps or
mounds surrounded by the lava. They may possibly be the remnants
of an ancient neck filled with agglomerate. The rhyolite immediately
surrounding them has an altered appearance, yellow and earthy look-
ing, perhaps due to the passage of heated vapours through the body
of the rock.

The rocks comprising the range are traversed by numerous dykes
of basic rock, of a dark green colour, consisting principally of a plagio-
clase felspar with a good deal of augite and olivine. These dykes
run along the joint planes ofthe rhyolites, the most usual direction
being due north and south, another system cutting these at right
angles. Generally their course is well marked by a depression in the
surface, since the material of which they are composed weathers more
rapidly than the rhyolites. A large chasm formed by the weathering
out of one of these dykes is seen in the hillside immediately to the
south of Nagar village (Pl. V, fig. 1) ; this dyke is 18 feet wide. About
a mile and a half to the east of Nagar is a narrow pass through the
range, the bottom of which is occupied by a broad dyke, 155 feet
wide, to the weathering out of which the formation of the pass is due.
Another pass close to the east end of the range has been formed in
а similar manner. Again, near the western end of the range, оп the
northern slope beneath the survey mark, are two broad dykes crossing
each other at right angles, and bounded by lofty vertical walls of
rhyolite. The north-south dyke is 45 feet and the other 30 feet wide.
Some of the dykes split up into a number of narrow parallel branches,
running in among the rhyolites; one of these, on the hillside a
little to the east of Nagar, is altogether about go feet wide, and
includes about a dozen alternations of dolerite and rhyolite. The latter
lias lost its colour, but does not appear to be otherwise altered.

About eight miles to the south-east of Jodhpur, near the village of
Rassida, and again at Salawas, 12 miles south of -the city, a coarse
granite is exposed forming tosses rising abruptly from the surrounding

(53)

54 LA TOUCHE: GEOLOGY OF WESTERN RAJFUTANA.

sand. It is composed of quartz, pink felspar, mica, hornblende and
a bright greenish yellow mineral probably epidote; it weathers into
rounded exfoliating masses and shows no traces of foliation, though
it is traversed by roughly parallel joints which give ita certain
appearance of being bedded Included in it are numerous rounded
patches of a darker coloured rock, measuring up to 6 inches in
diameter, some of which appear to be fragments of schist. They
are always more fine grained than the surrounding granite, but some
of them contain the same ingredients, with a larger proportion of
small crystals of mica or hornblende, which give them their darker
colour, and these may be concretionary in origin, being merely the
result of an abnormal arrangement of the constituents of the granite.
Exactly similar patches are described by Mr. J. Arthur Phillips, as
occurring in many of the granites of the United Kingdom, ina paper
"on Concretionary Patches and Fragments of other Rocks con-
tained in Granite,"! where the author comes to the conclusion that
some are of concretionary origin, while others, generally schistose in
character, are foreign fragments derived from the rocks through
which the granite has forced its way. | :

Seven miles to the east of Salawas, on the right Ee of the Luni
river near the village of Rajpura, a large spread of Malani lavas
occurs, forming a low rise extending for some two miles along the
river bank. All the rocks exposed are lavas of different varieties,
some strongly porphyritic, and others exhibiting good flow-structure.
Mr. Hacket says that he found some very much decomposed olive
green schists in the bed of the Luni almost in contact with the lavas,
but that no junction between the two was exposed. These schists
were covered by the sand of the river at the time of my visit, and I
could not find them.

Two small hills, both composed of rhyolites, occur isolated in the
plain a few miles to the south and south-west of Salawas. The

2 Quart. Journ. Geol. Soc, Vol. XXXVI, p. 1.
( 54 )

DETAILED DESCRIPTIONS OF ROCKS. 55

larger of these, near the village of Phinch, rising to an altitude
of 1,001 feet, corsists of red or purple rhyolite without porphyritic
crystals, dipping to the south-east at between 25 and 30 degrees.
In places the rock has an ashy look and contains imbedded fragments
cf rhyolite.

The large group of hills near the railway station of Khairla, about
11 miles north-west of Pali, is mainly composed of a coarse granite
similar to that above described at Salawas, and like it containing
rounded patches upto a foot in diameter of a darker coloured more fine
grained rock, some of which may be included fragments. On three sides
of the granite schists and slates are exposed, but in no case are they
found actually in contact with it. They are usually vertical and much
contorted, with a somewhat variable strike, the prevailing direction
being N. E. to S. W. The slaty beds are badly exposed in the
shallow watercourses on the western side of the large hills close
to the railway station, and may be traced across their strike over the
low ground to the north-west to within a few hundred yards of a low
ridge of Malani rhyolites, the flows in which dip due west at- from
45 to 50 degrees. These probably rest unconformably on the edges
of the slates, but the actual junction is notseen. The rhyolite here
isa dark purplish variety, sometimes porphyritic and with well devel-
oped flow-structure, the lines of flow coinciding with the dip. The
granite hills rise quite abruptly from the plains, and there is little
doubt that they are intrusive bosses, although the contact with the
surrounding schists and slates is concealed. à

At Samdari on the north bank of the Luni, 23 miles above Jasol,
there is an isolated hill of rhyolite, reddish yellow in colour, with
flesh coloured porphyritic crystals of felspar and the usual quartz grains.
One or two small hills of a similar rhyolite occur lower down the river,
and at Mongla, six miles from Samdari, there is one consisting of a
dark green porphyritic rhyolite similar to that in the western end of
the Nagar range.

(1155240)

56 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

Proceeding southwards from this point one is struck on approach-
ing the hills near Meli, about three miles from the river, with their
rounded aspect as compared with the usual rugged character of the hills
composed of rhyolite, and on reaching the hills one finds that this
difference in appearance is due to a radical change in the composition
and texture of the rocks. The ridge which runs in a north-westerly
direction for about six miles from the village of Deora is in fact mainly
composed of a coarse granite, the microscopic constituents of which
are quartz, felspar and hornblende лла zo mica. This rock weathers
into rounded, exfoliating masses and frequently assumes somewhat
fantastic forms. Тһе fragments that fall from the sides of the hills
formed of it are quickly broken down into a coarse sand, and the
bare sheets of granite rise abruptly from the plain, with no covering of
talus, such as is found on the slopes of the hills of rhyolite.

The relations of the granite with the rhyolite are well seen in the
ridge immediately north-west of Meli, on its northern side. The
rhyolite occurs in patches at the base and here and there on the flanks
of the hill, sometimes running up to the crest, and generally dipping
to the north at angles corresponding with the slope of the surface of
the granite, as though the latter had been forced up from beneath as a
dome or boss, and thrust aside the sheets of lava above. Тһе boundary
between the two is always perfectly abrupt, and the granite is evi-
dently intrusive. It sends off narrow veins into the rhyolite ramifying in
all directions through the latter. The granite of the veins is frequently
a coarse pegmatite, containing well shaped crystals of hornblende an
inch or more in length. Near the junction the joint planes of the
rhyolites are often covered with a thin glaze of granite, the latter
having evidently been-forced in among the rhyolites under great pres-
sure and in a very fluid state. The rhyolites here do not appear to
have been altered by the intrusion, but in other localities, to be noted
later on, signs of alteration are not wanting. + Along the southern side
of the ridge the rhyolites are not exposed, probably having been

( 56 )

DETAILED DESCRIPTIONS OF ROCKS, 57/

denuded and covered up with sand. To the west the granite ridge
slopes very gradually down to the plain, the end of it being rounded
off on either side like the crown of a dome.

. 3. Quarter Sheet 20 S. E.

The ridge just described forms the northern edge of a very large
group of hills, about the centre of which is situated the town of Siwana
at the foot of a steeply scarped hill on which is built an ancient fort.
From about a mile south of the westerly termination of the granite
ridge, two others run more or less continuously for about 10 miles in a
west-south-west direction to near the village of Thapan. Both of these
are steeply scarped to the north, but present sloping surfaces, corres-
ponding to the inclination of the rhyolite flows composing them, to the
south.

At the base of the more northerly of the two ridges, near the east
end, a dark grey vesicular rock, very trap-like in appearance, is
exposed, and seems to be intrusive along the strike of the rhyolites.
The relations of this rock with the lavas are, however, somewhat
obscure. In one place, about a mile from the end of the ridge, it is
certainly intrusive, being thrust up vertically through the rhyolites
which stand up on either side of it like a wall, and a little further to
the west it runs in among them in narrow bands and appears to alter
them. Further west again the same rock seems to be interbedded
with the rhyolites, and is associated with dark grey ashy looking beds.

Towards the east end of the ridge the rhyolites forming the
upper part of it are a dark brown variety with large crystals of red
felspar often in strings drawn out in the direction of flow, dipping to
south-south-west at about 20°. Further west a thick band of rhyolite
with well developed flow-structure, frequently vesicular in its upper part,
crops out in places beneath the porphyritic variety. In one place a
narrow dyke of rhyolite in which the lines of flow are vertical runs
from cast to west through these rocks. The upper lava flows dip to

(7757!)

58 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA. |

the south or south south west and form a bare dip slope on the
southern side of the ridge inclined at an angle of about 20?. Nearer the
western end the dip curves round to south-south-east at about the same
angle, and the rhyolites both above and below the trappoid band are
of the ordinary grey or reddish brown porphyritic variety.

A dyke or boss of dolerite rises through the rhyolites on a low pass-
to the east of the road through the ridge from Siwana to Pachpadra.
It is 70 feet wide and runs from north-west to south-east, but is
only exposed for a short distance on either side of the pass. The
materialis very much decomposed ; at the edges it has caught up large
fragments of the rhyolite, which weather out in rounded троа
masses, each surrounded by concentric shells of dolerite.

The southern ridge, when looked at from a distance, appears at first
sight to be a repetition of that to the north, but on closer inspection
the rocks composing it are found to be quite distinct. The detached
hills at the east end are all porphyritic rhyolite of the ordinary type,
with some vesicular bands dipping to the south-south-west at 30 to 35
degrees. The upper portion of the main ridge is of similar rhyolite, but
at the base on the northern side, which is steeply ‘scarped, some very
different beds are exposed. These are sandy and gravelly, containing
rolled pebbles of rhyolite, and form a band from 20 to зо feet thick
with sheets of rhyolite above and below. Further to the west, at a
pass due north of the village of Kuip, and on the west side of the peak
marked 1,319 feet, these beds are better seen, and are altogether
about 100 feet thick, consisting of pebble beds interstratified with
breccias and felsitic tuffs. In the uppermost pebble bed rolled frag-
ments of other crystalline rocks, gneiss and quartzite, as well as the
rhyolites, are found. One of the rhyolite pebbles found was a variety
containing large red crystals of felspar similar to that in the northern
ridge. At the pass these beds are broken through by a dyke of
strongly porphyritic rhyolite, 60 feet wide, running directly across the
ridge; near the contact with this dyke the pebble beds are highly in-
durated. The pebble beds and tuffs extend along the base of the

(125329

DETAILED DESCRIPTIONS OF ROCKS, 59

ridge to the west of the pass through which the road to Pachpadra
runs, but in that direction they are_more or less concealed by sand-
hills. The rock below them .crops out about a mile beyond the pass
and is a red porphyritic rhyolite. Above the pebble beds come thick
sheets of a very dark grey variety of rhyolite only slightly porphyritic.
The pebble beds and the sheets of rhyolite above and below are quite
conformable to each other, dipping to south-south-east at about 25°.
The southern side of the ridge is a steep dip slope formed of bare
sheets of rhyolite.

In the hill rising to 1,634 feet, about three miles west-south-west
of the village of Kuip, some greenish ash beds, about 30 feet thick, are
exposed near the base of the spur on the north-east side, dipping to
the south at about 20°. These are pierced by a dyke or rather boss
of red rhyolite forming a low dome surrounded on all sides by the ash
beds. The latter are succeeded above by thick flows of vesicular
rhyolite, and these by successive sheets of the ordinary variety of
porphyritic rhyolite, forming the mass of the hill, and steeply scarped
on all sides, rising above each other like the steps of a staircase
(РІ. III, fig. 1). Towards the south side of the hill these flows become
nearly horizontal. |

The large scarped hill rising to 1,601 feet to the south of that last
described, and about two miles north of Garah, is also composed
entirely of rhyolite. The main mass of the hill at its western end
consists at the base of brick red rhyolite full of porphyritic crystals of
red felspar, extending for about 300 feet up the scarp. This is
succeeded by thick flows of red rhyolite without porphyritic crystals.
The junction between the two is quite abrupt, and they are evidently
distinct flows. Towards the east the rocks are inclined to east-south-
east and the non-porphyritic rhyolite is brought down to the level
of the plains. Here a well developed flow-structure is seen in some
portions of the rock.

The small detached group of hills between this and the hill at
Siwana also consists of the brick red non-porphyritic rhyolite, with a

(7-50) =)

60 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA,

small quantity of porphyritic rock with red felspar crystals exposed at
the base.

The lower part of the scarped hill on which the fort at Siwana is
built is composed of tuffs of various colours, pink, buff, purple and
green, with thin bands of rhyolite interbedded among them. At the
base they are conglomeratic, containing rolled pebbles of rhyolite, and
rounded blocks a foot or more in diameter. These beds are about
40 feet thick on the southern side of the hill, resting on red rhyolites
without porphyritic crystals, and are overlaid by a thick flow of dark
brown rhyolite, with a roughly columnar structure, on which the fort
is built. The tuff beds extend all round the hill at the foot of
the scarp below the fort, and on the northside are from 80 to.
100 feet thick, dipping in slightly towards the hill on all sides. On
the west side they are either banked up or faulted against the rhyolites
of which the western portion of the hill is composed. The tuffs have
every appearance of having been laid down under water.

Beneath the high peak at the western end of the hill a bed of
conglomerate, consisting entirely of well rounded pebbles of the rhyo-
lites, is intercalated between the flows. This band is from 20 to 30 feet
thick. It does not appear to correspond with the conglomerate band
below the fort, for the tuff beds are wanting. Some sandy looking ash
beds are exposed immediately above the conglomerate band on the
southern face of the peak, and are hollowed out into a deep gallery
running horizontally along the hillside beneath the scarp. The соп-
olomerate band dies out before reaching the western end of the hill, and
Y replaced by ash beds and thin bedded rhyolites. The rhyolites above -
and below are of the red or reddish brown non-porphyritic variety.
They dip, with the conglomerates, at 20° to the north.

The structure of the large hill, 1,790 feet high, to the north-east of
Siwana, is very similar to that of the hill already described to the
south-west of Kuip. The beds are inclined to the south, dipping on

the north side at 27 or 30 degrees, and becoming more horizontal

( бо )

DETAILED DESCRIPTIONS OF ROCKS. 61

towards the south. The lowest beds exposed on the north side are
brick red non-porphyritic rhyolites, similar to those in the hill west of
Siwana. These are succeeded by reddish ochrey porphyritic rhyo-
lites, which form a spur, steeply scarped on the north face, running out
towards the west. In the depression between this spur and the main
mass of the hill is a thick band of ash beds, which runs diagonally up
the slope to the north of the rhyolite cliffs forming the crest of the hill,
and down to the plains on the east side. On this side there appears
to be two bands of ash beds separated by a thick flow of rhyolite, but
this apparent doubling of the band may be due to faulting or to slip-
ping of the beds forming the scarp. The total thickness of the ash
beds is about 250 feet. They are succeeded by brownish red rhyolites
which are very slightly porphyritic, forming the crest and the whole
of the southern portion of the hill. |

In the plain to the east and north-east of the hill last described are
several small knolls all of rhyolite, of the ordinary type. At the north-
ern edge of one of these, close to the village of Bijli, are two small
outcrops of the coarse hornblendic granite, one of which is in contact
-with the rhyolites, and throws off veins into them. The same granite
forms a large mass of hills to the east between Balu and Phulan, but
although it is surrounded by exposures of rhyolite, one, immediately
north of Balu, of considerable area, the two rocks are nowhere seen in
contact. On the south side the rhyolites dip steadily away from the
granite at an angle of 30? to south-west, while in the small exposure
to the east, between the granite hill and the village of Raki, the dip
is from 30° to 35? to the east. Неге again the granite seems to have
been forced as a dome shaped mass or laccolite among the rhyolites,
and to have tilted them up on either side.

To the south-west of this group of hills another area of granite is
found in the hill between Ajiana and Ludrara, and here the relations
between the granite and rhyolite are well displayed. The central
portion of the hill consists of rhyolites which dip to the north-west at

(6r)

62 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

about 30°, away from the large mass of granite forming the eastern por-
tion of the hill towards Ludrara. The granite and rhyolite are here ia
contact, the former as usual sending off numerous veins into the
latter. The rhyolites are of the ordinary porphyritic type, occasionally
containing large crystals of red felspar. Close to the granite on the
north-west side a thick band of pebble beds and breccias is inter-
stratified with the rhyolites. The contact of these beds with the
granite is concealed by sand.

Another exposure of the pebble beds occurs ina small hill rising to
927 feet, close to the village of Siner, about 10 miles to the west of
Siwana. At the base are some rhyolites with flow-structure succeeded
by strongly porphyritic rhyolite. These are exposed at the south-west
side of the hill close to the village. Upon them rests a bed of a dark
greenish rock of basic type, portions of which are amygdaloidal.
Then comes a band of conglomerate in which the pebbles are well
rolled, consisting of rhyolites of various types, some showing good flow-
structure, and a few of quartz. This band is about five feet thick and
is succeeded by a band of highly vesicular rhyolite of a dark greenish
colour, and on top of all a thick flow of rhyolite of the ordinary por-
phyritic type. All these beds dip to the north-east at an angle of
about 35°. А diagrammatic section of the hill is given in fig. 1,
Pl. IV. The pebble bed can be traced all round the western side of the
hill, and appears again in a smaller hill about a quarter of a mile away
tothe north. Here besides the pebbles of rhyolite and quartz it contains
a few, also well rolled, of a micaceous gneiss or gneissose granite.

A dyke of rather coarse grained dolerite, 30 feet wide, breaks
across the larger hill through the rhyolites and conglomerate band,
striking from south-east to north-west. On the southern side of the
hill it runs parallel to the bedding of the rhyolites and conglomerate
for a short distance, just beneath the latter, and divides into two
branches as shown in the section. It also appears on the same strike in

the smaller hill to the north.
( 62 )

DETAILED DESCRIPTIONS OF ROCKS. 63

To the north of the hill at Siner there is another large mass of
the hornblendic granite, in the range a short distance west oí the
village of Indrana. On the south-west side of the range the rhyolites
are in contact with the granite, but here the former dip directly
towards it, that is to the east-north-east at an angle of about 20° (PI.

.HI, fig. 2). The junction of the granite and rhyolite is very well snown
on the western slope of the hill beneath the survey mark (1,346 feet).
The granite abuts vertically against the rhyolite and has thrown off
numerous veins into it; in addition the granite has torn off large blocks
of the rhyolite and included them. The rhyolite, near the contact with
the granite and in the included blocks, is considerably altered; and is
full of small nests of hornblende. The granite of the veins is usually
very coarse in texture, especially towards the middle of the vein, where
the hornblende crystals are frequently from 3 to 4 inches in length.
A good instance of the manner in which the granite veins penetrate the
rhyolites is seen at the western end of a detached mass of granite to
the south of the range (Pl. IV, fig. 3). A dyke of dolerite t2 feet wide
runs through the rhyolites from north to south, a short distance from
the boundary between the granite and rhyolite and parallel to it.

The range a few miles further to the west and parallel to the In-
drana range is entirely composed of rhyolites. At the southern end
they exhibit good flow-structure and dip to the north east at about 25°.
Further north are red rhyolites only slightly porphyritic. In the midst of
these there is a well defined band of breccias about 20 feet thick, which
can be traced to near the northern end ofthe range. Here the beds
are inclined to the east at about 30°. In a small detached hill to the
east of the middle of the range a thick band of much decomposed dia-
base, apparently interbedded with the rhyolites, is exposed ; it is over-
laid by green rhyolites with porphyritic crystals of bright red felspar.

Some five or six miles to the south of Siwana isa very large mass
of hills, extending for nearly 17 miles from east to west and about 6
miles across in its broadest part; rising to an altitude of 3,199 feet
above the sea at its highest peint, or about 2,500 feet above the plain.

(25630)

64 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

This is the largest continuous mass of rock to the west of the Ara-
vallis. On the map it is named Saora, but among the natives this name
seems to be confined to the portion, including the highest point, im-
mediately south of the village of Golia, situated about midway of the
range on the north side. By far the greater part of the hill, including
all the higher portion, is composed of the coarse hernblende granite
which appears to be everywhere identical in texture except that it
is frequently traversed by broad veins of a finer grained rock, or eurite,
of the same composition as the surrounding granite. Occasionally
these veins contain large porphyritic crystals of pink felspar, and the
material then resembles the Malani rhyolites to some extent, but is
easily distinguished from the latter by its lighter colour and its less
glassy texture. The rhyolites are found in contact with the granite
on the spurs all along the northern side of the range, but except for a
very short distance near the west end, they do not occur at all on the
southern side, where the boundary between the granite and the rhy o-
lites forming the hills further south is everywhere cencealed by sand-
hills.

At the western end of the range a large area of rhyolite extends
from a narrow ravine immediately south of the small village of Jhika,
or about four miles to the west. The rhyolite in the whole of this area
is very homogeneous in texture, and almost holocrystalline in appear-
ance from the large number of felspar crystals and quartz grains
which it contains. It weathers into rounded exfoliating masses, so that
ata distance it is difficult to distinguish it from the granite. The
contact between this rock and the granite is exposed in the ravine
south of Jhika. The line of junction runs N. W., S. E., and is quite
abrupt and vertical, but it does not appear to be faulted. The bedding
of the rhyolites is either horizontal or undulating, but towards the
west they dip to the north and north-east at angles varying from 20 to
30 degrees. А detached ridge to the north consists of dark red rhyo-
lite with few porphyritic crystals, dipping to the north-east. Near the
south-east end of this ridge a band of strongly porphyritic rhyolite, with

( 64 )

DETAILED DESCRIPTIONS OF ROCKS. 65

large crystals of pink felspar, crosses it, apparently interbedded with
the less porphyritic rock ; and still further in the same direction a
band of diabase, vesicular in places, is badly exposed above the Dor:
phyritic rhyolite and is also apparently interbedded. A small patch
of granite is exposed at the base of the ridge close to this end on the
north side. The veins running into the rhyolites from this are very
coarse in texture, with crystals of hornblende up to three inches in
length.

Along the northern side of the main range the patches of rhyolite
exposed on the spurs apparently form the remains of a dome arching
over the granite, the relics of what were once continuous sheets, rising
into jagged peaks easily distinguishable at a distance from the more
rounded contours of the granite. Occasionally, however, the rhyolites
are seen to strike directly towards the granite, and it appears as
though the latter had partly invaded and remelted the rhyolites, al sorb-
ing and replacing them, and had partly forced up the sheets of rhyolite
from beneath, Large masses of the rhyolite have been broken off and
included in the granite, and sometimes the edges of these masses have
been altered, the porphyritic crystals visible in the interior of the mass
having disappeared. Veins of granite, sometimes fine and at other
times coarse grained, are nearly always to be found intrusive in the
rhyolites near the boundary (Pl. IV, fig. 4).

In a ravine about half a mile to the south of Golia a band of bree-
cias and tuffs occurs in the rhyolites close to the granite boundary
and strikes directly towards it. Here the band is not altered where it
is in contact with the granite, but further to the east, at the head of a
broad valley due east of Golia, where a similar band of breccias and
tuffs, probably the same, is again exposed, the tuffs on approaching the
granite are altered into a porcellanous rock with a conchoidal fracture.
Some of the fragments in the breccia beds are water worn pebbles.

Less than two miles to the south of the Saora range another large
mass of hills runs parallel to it, extending for about 14 n iles from east
to west and about 5 miles from north to south, and гіш to an altitude

(Ко

66 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

of between two and three thousand feet above the sea. This is en-
tirely cut off from the Saora range by a broad belt of level ground
covered with sandhills. The rock composing it is mainly a strongly
porphyritic rhyolite exactly similar to that forming the large area at the
western end of the Saora range, and like it, weathering into rounded
masses closely resembling the granite. Some less porphyritic black
and red rhyolites, the former exhibiting flow-structure, are exposed at
the east end of the range, underlying the porphyritic rhyolites, and with
these are associated thin beds of breccia. The inclination of the flows
is generally northerly, and the hills present precipitously scarped faces
to the south. Near the top of a pass immediately to the south of Dhira
is a band of a peculiar reddish coloured rhyolite containing large sphe-
rical concretions or spharulites an inch or more in diameter. The
same rock is found at the base of the range on the southern side
near Gogoji-ka- Than and extends for some distance to the west. Here
also some breccias are interstratified with the rhyolites.

Granite was found in only two places among the rhyolites of this
range, and in each case the outcrop is very small. One ofthese isat the -
base of a spur a mile or so to the south-east of the village of Kundal,
and the other in a large valley. to the south-west of Selo, about two
miles south-south-east of the Kundal outcrops. This granite is more fine
grained than the hornblende granite of the Saora range and differs from
it in containing mica. A similar granite but more coarse in texture
forms a detached hill about two miles west of the main range, close to the
village of Kanki, where it is also in contact with a small patch of rhyo-
lite. This micaceous granite is similar to that of which the large hill
at Jalor, several miles to the south-east, as well as many of the smaller
hills in that neighbourhood, is composed.

A few miles to the north of the town of Chanod a range of hills runs
ina north east to south-west direction for about 25 miles, broken
through in the centre by the Sukri river, which runs north-west from the
Aravallis to join the Luni near Samdari. The range attains its greatest

elevation almestsdue west of Chanod where it rises to an altitude of 2,172
(бб)

DETAILED DESCRIPTIONS OF ROCKS. 67

feet above the sea, or about 1,500 feet above the plain. The elevation of
the portion of the range north of the Sukri is much less. The greater
part of it is built up of flows of Malani rhyolites of various types with
occasional bands of tuff and breccia. The prevailing type in the north-
ern portion of the range is a compact rhyolite with well developed
flow-structure, sometimes containing vesicles drawn out in the direc-
tion of flow. The usual dip is westerly or south of west at angles varye
ing between 25 and 30 degrees. Some angular fragments of a liglit
greenish hornstone occur in places imbedded in these rocks; they are
probably fragments ot the underlying slates that have been caught up
by the ascending lava and highly altered.

The only instance yet discovered of a visible junction between the
Malani lavas and the underlying Aravalli rocks occurs among these hills
in a valley lying about two and a half miles to the south-east of the
village of Miniari and 7 miles north of Chanod. The section exposed
here has already been described in Chapter UL)

A peculiar band of nodular rhyolite occurs among these hills in the
detached portion lying to the north of Miniari. The rock is crowded
with nodular concretions up to six inches or so in diameter, some of
which are almost perfect imitations of fossil shells. The matrix in

| which they occur is a compact flinty rock with a reddish colour. , Some
of the nodules contain cavities filled with crystalline quartz and a little
calcite. This is the only instance I have met with in which carbon-
ate of lime is associated with the lavas, except the crust of recent
origin, which is often formed on the surface of fragments of the lava
imbedded in the sandhills. s {

A nodular bed also occurs in the isolated hill at Bhaori, about 4 miles
to the north-west of Miniari, where it is associated with nearly white
slaggy lavas in which scattered blocks of rhyolite are imbedded. A
small patch of a friable rusty looking rock with fragments of rhyolite,
some of which appear to have been rolled, also occurs among the white

Supra, p. 19.
O70)

68 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

lavas. The dip of the whole series is to north-north-west at various
angles up to 45°.

About the centre of the range, where the Sukri river breaks
through it, a large area of granite is exposed in the bed of the river
and its tributaries to the south. This granite is rather coarse grained,
containing pink felspar and mica, and is therefore of the Jalor type. It
does not rise above the general level of the country as in the case of
all the other bosses met with, but is exposed only in the bed and banks
of the streams. It is in contact with the rhyolites at one point only,
in the bed of the Sukri about a mile south of the village of Darri, and
is there clearly intrusive, sending off veins into the lavas and includ-
ing blocks of them. A small patch of Aravalli schists occurs a little
higher up the same river, near the village of Bhaonagar, but is not
seen in contact with either the granite or the rhyolites. The schists
have the usual north-east south-west strike, and are nearly vertical.

The southern portion of the range, to the south of the Sukri, con-
sists mainly of a compact black rhyolite with porphyritic crystals of
white felspar. It often exhibits beautiful flow-structure. Bands of
breccia and agglomerate also occur, and some of the flows are amyg-
daloidal. The dips are very varied and it is sometimes impossible to
make out any bedding in the rock. It looks as though it had welled
out from a fissure parallel to the length of the range; atthe base of
the hill, on the east side, about a mile south of the village of Malgarh,
the lines of flow are vertical, as though the lava had been subjected to
lateral pressure while it was being poured out.

'The southern slope of the detached hill north of Chondrai, which
appears to be on the continuation of this range, consists of the same
black porphyritic rhyolite with a southerly dip. Beneath this, forming
the whole of the lower portion of the slope on the north and east
sides, a boss of coarse granite containing mica forms a rounded dome
supporting the.rhyolites. Along the line of contact it is clearly intru-

sive in the latter, throwing off narrow veins into them, and in one place
( 68 )

DETAILED DESCRIPTIONS OF ROCKS. 69

à sill occurs running parallel with the bedding of the flows a short
distance above the junction with the granite. Near the boundary it
sometimes includes blocks torn from the rhyolites, and I found one
fragment of a dark coloured schistose rock imbedded in it, probably
derived from the underlying schists. Closeto the plane of contact the
granite sometimes has a foliated appearance, and this is very con-
spicuous in some of the veins which traverse the rhyolites.

The large mass of hills at Kaonla village, 7 miles south-west of
Chanod, is entirely composed of a similar granite, traversed by thick
veins of a fine grained eurite. These hills furnish a good example of
the characteristic dome shaped weathering of the granite bosses
(Pls. VI, VII).

The rhyolite of the main range near its southern end is traversed
by several dykes of diabase which strike across the hills in а north-
westerly direction. They are generally found in depressions on the
crest of the range, the diabase weathering more rapidly than the
rhyolite. A small dyke of the same kind occurs at the base of the
large hill at Kaonla cutting through the granite, and at the same time
— piercing a vein of eurite which also traverses the granite.

In the isolated hill at Pati, 18 miles north-west of Chanod, an in-
teresting section is exposed. The lower portion of the hill on the
southern side is composed of sandy pebbly beds, purple and greenish
yellow in colour. These extend up to the foot of a precipitous
scarp of rhyolites which form the whole of the crest and northern
slope of the hill, and rest conformably upon the sandy beds, the whole
dipping to the north-west at about до degrees. In places the sandy
beds show distinct current or false bedding and have evidently been
laid down under water. At the top of these beds, at the foot of the
scarps, is a band containing rolled pebbles of rhyolite up to six inches
in diameter. The upper part ofthis band is highly indurated, appa-
rently by the heat from the overlying flow of lava. About 200 feet

of the sandy beds are exposed, but their base is concealed by talus,
( 69 )

70 LA TOUCHE: GEOLOGY OF WESIERN RAJPUTANA.

and to the south-east they are covered by alluvium ; one or two small
patches of the rhyolite which probably underlies them occur in this
direction about two and a half miles away on the banks of the Sukri.
A few miles to the west of Pati а considerable range of hills runs
due north and south for about 11 miles, rising to an altitude of 2,112
feet above the sea at its highest point close to the town of Bhadrajun,
which lies in a narrow ravine on the eastern side of the range near its
southern end. The whole of this range consists of various types of
rhyolite. To the north of the village of Goendla, about the middle of
the range, the prevailing rock is a strongly porphyritic dark coloured
rhyolite, with white or red crystals of felspar, with a general westerly
dip. At the base on the east side some nodular and spherulitic
flows are exposed in places, and near the village of Bakhal, at the
north end of the range, is a highly concretionary bed, the concretions
in which reach a diameter of at least two feet (Pl. V, fig. 2). At
Goendla itself some ashy beds containing small lapilli of rhyolite as well
as rounded blocks up to 10 inches in diameter, associated with fine
grained reddish tuff, are exposed in a watercourse at the foot of the
hills. Above these come some strongly porphyritic rhyolite, and then
thick flows of compact dark grey rhyolite, forming precipitous scarps
facing east. These are succeeded by the porphyritic rhyolite continued
southwards from the northern end of the range, the whole of the
slopes on the western side being formed of this rock. To the south
the compact rhyolites rise into the high craggy hills above the town
of Bhadrajun and form the greater portion of the southern end of the
range. Some of the flows exhibit very well developed flow-structure.
Brecciated beds occur on. the southern side of a pass through the
range south of Bhadrajun, and are intercalated with the rhyolites.
The whole of the rocks dip at various angles in a westerly direction.
About four miles to the west of this range another chain of small
hills runs parallel to it for about six miles from north to south. These

hills all consist of the coarse micaceous granite, but are quite isolated,
(non

DETAILED DESCRIPTIONS CF ROCKS, 71

and the granite is not seen anywhere in contact with the rhyolites.
A number of small isolated hills of a similar granite occur scattered
over the plain to the sou h-west in the direction of Jalor. In one of
these, near the village of Sakarna, 5 miles east of Jalor, a large
mass of rhyolite is seen running through the granite like a dyke, and
at first sight apparently intrusive in it. It is, however, traversed by
veins from the granite, and is evidently a mass of rhyolite that has
been split off and imbedded in the granite. The rhyolite has ap-
parently been partially remelted at the edges, for a fluidal structure
following the irregularities of the boundary has been developed in it
and it has lost its dark colour for about half an inch from the junction.

The granite of these hills is sometimes traversed by dykes of diabase
running from westeaorth west to east-south-east. One of these, at the
southern end of the hill at Godhan, near Sakarna, is about 50 feet wide.

The large hill on which the fort at Jalor is built, and the greater
portion of the hill called Roza, to the west of the fort, is formed of
the same granite. The western part of Roza hill, however, consists
of Malani rhyolites, which rest upon the granite and dip away from it.
The bcundary between the two is everywhere concealed by talus and
scrub jungle, but it appears to run nearly north and south along the
ridge, rising to 2,118 feet on the west side of Roza hill. The rhyolite
also appears in the two isolated hills west of Tarwa, about seven miles
west of Jalor, and in the more northerly of the two is in contact with
granite. Here the latter is clearly intrusive, sending off large dyke-like
masses among the rhyolites. A small hill of rhyolite also occurs to the
north, on the right bank of the Joai river, near the village of Saparo. It
seems likely that the rhyolites underlie most of the plain, and may
extend to the north-west to the large mountains south of Siwana, and
that the granite forms bosses protruded through them. Except where
these isolated hills appear above the plain, however, the ground is
entirely covered with blown sand.

In the neighbourhood of Jalor the granite is traversed by several

(ЛШ)

72 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

large dykes of olivine dolerite. One of these, which is quite 200 feet
wide, may be traced at intervals along the base of the hill to the south
of Jalor town. The dolerite is greatly decomposed, and weathers
more easily than the granite, so that the latter stands up like a wall
on either side of it. Several dykes also run through the granite of
the hill itself, their course being marked by deep chasms weathered
out. Another very large one occurs in the pass between Jalor fort
and Roza hill. The dolerite in this is in a better state of preservation,
and in the centre of the dyke is rather coarse grained. At the northern
end of the pass this dyke splits up into a number of smaller parallel
dykes, and in contact with the granite the dyke rock becomes very
fine grained and has a vertical platy structure parallel to the walls.
All the dykes run in a north-north-west, south. south-east direction.
The large hills to the south and south-east of Jalor were surveyed
and mapped by Mr. Hacket. They lie for the most part in the State
of Sirohi and are not included in the area which I surveyed. To the
north of Erinpura, however, there is a considerable mass of hills lying
in Jodhpur territory, and as the conclusions I came to regarding the
rocks exposed in them differ somewhat from those of Mr. Hacket, it
is perhaps worth while to give such information as I can about them.
The relations of the rocks composing these hills are well seen in
the detached hill at Sanderao, a village about 13 miles north-east of
Erinpura, on the old road from Ahmedabad to Ajmere. The main
mass of the hill consists of quartzite with schistose bands, nearly
vertical and striking in a general north-east, south-west direction. On
the east side of the hill a large mass of gneissose granite is exposed,
which was evidently originally intrusive, since it sends off veins into
the quartzites. The intrusion must have taken place prior to the dis-
turbance and folding of the quartzites, for the granite has become
foliated, and the fragments of schist included in it, which are very
numerous in places near the boundary, have been rolled out into len-
ticular patches. The granite of some of the veins is also foliated,
especially where they run parallel to the bedding of the quartzites.

(527277)

DETAILED DESCRIPTIONS OF ROCKS. 73

Several dykes of dolerite run through the rocks, traversing both the
quartzites and the granite veins. The largest of these occurs in a
ravine at the north-east corner of the village; the rock is coarse
grained and a good deal decomposed, forming a dyke about 12 feet
wide striking north and south. A few yards up the ravine it sends off
a branch to the north-west. Several granite veins occur in the same
ravine, cutting across the strike of the quartzites and in turn cut
through by the dolerite.

The whole of the northern portion of the large mass of hills
between Sanderao and Erinpura, extending from near Khadalo station
on the Rajputana-Malwa railway to the Joai river, about five miles
below Erinpura, consist of dark со!ош ed Aravalli schists with bands
of quartzite. The strike varies between north-north-east, south-south-
west, and east-north-east, west-south-west, but is generally in the latter
direction. Over the low ground to the south of these hills an exceed-
ingly coarse granite crops out, forming low hummocks scattered over
the plain, and occasionally rising to a greater height, as in the hill at
Khidara and in the long ridge to the south of this village running
parallel to the road. This rock is not often seen in contact with the
schists, but where it is visible the junction is very irregular, and the
granite sends off veins among the schists and includes fragments of
them. As at Sanderao the granite near the boundary is generally
strongly foliated, and the veins which traverse the schists are some-
times contorted, showing that the granite must have been injected
before the folding of the schists took place (Pl. IV, fig. 2). This
granite is therefore far older than the granite associated with the Malani
rhyolites to the north and west. It also differs from that granite lithologi-
cally, being exceedingly coarse grained and containing crystals of
whitish felspar often three inches or more in length. Among these hills
a few dykes were met with, generally running in a west-north-west,
east-south-east direction or at right angles to the strike of the schists,
and traversing both these and the coarse granite.

lhis granite also forms the large hills to the east of Erinpura Road

(27731)

74 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

D

Station, where the usual “ granitic” mode of weathering is well dis-
played (Pl. Vlil), and extends for many miles to the north along the

base of the Aravallis, in Godwar.

4. Barmer Area.
38 53,
39 54

The quarter sheet of the Atlas of India that would include the
Barmer desert has not yet been published, but very nearly the whole

Rajputana Survey, r inch=2 miles, sheet

of the solid rock that appears above the sand in this area is mapped
in the half inch sheet of the Rajputana Survey cited above, and I shall
use that in describing the geology of the district.

On the eastern side of the desert, after leaving the rocky hills
south of Jasol, solid rock is first met with on the right bank of the
Luni, near the village of Dandali. Неге there are two or three
conical hills, the highest rising to 1,038 feet above the sea, consisting
of a coarse grained hornblendic granite without mica. These hills are
quite isolated, but a short distance to the south there are afew low
hills composed of Malani rhyolite, a dark grey variety with numerous
white crystals of felspar and quartz grains. The granite is traversed
by narrow dykes of a fine grained dark grey eurite running north and
south parallel to each other. This rock is very similar to the rhyolites
in appearance, but it is impossible to say whether the dykes are con-
nected with the flows.

About seven miles to the west of these hills there are three
outliers of the Barmer sandstones, of no great height or extent, resting
upon an uneven platform of the rhyolites, which are exposed on
either side of them. The most northerly of these outliers occurs to
the west of the village of Nausar, where there are a few small out-
crops of the rhyolites. The sandstones are rather coarse grained
with numerous strings of small well-rolled pebbles of white and yellow
quartz, and a very few derived from the rhyolites. I could find no

(74)

DETAILED DESCRIPTIONS OF ROCKS. 78

fossils anywhere in these sandstones, but they resemble the sandstones
of Barmer so closely that there is little doubt that they belong to the
same group. The sandstone of the two outliers to the south, near the
villages of Sanpa and Sarnu, is precisely similar. They all dip at low
angles, from 7 to io degrees, in an easterly direction. Оп the east
side of the Sarnu outlier there is a large boss composed of a dark
grey basic rock containing zegerine-augite, sanidine and sodalite with
perhaps nosean, resembling a tinguaite from the neighbourhood of
Montreal)! and is thus quite different from the material of which
the ordinary basic dykes traversing the rhyolites are composed.
From its position it appears to be intrusive in the sandstones, but
the actual junction between the two rocks is concealed by sand.

Thirteen miles to the north of Nausar, near the village of Khatu,
there is a chain of small hills running from south-west to north-east
for a distance of about seven miles. These are all composed of
rhyolites, a reddish brown highly porphyritic variety with numerous
crystals of pink felspar.

To the west of the outliers near Nausar the country for a distance
of about 25 miles is entirely covered with sandhills, among which
there are no outcrops of solid rock. Beyond this again, to the west
of Barmer, there is a larger area, extending from Bonthia in the
north to Chotan in the south, a distance of 40 miles, and from Barmer
westwards to the edge of the map, a distance of about 27 miles, in which
numerous rock islets are scattered about protruding from the undu-
lating surface of the sand in a manner which suggests the summits
of a large mountainous island partly submerged beneath the sea. By
far the greater portion of these hills are composed of the Malani
rhyolites, and these do not present so great a variety as those occurring
on the eastern side of the desert about Jodhpur and Siwana, but con.
sist for the most part of compact dark grey, sometimes black, glassy

or pitchstone like lavas containing porphyritic crystals of white or

1 Rosenbusch, Mikr. Phys. Mass. Gest., 1896, p. 483.
(297557

26 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

pink felspar and grains of quartz. Flow-structure is frequently met
with among them, and some of the flows are spharulitic. А reddish
brown, more strongly porphyritic rhyolite is found in places, especially
in the neighbourhood of Barmer itself.

There do not appear to be any beds of tuff intercalated with the-
lava flows, and it is generally impossible to make out any regular
bedding among them. They seem to have been erupted from a net-
work of fissures and to have been heaped together without any detinite
arrangement. No trace of anything like a vent is,to be seen any-
where. Near the village of Jesai, about ten miles west of Barmer, a
thick bed of conglomerate, consisting of well rolled pebbles of the
rhyolites imbedded in an ashy matrix, is interstratified with the flows.
The bedding of this is inclined to the west-south-west at an angle
of 30°.

The western portion of the large hill at Jesai, rising to an altitude of
2,073 feet above the sea, consists of a rather coarse hornblendic granite
without mica, similar to the granite of Siwana. The relations of this
granite to the rhyolites are not so clear as they are in the Siwana
country, for no sections were found in which the granite could be seen
to throw off veins into the rhyolites, while on the other hand the latter
in a few places appeared to be intrusive in the granite, I have already
pointed out! that the granite of this area was probably intruded into
the lavas before the period of volcanic activity came to an end, and
thus it came to be pierced by dykes of the rhyolites.

The same granite occurs again in the hill west of Taratra, ten
miles south of Jesai, and clear sections of the junction with the rhyo-
lites are exposed at the head of a ravine just west of the village.
Here the granite is distinctly intrusive, sending off veins and tongues
into the rhyolites; it also includes masses of the latter. Тһе western
portion of the hill is composed of rhyolite dipping away from the
granite towards the north-west. /

1 Supra, p. 24.
(20050)

DETAILED DESCRIPTIONS OF ROCKS. 77

The large hills at Chotan, which is situated just outside the south-
western corner of the map, are all composed ofa similar granite,
traversed by numerous east and west dykes of basic rock. A few
masses of rhyolite are seen in contact with the granite of the hill
north-west of Chotan, and are apparently included in it.

The isolated hill at Radhana, 27 miles west of Barmer, is also
composed ofthis coarse grained granite. Here it is broken through
by several broad dykes of a dark coloured eurite indistinguishable in
appearance from the rhyolites.

The mode of occurrence of the Barmer sandstones at Barmer itself
has already been described." A clear section showing the uncon-
formability between the sandstones and rhyolites is exposed in a
small hill at Lunu, about five miles north west of Barmer. Неге the
sandstones dipping to the north-east at 26? are banked up against
and cover up an old ridge of the rhyolites, which runs from north to
south through the middle of the hill. Тһе sandstones are also exposed
in several places on the plain to the north. At Bhadres they form a
low rise entirely covered with blown sand, but the sandstone is found
in wells. At Sondri and Bonthia they rise above the sand into low
scarped hills dipping in an easterly direction at low angles.

! Supra, р» 33.

78 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

CHAPTER VII—PETROGRAPHICAL NOTES.

I. Malani Rhyolites.

I have not yet been able to work out in detail with the microscope
the large mass of material collected during my three seasons' field
work in Western Rajputana, but I think that I have examined a
sufficient number of specimens to givea general idea of the composition
and structure of the rhyolites.

That these rocks were exceedingly siliceous was noticed by
Mr. Blanford, the hardness of fresh specimens being often equal
to that of quartz, so that they are not scratched by a knife. Tie
siliceous character is confirmed by microscopic examination, the
groundmass always consisting to a great extent of free quartz. The
groundmass consists essentially of an intimate mixture of felspar and
quartz, with as a rule a good deal of magnetite in minute grains, and
dusty matter. Hornblende in the form of minute rods or acicular
crystals and grains also occurs in the groundmass of many specimens.
Augite perhaps occurs in one or two, but owing to its generally de-
composed condition, I have considerable doubt in identifying it; and a
yellowish green chloritic mineral is common. I have not found mica in
any of the lavas, but magnesian mica occurs in minute flakes in the
matrix of one of the tuffs (No. 11:500)!. Apatite is also sometimes
present in small quantity. Phenocrysts of quartz and fe!spar occur in
nearly all the lavas, but are in a few cases entirely absent.

The forms of structure exhibited by the groundmass are very
various. Fluidal, perlitic and spherulitic structures are common,
those in fact that are peculiar to rocks that have flowed ina molten
condition at the surface. Vesicular structure is sometimes met with,
but isnot very common, probably because such acid lavas as these
were in a very viscid condition when molten; and some of the flows

! These numbers refer tothe entries in the Rock Register of the Indian
Museum.

(7 San)

PETROGRAPHICAL NOTES. 79

have a very scoriaceous appearance. The different structures of the
groundmass will be described more in detail further on.

The colours of the lavas also vary to a great extent. А rich brown,
often with a reddish or purplish tinge, is perhaps the most common,
but many are bright red, blue, green or almost black, and a few are
white or light grey. Thecolour appears to be due in most cases to the
presence of oxides of iron, but in the green and yellow varieties to the
abundance of hornblende or chloritic minerals they contain. The
tuffs are generally light coloured, in various shades of pink, buff, and
green.

The specific gravity of the rhyolites varies from 2°42 in the softer
altered specimens to about 2:76 in unaltered varieties. That of some
of the tuffs ranges as low as 2°33 and very rarely rises above 2:40. An
analysis of the values found for 167 specimens, including tuffs, gives

the following results ===

Specific Gravity.

Below 2'5 23 specimens оғ 1277 рег cent.
25—2'55 32 » 191 »
2455-26 - 28 55 170 s;
2°6—2°65 41 cb 22:67 5
2:65—2'7 29 » 1:3 ә
Above 27 14 5 83:55

From this it appears that the greater number of the specimens
approximate in specific gravity to that of quartz, 2°65.

The quartz phenocrysts in many cases possess very perfect сгуз+
talline outlines in the form of hexagons and octagons, but more
frequently the original shape has been destroyed by corrosion. This
frequently results in the production of fantastic forms, inlets, or tongues
(Einbuchtungen) of the groundmass projecting far into the interior
of the crystal (P1. IX, fig. 1). Іп some cases the corrosion has taken
place more rapidly along zones concentric with the outer boundary of
the crystal; avery perfect example of this is shown in fig. 2, Pl. IX,
Occasionally the included portions of the groundmass, without visible

(5799)

бо LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA-

connection with the surrounding magma, have a more or less welí
defined, hexagonal outline, but in most cases their outlines are
rounded and they are evidently-sections of inlets.1 In one or two
cases the quartz crystals appear to have been partially melted and
drawn out into strings along the lines of flow (Pl. IX, fig. 3).

A very beautiful and interesting phenomenon is exhibited by the
quartz phenocrysts in several specimens, and is illustrated by figs. 4, 5
and 6, PL IX. This consists in a growth of the crystalto a greater or
less distance into the surrounding groundmass, either during or sub-
sequent to the consolidation of the rock. In allcases the secondary
quartz surrounding the original phenocryst is in optical continuity
with it, and extinguishes simultaneously with it between crossed
Nicols. Sometimes the secondary quartz forms irregular patches,
looking like small tufts of cotton wool, only partially surrounding
the phenocryst. In this particular instance the hexagonal outline
of the original crystal is very distinct. In other cases these
patches are united into a continuous area surrounding the crystal
sometimes with irregular boundaries as in fig. 4, and sometimes
following the outlines of the crystal pretty closely as in fig. 5.
In one example the crystal appears to have been broken into two
halves, lying in a slightly different optical relation to the plane of
polarised light traversing them, so that they give slightly different
colours between crossed Nicols; each portion has its concentric area
or “court ” enclosing it, each polarising in the same colour as the
portion of the crystal it surrounds, and the two “courts " meet along
a line about midway between the two halves of the crystal. With a
high power the details of the structure of these " courts ” can be easily
examined. The secondary quartz ramifies out from the edge of the

1 It appears to me that the hexagonal inclusions of the groundmass may
also be sections of “inlets ” that have corroded the crystal along zonal lines, and
that their presence does not afford a convincing argument for the contemporas
neous formation of the phenocrysts, as suggested by Zirkel (Rosenbusch. Mikr.
Phys. Massig. Gest., pp. 52, 99)-

( 80 )

PETROGRAPHICAL NOTES. 81

phenocryst in among the minute crystals of felspar forming the
remainder of the groundmass, giving rise to a minutely micropeg-
matitic structure as in fig. 6. This structure appears to me to
throw some light on the question of the origin of the groundmass of
rhyolites and quartz porphyries and will be referred to later on in the
discussion of the groundmass.

Inclusions of various kinds are tolerably numerous in the quartz
phenocrysts. They include gas pores, which are often arranged
in lines parallel to the cracks traversing the crystals ; and glass
inclusions, usually with a fixed bubble. These latter sometimes
possess hexagonal outlines, but are more usually rectangular with
rounded corners. Occasionally a faint asterism is perceptible in
them. Cavities containing liquid are also not rare, and these generally
contain a movable bubble, which when the cavity is of sufficiently
small dimensions, and the bubble is also small, may be seen under a
high power to be in constant spontaneous motion. The inclusion of
portions of the groundmass in the quartz phenocrysts has already been
alluded to.

The felspar phenocrysts do not as a rule show signs of corrosion,
but frequently have well defined crystalline outlines; this suggests that
the felspars may be phenocrysts in the true sense of the word, that is,
that they have been formed Zu sítu in the molten magma, while the
quartz phenocrysts may have been floated in from some deep-seated
coarsely crystalline mass, pierced by the rhyolites, and undergone
corrosion in the process. In the phenocryst shown in fig. 2, Pl. X,
the felspar possesses perfect crystalline outlines, while the quartz is
apparently merely the skeleton of a previously formed crystal. I have
never found any trace of secondary growth at their edges, such as is
so often exhibited by the quartz grains. Sometimes the felspars possess
well defined simple twinning or consist of aggregates of interpene-
trating individuals, a structure that is very distinctly brought out in
polarised light (Pl. X, fig. 1). The great majority of them are un-
doubtedly orthoclase, and many have the “glassy” appearance of

(2977)

82 LA TOUCHE: GEOLOGY OF WESTERN RAjPUTAKA.

sanidine. Very often, however,,a more or less distinct striated twi-
ning is developed in them somewhat similar to the twin structure is
microcline, but without its reticulated appearance. The striae some-
times lie parallel to the direction of schillerisation of the felspars,
and it is possible that their development is of secondary origin and is
connected in some way with the decomposition of the mineral. Inone
case (No. 11:556) some of the felspars consist of undoubted oligoclase.

Very commonly the whole of the felspar phenocrysts have been
converted into white powdery kaolin, which has hardly any action on
polarised light. In other cases they are much clouded by dusty matter
and lines of inclusions, the products of schillerisation. The inclusions
are sometimes arranged in zones parallel to the edges of the crystal.

Phenocrysts of hornblende occur in a few specimens, principally
from the range south of Jasol. They are generally in the form of
irregular patches consisting of aggregates of minute microlites, but
some show well defined crystalline outlines. They are generally
associated with much opaque magnetite, and are frequently altered
into a light yellow chloritic mineral.

The slide cut from specimen No. 11:564, from the range south of
Jasol, contains a well defined crystal giving brilliant colours in polarised
light, and with a high angle of extinction, which may be augite.

At first sight in many cases the groundmass of these lavas appears
to be entirely glassy and homogeneous, but the application of polarised
light shows that it is always crystalline, though the size of the crystal
varies greatly, from the most minute grains, such as can be detected
only with a very high power, to an almost granitic holocrystalline
structure. In the most common varieties the quartz appears to have
acted as a matrix, in which minute crystals of felspar are imbedded,
sometimes irregularly, giving rise to a structure similar on a small
scale to the ophitic structure of some basic rocks; in other cases more
or less parallel to each other, forming an extremely minutely grained
micropegmatite (Pl. ІХ, fig. 6) ; or again arranged in radiating fibrous
aggregates ог spherulites. The minute microlites of felspar are often
( 82 )

PETROGRAPHICAL NOTES. 83

well shaped and have evidently grown freely in the surrounding
magma, but they are usually too small to allow of their species being
determined, though most ef them are probably orthoclase. Occasion-
ally one may be found which shows striated twinning.

In many of the specimens the groundmass breaks up on the
application of polarised light inte а more or less irregular mosaic of
light and dark areas (Pl. IX, figs. 4, 5), in which, when in a position of
extinction, the felspar microlites appear as dim points of light. That
the matrix of each of these areas consists of crystalline quartz is
evident when they are in contact with the quartz phenocrysts, for it
is then seen that the quartz of the phenocryst is in optical continuity
with the substance filling the interstices between the felspar microlites.
The original quartz of the phenocryst and the “ secondary " quartz
of the groundmass extinguish simultaneously, the latter forming the
closed areas or “ courts ” surrounding the phenocryst, already described.
It is possible that each of the areas forming this “quartz mosaic," as
it may be called, has been built up round a previously existing granule
of quartz, introduced, like the larger phenocrysts, from outside, though
such a central granule is not always visible in the slide, owing to the
direction the section has taken. The size of the areas appears to
depend upon the number and distribution of these granules; where
they are numerous and close together the mosaic will be proportionally
fine grained. The quartz composing any individual of the mosaic
appears to bave grown outwards until its development was arrested
by contact with the surrounding individuals. Thus, in cases where
the mosaic is composed of small areas, the “ court" surrounding a
quartz phenocryst, even though the latter isa large one, is propor-
tionately narrow. Conversely, a small phenocryst may be surrounded
by a broad “ court " if the mosaic composing the groundmass consists of
large individuals.

It is a question whether this mosaic of quartz grains was formed at
the time of consolidation of the rock, or whether it is a result of second-

ary devitrification of an originally glassy magma. I am strongly

CESS)

84 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

inclined to think that it is an original feature, otherwise it would be
difficult to account for cases where the secondary quartz does not
surround the whole phenocryst. If this growth had taken place after
the consolidation of the rock, there seems to be no reason why it
should not have spread through the whole of the groundmass, as it has
done in some iustances (Pl. IX, figs. 4, 5). In other cases also, for
instance, No. 11:537 (РІ. 1X, fig. 2), there is no sign cf such a growth
round the quartz phenocrysts and yet there is no reason to suppose
that these flows have been subjected since their consolidation to
different conditions. There is no evidence of their having been greatly
disturbed or folded to such an extent that some of them might have
been acted upon by great heat and pressure, to which others were not
subjected. І have observed that some of the flows which show no
trace of the formation of а “ mosaic", bear evidence in the shape of
included fragments of rhyolite probably showered down upon them
from above, that at the time of their eruption they were at once ex-
posed to the atmosphere, and therefore presumably cooled more rapidly
than the flows which do not contain such fragments, but which do
possess the mosaic structure. Thus the formation of this structure
seems to have depended to some extent at any rate on the conditions
under which the rock solidified. For this reason, although I have
called the quartz of the “courts” surrounding the phenocrysts
* secondary," І do not consider that it is “ secondary’ in the sense of
having been produced by devitrification subsequently to the consolida-
tion of the rock, but merely that it was of secondary growth in-com-
parison with the original quartz of the phenocrysts.

It is difficult to say why the groundmass of some of the lavas
should present the appearance just described, while in others instead
of the “ quartz mosaic" we have a microcrystalline aggregate composed
of minute but perfectly distinct crystals of quartz and felspar. Pro-
bably this variation in the character of the groundmass is due to some

difference in the conditions and rate of cooling, or perhaps, in the

( 84 )

PETROGRAPHICAL NOTES. 85

microcrystalline variety, to the absence of the foreign particles of quartz
which appear to have started the growth of the “ quartz mosaic.”

A censideration of the appearances presented by the fluidal struc-
tures so beautifully developed in several of these rhyolites (РІ. X,
figs. 3—5) seems to me to lead to the same conclusion that I have
deduced from a study of the * quartz mosaic," that is to say, that the
rocks at the time of their consolidation were not in the condition of
a homogeneous glass, which has become crystalline by subsequent
devitrification. In allthe slides which exhibit this structure we find
alternate bands of exceedingly fine grained, and more coarsely crys-
taline matter. The coarse grained bands are never continuous for
any considerable distance, but are always lenticular, while the fine
grained bands stream round these lenticular’ areas just as they do
round the phenocrysts. If the coarse grained lenticles are closely
examined, it will be seen that the crystals composing them have
grown inwards from either wall, and that there is a well marked line
along the centre, where the crystals from either side meet; in fact
the structure is exactly similar to that of an ordinary mineral vein.
In some cases, as in No. 11:565 (РІ. X, fig. 3), the substance filling the
central space of the lenticle is bornblende, and in others, it appears to
be either magnetite or a mixture of magnetite and hornblende. The
crystals projecting from the walls are also frequently hornblende,
sometimes in rod shaped microlites and sometimes in radiating
bunches of delicate needles (PI. X, figs. 3, 4). It appears therefore
that the magma filing these lenticles contained a larger amount of
ferromagnesian material than the body of the rock, and was presuma-
bly in a more liquid condition. This would account for the more
perfect growth of the crystals in these areas, just as the growth of
the crystals in a -cavity filled with concentrated mineral solution is
generally more perfect than in the surrounding rock. On the other
hand, on the assumption that the rock was originally a homogeneous
glass, it would be difficult to account for the presence of these lenticles.

(218547)

80 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

That they were formed, or in process of formation, while the surround-
ing magma was ina more or less viscous condition is proved by the
manner in which this * flows" round them; and their dimensions pre-
clude the idea of their having been originally cavities, which have been
subsequently filled with minerals leached out from the surrounding
rock, for they are sometimes several inches long and half an inch or
more in width. If they had been cavities, we should expect to find
spaces in the centre of them unfilled with mineral, and I have so far not
found anything of the kind. True cavities filled with chalcedony or
other secondary mineral do occur sometimes, but they present an
appearance very different from the lenticular bands in the fluidal rocks.

Some few of the specimens I have examined exhibit a very well
defined perlitic structure. This is especially well developed in No.
11494 (PI. XI, figs. т, 2), froma flow in the neighbourhood of Jodhpur,
and is associated with minute sphaerulites. No. 11:530 also shows this
structure very clearly. In No. 11:532 (Pl. X, fig. 5) the perlitic cracks
are concentric with the quartz phenocrysts and sometimes extend into
them from the groundmass. The perlitic structure in all of these is of
the ordinary kind, but the beautiful variety shown in portions of
No. 11'523 (Pl. X, fig. 6), merits a further description. In this case
the cracks have opened to a small extent, and are lined on either side
by minute crystals of quartz, projecting inwards, and meeting along a
well defined line in the middle of the fissure. The spaces between the
cracks are filled with granular quartz, sometimes clear, but usually
stained a deep brown. This structure is identical, so far as can be
determined from the description, with that described by Rosenbusch
in the pyromeride of Wuenheim in Upper Alsace." This specimen, which
was collected in the hills to the west of Nagona, about 33 miles west-
south-west of Jodhpur, also contains large brown sphzrulites, some of
them as large as a hazelnut.

Spheerulitic structures are of very common occurrence in these rocks

Rosenbusch, Mikr. Phys. Massig. Gest., p. 83.

PETROGRAPHICAL NOTES. 87

and often very beautiful in appearance. In some, as for instance
No. 11578, the spherulites are isolated globules, scattered about in the
body of the rock and giving a dark interference cross between crossed
Nicols. In others, the different individuals forming the ‘quartz
mosaic" each contain in their interior a radiating bunch of minute
crystals, so that between crossed Nicols a number of little black crosses
make their appearance revolving as the Nicols are rotated like so many
minute wheels. In these cases the mineral forming the radiating
aggregates isfelspar. In some others again minute needles of horn-
blende are intercalated among the felspar crystals, giving rise to the
beautiful sphzrulites seen in No. 11:563 (Pl. XI, fig. 3). In this speci-
men, where the sphaerulites abut against a quartz phenocryst, the quartz
filling the interstices between the hornblende and felspar needles is, for
a short distance frem the edge of the phenocryst, in optical continuity
with it. A sphzerulitic structure of this kind also occurs along the
edges of the more coarsely crystalline bands in those rocks that possess
flow-structure (Pl. X, figs. 3, 4), and in the latter specimen perfect glob-
шат spherulites occur in the middle of the broader bands. The large
spherulites in the specimen No. 11523, described in the last paragraph,

- are often broken across, and fragments of them lie scattered about in all
directions in the body of therock. In this rock they generally have a
quartz grain atthe centre.

Among the specimens collected in the Boulder bed of the Salt Range
by Mr. Middlemiss and described by him in the Records of the Geo-
logical Survey? there is one which corresponds very closely in appear-
ance with some of the rhyolites of Western Rajputana. -This is
No. 8473, which is almost identical with No. 11512 from my collec-
tions from the group of hills near Agolai. The variable structure of
the groundmass, which is strongly fluidal, described by Mr. Middlemiss
is exactly repeated in my specimen, and the boulder from the Salt

Range might have been broken off a portion of the same flow. It is

! Rec. Geol. Surv. Ind. Vol. XXV, Pt. т, p. 29.

88 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

also very similar to Nos: 11:508 and 11:532, the first of which is from
the same group of hills, and the other from the neighbourhood of
Thob, at the south-western end of the chain of hills in which the Agolai
group is situated. ;

The felsites of Tusham hill described by Col. McMahon,
and compared by him with the rhyolites of Barmer and Pokaran
collected by Mr. Blanford,? differ from the latter in containing mica
among the constituents of the groundmass, and although the structure
is very similar, the presence of this mineral makes it more than doubt-
ful whether the Tusham rocks are identical with the Malanis.

Through the courtesy of Dr. Callaway, who has devoted much
time to a study of the pre-Cambrian rocks of Great Britain, I have been
enabled to compare these rhyolites with a few slides cut from the
ancient devitrified pitchstones and perlites of the Wrekin in Shrop-
shire, which were microscopically described by Mr. S. Allport. The
similarity in the structure of the groundmass in the two sets of rocks
is very remarkable, and indeed it would be difficult, if not impossible,
if the specimens from the two localities were mixed together, to pick
out those from the Wrekin from among the Rajputana rocks. The
identity is especially striking in a specimen from Lyd’s Hole, which
shows the peculiar structure of the groundmass that I have designated
by the name of * quartz mosaic." The spherulitic and other structures
too in other slides are exactly similar, but perhaps they are more clearly
defined in the Rajputana specimens, since these have not been subjected
to so great an amount of disturbance and crushing as the Wrekin rocks.
It would of course be rash to conclude that this similarity implies any
strict contemporaneity between the volcanic outbursts in two localities
so widely separated ; but when we consider that the Malani rhyolites
were poured out in pre-Vindhyan times, it is probable that there is no
very great disparity in age between them.

1 Rec. Geol. Surv. Ind., Vol. XVII, Pt. 3, p. 108.

2 Ibid, Vol. XIX, Pt. 3, p. 161.
3 Quart. Journ. Geol. Soc., Vol. XXXIII, p. 449.

(20651)

PETROGRAPHICAL NOTES. 89

2. Tuffs and Breccias.

The tuffs associated with the rhyolites are easily distinguishable
from them in the field mainly by reason of their lighter colours, their
mode of weathering, and their undoubtedly bedded aspect. In many
cases the larger fragments and lapilli they contain stand out con-
spicuously on the weathered surface of the rock, Under the microscope
the matrix is hardly to be distinguished from the groundmass of some
of the rhyolites, and they are evidently formed of the same material,
blown into dust and subsequently consolidated by pressure. The pre-
sence of fragments and lapilli of quartz and other minerals as well as
fragments derived from previously consolidated flows is sufficient proof
of their clastic origin. Опе of the tuffs, No. 11:500, contains numerous
flakes of brown mica ; this is the only instance in which I have found
this mineral associated with any of the Malani rhyolites.

The breccias usually occir in ienticular bands intercalated with the
lava flows. They consist of irregularly shaped angular fragments of
various sizes derived from previously consolidated flows imbedded
in a more or less opaque paste. The condition of the fragments
affords further argument in support of the contention that the crys-
talline structures developed in the groundmass were original, that is,
formed at the time of consolidation, and are not due to subsequent
processes of devitrification ; for in one and the same hand specimen of
breccia fragments may be found which exhibit each of the struc-
tures | have described, “quartz mosaic", microcrystalline and flow-
structure, which must have been developed in them before they
were broken up and included in the breccias. In one case, however,
in a bed of breccia extending over a considerable area in the low
ground west of the group of hills near Nagona, the included fragments
possess a structure, which may be due to devitrification developed in
them after they were included in the matrix. The fragments are mostly

( 89 )

go LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

rectangular and triangular or wedge shaped chips of glass, in which
bundles of delicate fibres have been developed, projecting inwards
from the edges and at right angles to them, not meeting in the centre
but leaving a clear space along which there is usually a line of black
granules (Pl. XI, figs. 4, 5). Some of the chips contain minute globu-
lites round which the fibres curve as shown in fig. 5. The
structure is exactly similar to that developed in a piece of artificial
glass exposed after its first consolidation to great heat, an example
of which is given in Professor Bonney’s anniversary address to the
Geological Society of London in 18851 Тһе matrix of this breccia,
No. 11524, is a fine grained microcrystalline rhyolite, and ‘there is no
doubt that it was molten when the chips of already solidified glass from
another flow were showered intoit, and that they were then partially
devitrified by the heat of the surrounding molten mass.

The volcanic ash, No. 8:480, described by Mr. Middlemiss in the
paper above referred to, from one of the boulders in the Salt Range
boulder bed, is very similar to one of the tuff beds at Korra, No.

І1:501.

3. Granite.

The granites associated with the Malani rhyolites do not present
many features of particular interest under the microscope. The Siwara
granite contains an abundance of actinolitic hornblende, usually of a
bright green colour but sometimes with a bluish tinge ; the pleochroism
is usually very strong. It is commonly interstitial, but occasionally
occurs in idiomorophic crystals, especially in the veins and dykes pro-
truded from the main mass into the surrounding rhyolites. The felspar
and quartz frequently form a micropegmatitic intergrowth or granophyric
structure of great beauty, and the rock is then indistinguishable from
the specimen No. 8472 described by Mr. Middlemiss in the paper

1 Quart. Journ. Geol. Soc., Vol. XLI, p. 92.

PETROGRAPHICAL NOTES. 01

above cited on the Boulder bed of the Salt Range. There seems to
be a singular dearth of accessory minerals in this granite ; even magne-
tite is rare.

At the contact between the granite and rhyolite there is usually a
- considerable development of hornblende in the latter. At times this
takes the form of a growth of comparatively large nests of hornblende
which have apparently included portions of the groundmass. Along
the actual line of junction a row of small hornblende crystals pro-
jects into the granite, evidently formed before the mass of the latter
began to solidify (Pl. XI, fig. 6).

The Jalor granite differs from that just described mainly in con-
taining mica as the principal ferromagnesian constituent instead of
hornblende. "There is also a fair proportion of plagioclase felspar as
well as orthoclase, The mica is of two kinds, muscovite and biotite
The former predominates in a specimen from Manpur near Pali, No.
12:258, while biotite alone occurs in the granite of Jalor hill, No.
117716.

4. Basic Dykes.

I am indebted to Mr. Holland for the following description of the
specimens collected from the dykes in the area surveyed. The ordi-
nary dykes traversing the rhyolites and granites, when unaltered, like
the rock composing the large dyke to the south of Jalor (No. 11715)
are olivine dolerites or diabases, and consist of “ plagioclase felspar,a
“ basic variety giving extinctions near labradorite (bytownite) ; olivine
“in isolated crystals and in clusters partially serpentinised, but with-
“out ‘reaction borders’ at their junction with the plagioclase ; pale
“red brown augite, forming sub-ophitic intergrowths with the felspar
“апа olivine ; apatite in numerous well shaped prisms ; opaque black
“iron ores in large lumps with crystalline shapes, and a small quantity
“of brown biotite often associated with the iron ores." The rock is
medium or coarse grained in the centre of the dykes, but near their

(2091)

92 LA TOUCHE: GEOLOGY OF WESTERN RAJPUTANA.

edges passes into an extremely fine grained selvage, often quite glassy
in appearance. Where it has been much decomposed, as in No.
11:548, the olivines һауе almost entirely disappeared and the augite is
to a great extent replaced by hornblende. The specific gravity varies
from 3:14 in No. 12:312, which contains a large amount of unaltered
olivine, to 2°72 in the most altered varieties. About half of the
specimens examined have a specific gravity of 3:00.

The rock from the dyke or boss mentioned on p. 75 as probably intru-
sive in the Barmer sandstones near the village of Sarnu, on the eastern
edge of the Barmer desert, is very different in composition from that
just described and evidently belongs to quite a different period of
volcanic activity. Mr. Holland says: “ Macroscopically this rock
“ (No. 13:803). is grey, with porphyritic crystals of sanidine and zgerine
“augite, sometimes reaching (in the former case) about 5 inch across
“but more offen } inch, E inch, or less. The weathered surface shows the
“ characteristic pitted surface of these rocks by removal of the soluble
‘“felspathoids. The constituents are idiomorphic egerine augite,
“sanidine, sodalite (and? nosean\, sphene, apatite and melanite in a
“fine grained matrix of sanidine and nepheline.

“ Felspar. Sanidine in porphyritic crystals, fairly fresh and as
‘“numerous lath shaped crystals in the groundmass. Often in Carlsbad
“twins. lrregularly shaped inclusions of a colourless isotropic decom-
“ posable mineral are common.

“ Pyroxene. /Egerine augite variety in porphyritic crystals and
“as smaller granules. Zoned with zonal extinctions and hour-glass
“structure between crossed Nicols. Pleochroism strong, a green, b
“yellowish brown, с greenish yellow. Extinction 31° (c: a): or 59°
* (c: a); occasionally twinned. Margins often rugged and of different

` “colour.

“ Sphene in numerous well shaped colourless crystals, twinned.

“ Melantte. Rugged brown lumps, very few in number.

“ Sodalite (and? nosean). Well shaped crystals; dirty brown and

( 92 )

PETROGRAPHICAL NOTES. 93

‘darkened at borders, isotropic, often decomposed with formation of
“fibrous zeolites; rectangular meshwork of dust lines occasionally
“ shown.

“Rounded masses of tufted zeolites with clear apatite crystals
‘probably represent patches where sodalite was once concentrated.
“The products of decomposition include cadezte.

* Much of the colourless groundmass is decomposed by hydrochlo-
“тіс acid with formation of gelatinous silica in which the insoluble
“ granules (гесегіпе, etc.) are imbedded. Treatment of the powdered
“rock with nitric acid is attended with effervescence, and the solution
“gives reactions for chlorine (strong), sulphuric acid (very faint),
“alumina (strong), and phosphoric acid (strong).

“Opaque iron ores present only in very small quantities and as
“very minute grains.

** The rock appears to resemble a tinguaite from the neighbourhood
* of Montreal. (Rosenbusch, Mass. Gest., 1896, p. 483).”

The specific gravity of the rock is 2:69.

At the same locality is found a dense nearly black basaltic rock
(No. 13,804), containing plagioclase felspar, pale red brown augites
and a large amount of iron ore. The specific gravity of this rock is
323. It approaches some of the Deccan traps in composition. The
relations of this rock with the tinguaite could not be made out, as the
junction is concealed by sand.

( 93 )

INDEX.

ss
A

Abur group : c . . C D E
Actinolite, in Siwana granite j 5 o .
JEgerineaugite . . : . А . e
Aggregates, felspar . с G © ° А
Agolai, Malani series at . c . о .
Ajiana, granite near . . . o E c
Allport, S., Wrekin rhyolites . : ° б .
Amir shingle beds : 5 o . . gi
Ammonite bed of Kuchri ° ° S o e
Apatite—

inrhyolites ` А . : . °

in dyke rocks с . . > А .
Aravalli region—

useful minerals of . С o . . .

geology of . S . . с . °
Aravalli rocks . c . г E c 3

North of Erinpura . . . o
Aravalli Series, relations between—and Malanis А

5 е апа Vindhyans

Ash beds—

at Korna = . с . в . .

near Patodi . ^. о 4 С . .

near Kuip . . 5 . o 5 .

at Siwana B с с о . о

in hill N. E. of Siwar > С S . :

atGoendla . 5 : c .
Ash, volcanic, in boulder bed of Salt Range o o
Asterism, in inclusions in quartz о . . .
Augite—

in groundmass of rhyolites E , c .

phenocryst in rhyolite — . c : с

in dyke rocks Е . . é © о

В

Bakhal, concretionary rhyolites at .
Balasar (Shergarh dist.), Vindhyans ese Ми at

PAGE.

7» 35

‹ 90
75; 92

2. 9B
47

. бі
o REI
2447539
3) 35

d 78
91, 92
5 6
é 6
. 16
әл 73
3 I9
° 20
А8,
. 50
214159
» бо
e бї
4.70
. 90
0581
о,
92
91,92

D 79

SECHS

96 INDEX.

Balotra, sandhills near à О o ;
Balu, granite near о o c B
Baorli, Malanis at 5 On . D

Bap, boulder beds of . . . . .

Вагтег агеа—

sandhills of < б “ ° . e
granite of c . . . o о
rocks of е : . : d .

Barmer, gypsum near . à . o с

Barmer sandstones E . . . 6
plant remains İn ғ . О
description of с 5 . . 2
cretaceous 5 ` 6 o o с
outliers of c с ° .

relations of—to Malanis . b .
Basalt, associated with boulder beds of Pekara

Basic dykes— . е . . D D
at Jasol - . . : . .
іп Nagar range : . e .
petrology of . . . ] .
Basic rocks interstratified with [ESSO о 5
Bastua, inliers of rhyolites near б > о
Bedesir group . . . . о
Bhadrajun range . . . . . .
Bhander sandstone . б E S .
Bhaonagar, schists near . . .

Bhaori, nodular rhyolites at . .
Bijli, hornblendic granite at . . .
Biotite in Jalor granite

Blanford, W. T., journey through deer . .

boulder beds of Pokaran . > . e
origin of salt . о . . . о
Blown ѕапа - 5 . О ;
Bonney, Prof., devitrified structure . E o

Bonthia, outlier of Barmer sandstone at .
Boulder beds —

basalt associated with 5 5 . .

of Bap апа Pokaran . . . .

of Salt Range . . . .
Breccias —

mode of occurrence of 5 с 5 5

at Dugar 5 4 3 . e -

31
42.
4, 37
90
77

25
31

32, 87, 91

23
47

INDEX.

Breccias—

near Nagona . о б . 5

at Thob . . o А

in Nagar range . o , .

in ridge north of Кир . .

near Айапа . . . © .

interstratified with rhyolites .

near Golia . . . .

indurated—at Pati . . о z

in Bhadrajun range . e .

petrology of . . o

devitrified fragments іп . .
Bubbles, movable, in liquid cavities . .
Building stone at Jodhpur . :

C

Calcareous tufa . А e .
Calcareous schists—

of Godwar . . . . .

of Makrana . S . . .
Calcite—

іп Godwar œ D . . .

in nodular rhyolite . . А .

Callaway, Dr. C., Wrekin rhyolites
Carbonate of lime, particles of—in sand
Cardium, in Barmer sandstone z
Carter, Dr. H. J., Geology of India
Cavities, liquid—in quartz .

inrhyolites . . . :
Chalcedony in rhyolites . . .
Chanod—

section near . . ‘ .

hills near . . .

Chasm formed by weathering out of dyke

Chondrai, hill at . 5 е о
Chopasni, conglomerates at . .
Chotan, granite at o . o
Climate, changes of . : .

LI

66

98 INDEX.

PAGE.
Colours— :
ofrhyolits . 2 . > o 5 c 5 a о „20,79
of tuffs . ° . . o о = : . . o . 79
Columnar jointing of rhyolites— . о . e Së aie . .23,47
at Korna o 5 . 5 5 o B 5 ° 5 518
at Nagona œ . : . . . g . . . . 49
at Tesingri e o С . д о б о 5 : « 49
at Thob a . . . . . . . . . 50
Concretionary rhyolites at Bakhal . о . e . . < . 79
Cone, conjectural volcanic—near Nagona . С 2 : . a St
Conglomerates—
sub-recent о 2 c o c 9 o О . II, 14, 36
interstratified with obt . А . 5 S „21, 23, 58, бо, 62
at Siwana . c . . . | . . Е Або
near Айапа . . S . E . . r © . 2262
at Siner о . : : . А . . б . 62
near Jesai . . о . . . . . e c О.
between schists and Malanis . 5 . o б . o 2 20
between schists and Vindhyans . . . . 5 . 25420
between Malanis and Vindhyans . o o o А 5 222127,
at base of Barmer sandstones . . . 5 . . . 42-038
at base of Vindhyans near Jodhpur . e S о о : А5
Contact of rhyolite and granite . . . : . ` 5 V OI
Corrosion of quartz phenocrysts . . . . . . . . 79
“Court” surrounding quartz phenocrysts . . : © . 80, 83
Cretaceous sandstone at Barmer . . . . . . : 5 52
Crystalline rocks . : . : . : . . . tS
Cup and ball structure in columnar faves . А . . . . 49
Current bedding—
in sandstones . : : . . . . 4 . ó 2 529
іп tuffs ғ . . . ; A ^ Я : А 27 160
Cutch, foraminifera іп аце ONA А А e е 4 : , 39
D
Dandali, granite at 5 К А 5 e 5 . o 2 0
Darri, granite near с a A 5 . E . 5 ғ 215468
Deflation, effects of С c 5 E 5 . E E : A 155)
Delhi system 5 e 2 . 5 - 5 . S . a nf

Denudation in Malani period . C 5 . E . > . ZI

INDEX,

Deora, granite at . S С е o © ©
Desuri, marble near : o 5 а 5 o
Devitrification . . : . . E
of fragments in breccia. о .
Dhira, sphzerulitic rhyolites near . . .
Dicotyledonous leaves—
іп Barmer sandstones . о > : .
іп Lathi group . 6 . e e °
Didwana, salt lake at . А О . А B
Dolerite, intrusive in Malanis . S B О 6
Dolerite dykes—
at Jasol e . ` А ° б >
in Nagar range . c o o e °
іп ridge north of Kuip . . 5 А
at Siner о о . . o . с
Indrana range 5 o . o 5
near Chanod . S E c c . e
in granite c . . : . . >
at Jalor . 3 . a é ó . .
in Aravalli schists . . S . 5
Dugar, columnar jointing аё . А с . .
Dykes, basic © . . E . . e
age of . 5 5 . . . >
weathering of , . с > . . .
Dykes, eurite, at Kaonla о . >
» in granite, . D E ` .
» atRadhana . З о o 5 :
E
Einbuchtungen, inlets of groundmass in phenocrysts
Erinpura, hills near С . . . . о
Егіприга granite . . А . . А .
intrusive character of d . . . Я
relations to Aravalli rocks . . . е
іп Godwar . . . e E о °
Erosion of lavas . . С . . .
Eurite dykes—
at Kaonla . . о А 8 . c
in granite at Dandali e . 5 > .
at Radhana . . . 9 ° . .

99
РАСЕ.
56
КІЛ
o EK
о 7890
5 66
• 34
34
б 48
. 25
GH
53
D 53
62
63

SE DOE
. 71
319572
e 73
. 47
25,91
e 125
52,53
200169
64,74
024.
4 79
° 73
218,72
21718
72
4/ 73
20
. б;
о yf

09

False bedding in sandstones .

intufls . . . .
Felsites, Tusham hill , S
Felspar—

in Erinpura granite .

insand . E .

in groundmass of SES

phenocrysts . 4 e

in sphærulites . c .
Fissile rhyolite at Nagona .
Fissure vent . o o

Flows, scoriaceous character of
Flow structure—

at Agolai . О z
at Korna б 6

vertical, at Nagona 5
at Tesingri . S 5
at Thob o К с
near Indrana . 5 с

Chanod hills . 5 .
ас Malgarh . . .
іт Bhadrajun range .
in groundmass . .
іп fragments in breccias

Fluidal structure, see flow-structure.

Foliation of granite in veins
Foraminifera—
insand . . . >
in limestone of Cutch o
Formations, Blanford’s list of.
in Western Rajputana .
in Јаіѕаітіг . «
Fossils, doubtful—in Vindhyans
in Barmer sandstones
of Jaisalmir group .
foraminifera in sand
Fragments of lava in breccias
devitrified . 5
Frere, Sir H. Bartle, оп ОЛЕШ
Fuller’s earth 5 . .

PAGE,
28

• 69
. 8%
UNIO,
3250839;
+78, 82
ESSI
87

48

. 49
23

+ 47
. 48
- 48
о; 49
50

D 63.
- 167
. 68
70

85

« 89
. 69
+ 39
. 39
о d
* 16
« ^35
. 30
#1138;
Oi 3
. 39
. 80
ve 90
4

INDEX, IOI

G
PAGE,
Garah, Malanis at А О - . А E 5 E v ° 59
Gas cavities in rhyolite . о . ° . . ° ° o o an
Gas pores in quartz phenocrysts . ° с . . . . -- 81
Ghoriala, Zeugen near » . ° . . . o . 5 • 45
Glaciated boulders at Вар œ . . E о o o ; 732
Glaciated rocks at Pokaran . . ° . А © wwe с &
“Glacis ” of kunkur, formation of . © . 5 E . . 412,41
Glass inclusions іп quartz . . . . e o D ғ 40 91
Gneissose granite . E . . . . . e 2 . 718
at Sanderao . © б . . . . . . О 21208572
Goendla, ash beds at . А o B E о 5 о o 285870
Golia, breccias near . o . o . О 5 o б 2 65
Godwar —
Aravalli rocks їп œ B . . . : ° Š Я 28217
Erinpura granite in . o . e б . > . 19, 73
Gondwanas, suspected presence of—in Кајриќапа - ° ° © S 7
Granite—
undercut by wind . . . . e . e 5 o . YI
effects of denudation on . ° © . E E o e . 12
relations of—with rhyolites > . . . . c 4 24, 56, бі
intrusive іп rhyolites : 5 . E . E ° . 62, 63, 71
in contact with marble . 5 : e 5 5 o С « 718
altering schists > B "9g . . . = è ә . 18
foliated at contact with schists . ° . . 5 5 72
of Erinpura . . . . . 2 ° . 5 . 18, 73
of Jalor . . . E E D ° ° . ” 5 24, 71
of Siwana . S 5 . ° * . . 6 2 :245 64
at Каѕѕіаа . . . 5 . 2 . e с E 53
atSalawas . . : о 5 o ` . А С Ja 53
at Khairla b . e с Б o 5 4 . 2 5 155
at Deora o 5 5 . : . А 2 o e 56
Indrana range О о . o ° . E S d ل‎
Saora range . . . 3 ° ° . б o ` , ou
near Kundal . S 5 . S . : ° о 5 - 66
on Sukri river . o . . B o . : S . 68
at Chondrai . б : a . 5 о o ` С 224768
at Каопа . . S 5 . о . Я = а . 69
near Bhadrajun . 9 . : > . о ° . ° 70
at Dandali . - o . ° . : О а . 274
ас Jesai . : . - . . . E e . : . 76
ас Radhana . 3 1 5 S o 2 - б > o D

weathering of о ۵ о s 2 o 0 С 2 : E

102 INDEX,

Granite— 2
inclusions of rhyolite іп . о
rhyolite doubtfully intrusive in .
petrology of . S . .

Granophyric structure in Sitame granite

Groundmass of rhyolites . ° .
inlets of—in quartz phenocrysts .
micropegmatitic structure of 6 .
microcrystalline o o . .

Gypsum о 5 А о .

H

Hacket, C.A., geology of Rajputana А
section near Міпіагі о . .
section at Sojat . . .

Heat, solar,as an agent of ане .
Hexagonal inclusions in quartz phenocrysts
Holland, T. H., description of dyke rocks
Hornblende—

in sand . . . . .
large crystals of—in veins core ee
in groundmass of rhyolites . .
phenocrysts of . , . .
in lenticles of flow-structure . .
in sphzrulites . . . .
іп Siwana granite . . .

developed at contact of granite and rhyolite

Hornblende granite—

of Deora : . . .

of Indrana . - . . +

of Saora range с . ° .

at Dandali . . А А .

at Jesai С . . А .

at Chotan 2 . > .

at Radhana . . : 5 2

intrusive in rhyolite : . .

petrologv of . . . .
Hornstone, included in rhyolite .

Iceworn striz at Pokaran -

.

PAGE,
D 71
4 70.
4 Oo)

go

E 82
- 79
SI
2 1594!
©. 43
. 5
be 1G)
.. 20
то
‚бо; 81
$901

o 25 48
. 56, 63, 65
9578

on 62

475 85
87

90
20-01
56

63

9 vcn
7+

76

77

Oe = HY
61, 63, 71
. go
07,
* 31

INDEX.

Inclusions—

in granite . . - B .

of rhyolite in granite о . .

of rhyolite in diorite . ° .

of hornstone in rhyolite . . . c

of schist in granite . .

in quartz phenocrysts . З .
Indrana, range near c С o =
Insolation, effects of . o 5 b о

J

Jaisalmir—

geology of 5 . : Я . .

Mesozoic and Tertiary strata of О
Jaisalmir limestones, Jurassic fossils іп ,
Jaisalmir group

fossils of . . . . - .
Jalor, hill at . . . E . e
Jalor granite . . . . : .

petrology of . c 5 o o .
Jasol, hill at . . o E ees

` Jesai, conglomerate in lava at

granite at . . : . .
Jhika, section at . o : . . E
Jodhpur—

Vindhyansat - . 2 . : .

buildingsof . 16% . . .
relations between Malanis and Vindhyans at
Jodhpur sandstones d 5 о 5 E

Kaimur sandstone, at Sojat ; 0 . .
Kalinjur hill, granite of , с е E ‹

102

PAGE.
54, £5, 69
65, 71, 76

2758

67

` 69

79» 81

EOS

10
7
O RA)
41535
5

о” «S

о

o ЭП

о 01

51
76
272576
64
28
220-29
27, 45
` E
20
o ER

104 INDEX.

Kanki, mica granite at e б D o
Kannai (Cutch) foraminifera in limestone of
Kaolin, felspar altered into . o
Kaonla, granite at . . . à
Kapuli, Fuller’s earth at . ^ :
Khairla, schists and Malanis at о 2
hills at. . o . 5 О
Khari, Vindhyan sandstones at : .
carbonate of limein sand at о .
Khatu (near Sojat), section at 5 Б
Khatu (Barmer desert), Malanis at c
Korna, Malanis at . . . ò
Kuchri, ammonite bed of P . :
equivalent to Abur group © .

“ Kuddi ”, local name for gypsum . .
Kuip, ridge north of . . .

hill near . . . . .
Kunkur, “glacis ” formed of . : .
origin of . . . . .
Kundal, mica granite at . > .
IL

Lapilli in tuffs с e

Lathi group © . . . .
plant remains іп : . . .
ageof . . . . .

Lavas, viscid character of . . .

Lawa, see Lowo.

Leaves, remains of—in Barmer sandstones

Lenticles in flow-structure ~ .

Lime іп sand ` 5 . 5

Limestone, boulders of—in Talchirs
Vindhyan 5 5 .

List of formations : 6 o «
іп Jaisalmir . . 5 . e

Liquid cavities in quartz . . .

Lowo, boulder bed of А .

Ludrara, granite at . р .

PAGE.
8 66
e 39
an $82
. 69
OS
2820
e 55
27 50
. 40
26

“4 75
• 47
33 5, 35
. 7
43

e 58
59

12

D 41
- 66
۰ 89
RSI
34

* 34
25022
4034
2. |85
39

. 31
. 26
* 4, 16
Ges
SE
5 31,44
o. (64

INDEX. 105

PAGE.
Luni river œ S © B 6 О . . D О © JI
old bed of—near Pachpadra . . . . . А c . 14
Lunu, section at `. o d % о о o © . 5 о a ZA

Lyd’s Hole, rhyolite from ` — . o . . > 5 б . 88

M
Madli, perlitic stucture in rhyolite at E e . E ° . e 49
Madpura, gypsum near > . 5 ò 5 . D . • 43
Magnetite —
in rhyolites : С e 75782185
rare in granite . . . © . . . . б . 9I
Malani rhyolites—
petrology of . о o 5 d c . о o ETS
compared with Wrekin rocks o С e . 2 . e 88
Malaniseries— . . 5 . o о . . . e » IQ
derivation of name . c . : С . о . . o 5
relations to Aravalli rocks o o с о ó © e А б
effects of denudation оп . е . . о . » . e 12
no representatives elsewhere , . E . . б o © I5
area covered by . . . 5 . . o c e 21
granite intrusive in ` о - . . ° 5 . , 24
relations to Vindhyans . : 5 . > . : а o BO
inliers near Bastua . . o . . E . . А:
at Jodhpur . . . o . c d o o 6 . 45
at Baorli ONE 5- EE ЕСТИ en 46
at Agolai С А . 6 . 2 o c б E 222847,
at Korna D о с . 5 : e 5 . б о 247)
at Nagona . Р . . . o - > . с DEE
at Thob % о . о 0 o o . . . 61 €0
near Patodi œ 5 . E o c o o o . 22 50
in Nagar range 5 . . . . . . SZ
near Rampura S 6 с d о б e % ° NDA!
at Phinch D . . . . D . D D D D 55
near Khairla , . ; . . . . б . . . 55
atSamdari . . . o ò D à c . 5 . 55
at Mongla . e Ó e E . 55
іп Siwana hills о о D А 3 o © SE
near Chanod S . : ó . . ‹ - 66

106

Malani series—
in Bhadrajun range
Roza hill о
at Khatu 5
west of Barmer

Makrana, marble quarries at

Malgarh, vertical flow-structure in Se at
Manpur, muscovite in granite at
Manual of Geology of India, 2nd Edition, xime

putana
Marble of SES
Makrana o

>

INDEX.

Masuria hill, GE and Sege at

Matrix of tuffs

McMahon, Col., ГООО, of Malani EIS

felsites of Tusham hill

Meli, hills near О

Mesozoic strata . C
Mica—
insand . о .
in tuff

not present in EE
in felsite of Tusham hill

in Jalor granite
Mica granite—

intrusive in rhyolites

petrology of .

at Rassida .

atSalawas . 5

at Kanki

at Kundal

on Sukri river
at Chondrai .
at Kaonla

near Bhadrajun
at Jalor

Microcrystalline ааа:
іп fragments in breccias

Microlites, of felspar in groundmass

of hornblende
Micropegmatite—

in groundmass

phenocrysts of

in Siwana granite

ә

© geology of W.

PAGE:
2 70
71.
15),
SEN
К,
. 68
D 91
Raj-
e. 8
9. $6)
2 “17
D 45
21180
7
88
- -56
34
38
. 89
2 78
5 095
2 DÉI
«68, 71
J Фу
53
53
- 460
e .. 66
68
.- 68
. 69
o TO
93371
84
e 89
. 92
„ 85
. 182
° 81
9o

INDEX. 107

PAGE.
Middlemiss, C. S., boulder bed of Salt Range : : : . 32,87, 90
Minerals of Aravalli region E . . . o . . : 6
Miniari, section near. Р à 5 : . ues о 109, 67
Mongla, Malanis at 6 o 5 5 Я 5 i 2 5 e 55
Mosaic іп groundmass . . . D . . 5 2 o . 83
* Multani Mitti” . о . 3 5 > 0 с б А o SEI
Muscovite іп Jalor granite . . . о . А 5 o 6 01

N
Nagar range . . С . Я 3^ ^ wo . А . 14/0/52
Nagona, Malanis at a b c о 0 e ` . 5 217749
possible fissure vent at . : . о . c . . с 48
perlitic structure in rhyolite near . . . . = d 22886
Nausar, Barmer sandstone near . o D 5 ° . c 21502574:
Nepheline . . =e tie - : . . . 5 5 200892
Nodular rhyolite . C c х : С . о . : .67, 70
Nosean c . . . o =ò с o . . . 30:92
Nummulitic limestone . . а . , . " : . » 5
of Jaisalmir . : : : š . : c . о Asa
о
Oldham, В. D., geology of Jaisalmir о 5 о 6 5 b . 6,34
rock sculpturing by wind . : О 5 . . B то
relation of Jodhpur Vindhyans to main area o . . . 2120
boulder beds at Bap " . .. . 5 c : : А ІЗІ
Oligoclase, phenocryst of . : d 6 я . ` ó 85
Olivine dolerites . О o о S с . . * 51, 53, 91
Organic remains, doubtful in Vindhyans 5 4 н 5 А . 80
іп Barmer sandstones . . 2 О o > . A - 33
Origin of kunkur . . . o > . 5 . o ` 22 771
of Salt, - С С 5 с О С О . . o 3 Яй
of gypsum . . ° o 5 2 P > д Қ Б
of quartz mosaic in groundmass В 5 o 5 5 3 5. 55

Orthoclase in groundmass , : - E > E 8 А 5 5

108 INDEX.

S PAGE
Osia, doubtful fossils in Vindhyans of . S 5 E о о О 220)
Vindhyans at С o . c c o о о о . 44

P

Pachpadra, salt deposits of . : S : 5 E E T 14,41
Parihar group A s - 5 Š о E o D © o. 85

Pati, hillat . с . . . o с ‹ . E ғ .7 бо
Patodi, Malanis near. 5 : о 5 В ó B. 69
Pebble beds, in Vindhyan SSC Ша Я A о o о «N23
of Amir . o , . . . . 35
interstratified with айх o ^ o 5 . Es e 62, бо, 76

іп Barmer sandstones E . . . . : . c “33,74
Pegmatite in granite veins é 5 o . c o о ; Ox. dao
Perlitic structure in rhyolites c . o : А . o -49, 86
Phenocrysts, quartz 5 о E c . e ` . o 22970
secondary growth of - о с . . : ; 5 e Зо
inclusions іп . . . : . : . . . 5 e 8E
felspar . . . . o . А . : c 6 ev ВІ
hornblende’. . . S А . 5 c . . - 2
Phillips, J. Arthur, inclusions in granite о . e o о « B4
Phinch, Malanis at c . с 5 . . > С a 5
Phulan, granite at . > . o 2 . с . . 2 OR
Physical features . . о . о . с . S . SNO
Plagioclase in groundmass . . E . . . . . 3 83
in Jalor granite . . Я z . . ` . 27 І
Plant remains, in Barmer Seen . e E А . 5 :85533
in Lathi group Я . 5 ac б э scs en
Plateau sandstones west of Jodhpur . . . . . . . 45
Pokaran, boulder bed of . . . 2 5 ; . с aen
basalt associated with 5 C о > . 2 : 525
Pokaran, Vindhyans at . . . 2 3 . . В D o
Pseudo conglomerate at Jodhpur . . . К 5 2 ; 127,46
Pulviaulina іп sand 5 . . e . . . 5 s o ZO
“ Punna sandstones” . . o . o : 5 2 F e 3
Pyromeride of Wuenheim . . o : à " ^ A 56

Quartz, іп sand . . . . 5 о o D ó or af
in groundmass of rhyolites - z . С 0 P З .78,82

* Quartz mosaic” . . Ue сы

in fragments in breccias . : -
Quartz phenocrysts . . . .
secondary growth of © О .
inclusions іп . А o 2 .
Quartzite, distribution of e - с
аі Ѕапӣегао . - 5 ° o
R
Radhana, granite at . . c .
Rain prints in shales . А ° .
Raki, Malanis near б Я Ж
Rajpura— 5
relations of schists and Malanis near
Malanis near . : . . .
Rassida, granite at о d 5 ;
Recent deposits . С : - с
Rhyolites -=
description of . . . .
petrology of . . . : o
specific gravity of . o 5 .
colours of . . 5 2
fissile, at Nagona . . О .
sphzerulitic . .
perlitic . А . 6 . c
altered . . . . .
nodular . = . à с D
granite intrusive in . . . .
included in granite . . . .
included in dolerite b . .
intrusive in lava flows
intrusive in granite . б .

in boulder bed of Salt Range . .

compared with Wrekin rhyolite
Rivers . . с а -
Rock sculpturing by wind . . А
Rosenbusch, pyromeride of Wuenheim .
Roialiainsand . . 5 c .
Roza hill, granite of S 5 2 С

56, 61, 62, 63,

109
PAGE,
б 83
89
79
. Bo
o n
- 16
72
vi 77
= 46
D 61
20
54
e 53
37
20
o 78
> 79
. 79
- 48
49, 66
. 49
«1163.
:67, 70
68, 71
«65; 71
2 5
58. 59
2870
б 87
o 89;
13
a 10
. 86
* 40

IIO INDEX.

PAGE.
S
Sakarna, rhyolite included in granite at . а . . о S e 7E
Salawas, granite at . о o S : o . 5 V DES
Salt, origin of o . 5 o 5 = à ` GE AE AG
Salt Range, boulder bed of . . . . 5 . о o 32, 87
volcanic ash in б А . . . c . 8 o . 90
granite іп . . о . o . o e А б ۰ OF
Sambhar lake, salt of . о ot 6 : 5 : . 6 27 42
Samdari, Malanisat œ o ° . 2 o б 5 2 5, G8
Sand, blown . ò . В > : . . o . . On Sy
size of grain . © . . . . - о . : 22729
composition of : . . : o . 5 . a 15838
of local origin c o о . o . о ° . 2477309
carbonate of lime in . 5 о : о 2 о с 7 507
foraminifera in . с © : 5 d 5 . e 22729
derived from Cutch. . . e . ; . о 4 2112830
angular condition of grains of . . . . с о . . 40
red—derived from Vindhyan sandstones . . . 5 . 2 40
Sanderao, section at . . : . 5 o o А c 2872
Sandhills—
attributed to action of earthquakes . . - SE . . 4
Мг. Blanfordon . . . . 2 $ . o . 5 5
intermediate type of e . : 5 : . . : IG
іп Barmer desert . : . . 5 - . 5 ; КЗ
height of . . . o А . 5 А . 5 41212
distribution of . . А > 3 С 3 5 5 . on. BY
Sandstones, effects of denudation on : o о . . e QNSE
Vindhyan S . : ‘ ` d . E . о 2 126
Barmer . . . c . : 5 : . А . +33) 74
Sanidine ` Р с . . o e 82,02
Sanpa, Barmer sandstone at . . . 2 . . . . a. WS
Saora range . ^ i Я 2 5 5 5 А А o - 64
Saparo, Malanis at . . А 5 . . . > S gom
Sarangwa, marble at . 5 с А 2 S : д А 7
Sarnu, Barmer sandstone at . 5 о 5 5 c . А 5 n3
Schillerisation of felspar З 5 б : : о o 82
Schists—
distribution of . 5 2 - о S 5 5 : реб
calcareous . . . > . . . . . > ОО,

Erinpura granite intrusive їп, 5 A 2 : . 5 eS

INDEX.

Schists—
included in granite . o > .
at Khairla . О : . v
near Bhaonagar . . o .
north of Erinpura • 6 . S

Sea, former extension of—into Luni valley
Secondary growth of quartz phenocrysts .

devitrification 5 ó . .
Sedimentary rocks . . > >
Selo, mica granite near . . E .

Shales at base of Vindhyans . D А
Shingle beds of Amir & . e E

Siner, section of hillat . о о О
Sirohi, granite in . А . б
Siwana, hills near . T 0

Siwana granite . : о c o

petrology of . e . c :
Slaty schists at Miniari . S o А

atKhaira . . ° a
Sodalite 5 . : . о ә
Sojat, section at . С а . А
Sondri, Вагтег sandstone at . А d
Specific gravity—

of rhyolites . . . ó 5

of dyke rocks . о ` .
Sphzrulitic structure in rhyolites . .
Stratigraphical features—

crystalline rocks . . : .

sedimentary rocks . © . o

Striated pavement near Pokaran . о
Striated twinning in felspar phenocrysts .

Structure, flow c 5 ; О 5
perlitic . 5 C 5 . .
sphzrulitic . e . . .
fibrous—in devitrified glass . e
granophyric—in Siwana granite .

Sub-recent conglomerates o - с

Sukri river, mica graniteon . z 5

Sun’s heat as an agent of denudation .

Sursagar, conglomerates at base of Vindhyans near

Til
PAGE,
. 69
. 55
. 68
4 73
.14,42
Bo, 84
o БЕ
21:126
- 66
27945
* Б
«62
1118
.57, бо
EE
. 90
Eet o
% 55
D 92
4 26
4 74!
. 79
22 02
49, 66, 86
e 15
2206 20
о 31
2. 82
2195
оз 90
H 86
. go
00
II, 14, 36
a
D 10

e 45

LIZ INDEX.

T
PAGE.
Talchirs, in eastern Jaisalmir . . o О . > Е S I
basalt associated with С . : . . o 5 5195
of Bap апа Pokaran . . e . . . : * 3!
containing boulders of limestone . e . E З о 3 G1
relations to Vindhyans œ . - . B А . . $c qu
Talus 5 . о e . О 5 . e . 5 550319
distributed by sand . . à. Я : RE e
Taratra, granite at . S o D o EE
Tarwa, Malanis at © . 5 . VUE
Teori, sand at о o е - d 5 .39,40
Tertiary strata . : с . E . . . . 2240
Tesingri, Malanis at ; с c о t . 5 . ۰ 49
Thob, Malanis at . . . . ` . . . . 59
Тіпсиайе . > 5 e . . . . 75» 03
Tufa, calcareous . с 5 . . о 5 o . .12, 41
Tuffs—
interstratified with lavas . . С 5 3 . 21,23
mica in ^ З S c О о.
colour of С о - - © 5 . o р 5 $1579
specific gravity of . 5 В 5 А . : d 5 225870
petrology of . 2 5 А . 5 . 5 З 89
ає Когпа . e 5 А c С 5 . 5 . о ДЭ
near Patodi . . 5 2 С 2 . % D 50
in Nagar range 5 ; е с o О 5 © . 3 52
in ridge north of Kuip . . . . 5 . 5 58
at Siwana o А D . с 5 : 5 бо
altered, near Golia 3 о 5 : . : . . OS
sandy, at Pati И . . . . . - 69
Tusham hill, felsites of . ^ 5 а 22, 88
Twinning of felspar phenocrysts e 5 . 81
U
Unconformability—
between schists and Malanis > қ А у : то
between schists апа Vindhyans . . j . . e : 206

between Vindhyans and Malanis

INDEX,

Unconformability—

between Malanis and Barmer sandstones .

between Talchirs and Jurassics
between Talchirs and Malanis
Unio, in Barmer sandstones , 5 5

Vents—
probably of fissuretype . о .
perhaps marked by granite bosses

conjectured—at Nagona . о .
Vertical flow-structure in rhyolites , .
Vesicular, rhyolite. о : o .

structure in groundmass , А .
Vindhyan limestone—

at Sojat. О . .

boulders of—in Talchirs e Bap
Vindhyan sandstones . 2 ` o

relations of—to Talchirs . . .

description of . . e . .

capabilities as building stone . .

relations of—to main area 5

area covered by 5 . .

doubtful fossils in . . . 5

west of Jodhpur. . .
Viscid character of lavas 5

Volcanoes, subaerial
Volcanic ash in boulder bed di Salt Renee
Volcanic cene, conjectural, near Nagona

W
Walther, Dr. J., * Denudation in der Wüste ”.
Wells—
salt water in . : . . .
gypsum used forlining . : ү
Wind as an a;ent of denudation . С

‹

48,

448,
47, 58,

22
25
SE
68
67
78

26
32
26
28
28
28
29
29
30
44
23
21
go
51

IO

42
43
10

114

Wood, fossil, in Lathi group
Wrekin, rhyolites of
Wuenheim, pyromeride of

* Zeugen," west of Jodhpur

Zirkel, hexagonal inclusions in quartz sansa

_ INDEX.

2

Zones, corrosion of quartz phenocrysts in

in felspar phenocrysts

45
80

79
82

LIST OF ILLUSTRATIONS. II5

LIST OF ILLUSTRATIONS.

PLATE I.
Fig. 1. Surface of Malani rhyolite, grooved and polished by action of wind.
Бір. 2. Granite block undercut by wind. Near Chotila.
Fig. 3. Sub-recent conglomerate. Bed of Sukri river near Darri.
Fig. 4. Diagram section across valley south-west of Miniari.

PLATE II,

Fig. 1. Junction of Malani beds (a, a) and Vindhyau sandstones (b, b), showing
rounded blocks of Malanis (c, c) imbedded in silt (d, d), forming a
pseudo-conglomerate north-east side of scarped hill south-west of
Sursagar, Jodhpur.

Fig. 2. Scarped outliers (Zeugen) of sandstone near Ghoriala, Marwar.

PLATE III,
Fig. т. Hill (1,634 ft.) west-south-west of Kuip, from the north.
Fig. 2. Junction of Malani rhyolite and granite. Hill west of Indrana, from

the south.

PLATE IV.
Fig. r. Section of hill at Siner. r, Fuidal rhyolite. 2, Porphyritic rhyolite,
3, Dark greenish basic rock with amygdales. 4, Conglomerate.
5, Vesicular rhyolite. 6, Porphyritic rhyolite. 7, Dyke dolerite.
Fig. 2. Contorted granite veins in schist. Hill west of Pomao, neer Erinpura.
Fig. 3. Veins of granite (a, a) penetrating rhyolite (b, b). South end of range
west of Indrana.

Fig. 4. Vein of granite (a, a) intrusive in rhyolite (b, b). Ravine south of Golia,
Saora range.
PLATE V.

Fig. 1. Chasm formed by weathering out of intrusive dyke in rhyolites. Hill
side south of Nagar.
Fig. 2. Nodular rhyolite near Bakhal. Bhadrajun range.

PLATE VI.
Granite hill at Kaonla.

PLATE VII.

Granite at Kaonla.

116

LIST OF ILLUSTRATIONS.

PLATE VIII.

Hills of granite near Erinpura Road Station, Rajputana-Malwa Railway.

Fig.
Fig.
Fig.
Бір.
Fig.

Fig.

Fig.

Fig.
Fig.
Fig.

Fig.
Fig.

Fig

Fig.

Fig.
Fig.

Fig.

Fig.

PLATE IX.

I. Quartz phenocryst corroded by Magma. Ordinary light.
2. Quartz phenocryst corroded along Zonal lines. Ordinary light.

. Phenocryst of quartz, partially remelted and drawn out along lines

of flow. Ordinary light.

. Quartz phenocryst surrounded by irregular “court” of secondary

quartz. Nicols crossed.

. Quartz phenocryst surrounded by concentric “court”? of secondary

quartz. Nicols crossed.

. “Court " surrounding quartz grain, showing details of secondary

growth, Nicols crossed.

BEATE XK

. Felspar phenocryst formed of interpenetrating individuals. Nicols

crossed.

. Micropegmatitic phenocryst of quartz and felspar. Ordinary light.
. Flow-stucture. Ordinary light.

. The same, more highly magnified, showing sphzrulitic arrangement

of hornblende needles. Ordinary light.

. Flow and perlitic structures. Ordinary light.
‚ Perlitic structure. Ordinary light.

PLATE XI.

. Perlitic structure. Ordinary light.

The same, more highly magnified, showing minute sphzerulites,
Ordinary light. ;
Sphærulitic structure. Ordinary light.

. Breccia formed of glass chips imbedded in lava, showing devitrified

condition of fragments. Ordinary light.

. One of the fragments in Fig. 4. More highly magnified, showing

details of devitrified structure. Ordinary light.

. Contact between granite and rhyolite, showing development of

hornblende at junction, Ordinary light.

е?

GEOLOGICAL SURVEY OF INDIA
RK Ds Ka Louche

Memoirs Vol. XXXV, Pt. 1, PLI

Surtace of Malani Rhyolite,
grooved & polished by action of wind

Granite block undercut by wind. Near Chotila.
Fig 1.

Fig 2.

Sub-recent Conglomerate, Bed of Sukri R. near Darri

Fig 3:

Diagram Section across Valley 5. №. of Miniari

2
Fig 4. s

GEOLOGICAL SURVEY OF INDIA

T. D. La Touche Memoirs Vol. XXXV, Pt. 1, Pl. II

д = =N = See e
Junction of Malani beds (a,a) and Vindhyan Sandstones (b,b) Showing
rounded blocks of Malanis сус embedded in silt d,d, forming a pseudo-

conglomerate. N. E. side of scarped hill S. W. of Sur Sagar, Jodhpur.

Fig т.

E Е
Delta, e

SCARPED OUTLIERS (ZEUGEN) OF SANDSTONE NEAR GHORIALA, MARWAR.

Fig 2.

GEOLOGICAL SURVEY OF INDIA

T. D. La Touche Memoirs Vol. XXXV, Pt. 1, PLIII

a

jJ

IIT

І
1

4 CINE

HILL (1634 ft.) W. S. W. FROM KUIP, FROM THE NORTH

Гір г.

ЕНЕГЕ ИКЕ ЫСТЫ 22275222

Rhyolite

м

"v? Line of Junctio
m RS
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INDRANA, FROM 5.

Fig 2.

GEOLOGICAL SURVEY OF INDIA

T. D. La Touche Memoirs Vol. XXXV, Pt. 1, РІ. IV

| Dolerite
e.

SECTION OF HILL AT SINER.

2. Porphyritic rhyolite.
ith amygdales
s. Vesicular rhyolite.

т. Fluidal rhyolite.

3. Dark greenish basic rock w
4. Conglomerate.

6. Porphyritic rhyolite. Contorted Granite Veins in Schist

7. Dyke Dolerite. Hill W. of Pomao. near Erinpura.

Fig 2.

Veins of Granite (a,a) penetrating Rhyolite (b,b) S. end of range W. of Indrana.

Fig 3.

7

Vein of Granite (a,a) intrusive in Rhyolite (b,b) Ravine S. ot Golia, Saora Range.

Fig 4-

bL
GIE
ee SE

у

E
да AA e
oe Eu

RT

GEOLOGICAL SURVEY OF INDIA

T. D. La Touche Memoirs Vol. XXXV, Pt 1, Pl. V

CHASM FORMED BY WEATHERING OUT OF INTRUSIVE
DYKE IN RHYOLITES. HILL SIDE S. OF NAGAR,

Fig 1.

NODULAR RHYOLITE NEAR BAKHAL, BHADRAJUN RANGE.

Fig 2.

KOLOGICAL SURVEY OF INDIA

G

XXXV, Pt. 1, PL VI

Memoirs Vol.

Touche.

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GRANITE HILL AT KAONLA.

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ШАЛА 7 74 “АХХХ Тол SOWN NOT YT AL

VIMNI HO ATANNS 72792070749

GEOLOGIC AT SURVEY ОЕ INDIA.

T D. La Touche: Memoirs. XXXV. BE РІ:

BFMROSE & SONS, LIMITED, DERBY, LONDON & WATFORD.

GEOLOGICAL SURVEY OF INDIA.

T. D. La Touche. Memoirs. “Vols XXXV ИРЕ т. РІ то;

BEMROSE & SONS, LIMITED, DERBY, LONDON & WATFORD

GEOLOGICAL SURVEY OF INDIA.

T. D. La Touche. Memoirs. Vol. XXXV. Part І. Plate 11.

Memoirs, Vol. XX XV, Pt. 1.

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Reg. No. 390, Geol. Sur.—Dec; 01.—590.

Part 3.—Note on the progress of the gold industry in Wynaad, Nilgiri district. Notes on
the representatives of the Upper Gondwana series in Trichinopoly and Nellore-Kistna
` districts. Senarmontite from Sarawak.

Part 4.—On the geographical distribution of fossil organisms in India. Submerged forest
on Bombay Island. 4

Vot. XII, 1870.

Part r.—Annual report for 1878. Geology of Kashmir (third notice). Further notices of
Siwalik mammalia. Notes on some Siwalik birds. Notes of a tour through Hangrang
and Spiti.. Ona recent mud eruption in'Ramri Island (Arakan). On Braunite, with
Rhodonite, from near Nagpur, Central Provinces. Palzontological notes from the
Satpura coal-basin. Statistics of coal importations into India.

Part 2—On the Mohpani coal-field. On Pyrolusite with Psilomelane occurring at Gosalpur,
Jabalpur district. A geological reconnaissance from the Indus at Kushalgarh to the
Kurram at Thalon the Afghan frontier. Further notes on the geology of the Upper
Punjab.

Part 3.—On the geological features of the northern part of Madura district, the Pudukota
State, and the southern parts of the Tanjore and Trichinopoly districts included within
the limits of sheet 80 of the Indian Atlas. Rough notes on the cretaceous fossils from.
Trichinopoly district, collected in 1877-78. Notes on the genus Sphenophyllum and
other Equisetacez, with reference to the Indian form Trizygia Speciosa, Royle (Sphe-
nophyllum Trizygia, Ung.). Оп Mysorin and Atacamite from the Nellore district. On
eo adam from the.Khasi Hills. On the Joga neighbourhood and old mines on the Ner-
udda. ·

Part 4.—On the 'Attock Slates’ and their probable geological position. On a marginal
bone of an undescribed tortoise, from the Upper Siwaliks, near Nila, in the Potwar, Pun-
jab. Sketch of the geology of North Arcot district. On the continuation of the road
section from Murree to Abbottabad.

Vor. XIII, 1880.

Part r.—Annual report for 1879. Additional notes on the geology of the Upper Godavari
basin in the neighbourhood of Sironcha. Geology of Ladak and neighbouring districts,
being fourth notice of geology of Kashmir and neighbouring territories. Teeth of fossil
fishes from Ramri Island and the Punjab. Note on the fossil genera NOggerathia, Stbe.,
NOggerathiopsis, Fstm., and Rhiptozamites, Schmalh., in palzeozoic and secondary rocks
of Europe, Asia, and Australia. Notes on fossil plants from Kattywar, Shekh Budin, and
Sirgujah. On volcanic foci of eruption in the Konkan.

Part 2.—Geological notes. Palzontological notes on the lower triasof the Himalayas. On
the artesian wells at Pondicherry, and the possibility of finding such sources of water-
supply at Madras. |

Part 3.—The Kumaun lakes. On the discovery of а celt of paleolithic type in the Punjab.
Palzontological notes from the Karharbari and South Rewah coal-fields. Further notes on
the correlation of the Gondwana flora with other floras. Additional note on the artesian
wells at Pondicherry. Salt in Rajputana. Record of gas and mud eruptions on the
Arakan coast on 12th March 1879 and in June 1843. ?

Part 4.—On some pleistocene deposits of the Northern Punjab, and the evidence they afford
of an extreme climate during a portion of that period. Useful minerals of the Arvali
region. Further notes on the correlation of the Gondwana flora with that of the Aus-
tralian coal-bearing system. Note on reh or alkali soils and saline well waters. The reh
soils of Upper India. Note on the Naini Tal landslip, 18th September 1880.

Vor. XIV, 1881.

Part r.—Annual report for 1880. Geology of part of Dardistan, Baltistan, and neighbouring
districts, being fifth notice of the geology of Kashmir and'neighbouring territories. Note
on some Siwalik carnivora. The Siwalik group of the Sub-Himalayan region. On the
South Rewah Gondwana basin. On theferruginous beds associated with the basaltic
rocks of north-eastern Ulster, in relation to Indian laterite. On some Rajmahal plants.
Travelled blocks of the Punjab. Appendix to ‘Paleontological notes on the lower trias
of the Himalayas.’ On some mammalian fossils from Perim Island, in the collection of the
Bombay Branch of the Royal Asiatic Society.

H

Part 2.—The Nahan-Siwallk unconformity in the North-western Himalaya. On some Gond-
wana vertebrates. On the ossiferous beds of Hundes in Tibet. Notes on mining records, |
and: the mining record office of Great Britain ; and the Coal and Metalliferous Mines |
Acts of 1872 (England). On cobaltite and danaite from the Khetri mines, Rajputana ;
with some remarks on Jaipurite (Syepoorite). On the occurrence of zinc ore (Smithsonite
and Blende) with barytes, in the Karnul district, Madras. Notice of a mud eruption in the
island of Cheduba. 5 :

Part 3.—Artesian borings in India. On oligoclase granite at Wangtu on the Sutlej, North- |
west Himalayas. On ‘а fish-palate from the Siwaliks. Paleontological notes from the
Hazaribagh апа Lohardagga districts. Undescribed fossil carnivora from the Siwalik hills
in the collection of the British Museum. s Ж

Part 4.—Remarks on the unification of geological nomenclature and cartography. Оп the
geology of the Arvali region, central and eastern. Оп а specimen of native antimony |
obtained at Pulo Obin, nearSingapore. On Turgite from the neighbourhood of Juggia-
pett, Kistnah district, and on zinc carbonate from Karnul, Madras. Note on the section

from Dalhousie to Pangi, vid the Sach Pass. On the South Rewah Gondwana basin,
Submerged forest‘on Bombay Island. : : қ

Vor. ХУ, 1882.

Part 1.—Annual report for 1881. Geology of North-west Kashmir and Khagan (being. sixth
notice of geology of Kashmir and neighbouring territories). Оп some Gondwana laby-
rinthodonts; On some Siwalik and Jamna mammals. The geology of Dalhousie, North-west
Himalaya. On remains of palm leaves from the (tertiary) Murree and Kasauli beds in
India. On Iridosmine from the Noa-Dibing river, Upper Assam, and on Platinum. from
Chutia Nagpur. On (1) a copper mine lately opened near Yongri hill, in the Darjiling
district; (2) arsenical pyrites in the same neighbourhood; (3) kaolin at Darjiling (being
3rd appendix to a report on the geology and mineral resources of the Darjiling district
and the Western Duars). Analyses of coal and fire-clay from the Makum coal-field, Upper
Assam. Experiments on the coal of Pind Dadun Khan, Salt-range, with reference to
the production of gas, made April 20th, 1881. Report on the proceedings and result of

_ the Internationa! Geological Congress of Bologna. e

Part 2.—General sketch of the geology of the Travancore State. The Warkilli beds and
reported associated deposits at Quilon, in Travancore. Note on some Siwalik and Nar-
bada fossils. On the Coal-bearing rocks of the valleys of the Upper Rer and the Mand
tivers in Western Chutia Nagpur. On the Pench river coal-field in Chhindwara district,
Central Provinces. On borings for coal at Engsein, British Burma. On sapphires re-
cently discovered in the North-west Himalaya. Notice of a recent eruption from one of
the mud volcanoes in Cheduba. ;

Part 3.—Note on the coal of Mach (Much) in the Bolan Pass, and of Sharag or Sharigh
on the Harnai route between Sibi and Quetta. New faces observed on crystals of. stilbite
from the Western Ghats, Bombay. On the traps of Darang and Mandi in the North-
western Himalayas. Further note on the connexion between the Hazara and the Kashmir
series. On the Umaria coal-field (South Rewah Gondwana basin). Тһе Daranggiri coal-
field, Garo Hills, Assam. On the outcrops of coal in the Myanoung division of the
Henzada district.

Part 4.—On à traverse across some gold-fields of Mysore: Record of borings for’ coal at
Beddadanol, Godavari district, in 1874. Note on the supposed occurrence of coal on the
Kistna.

Vor. XVI, 1883.

Pari 1.—Annual report for 1882. On the genus Richthofenia, Kays (Anomia Lawrenciana,
Koninck) On the geology of South Travancore. On the geology of Chamba. On the
basalts of Bombay. d

Part 2.—Synopsis of the fossil vertebrata of India. On the Bijori Labyrinthodont. Ола
skull of Hippotherium antilopinum. On the iron ores, and subsidiary materials for- the
manufacture of iron, in the. north-eastern part of the Jabalpur district. On laterite and
other manganese ore occurring at Gosulpore, Jabalpur district. Further notes on ће
Umaria ccal-field. А

Part 3.—On the microscopic structure of some Dalhousie rocks. On the lavas of Aden.
On the probable occurrence of Siwalik strata in China and Japan. On the occurrence of
Mastodon angustidens in India. Ona traverse between Almora and Mussooree made in
October 1882. On the cretaceous coal-measures at. Borsora, in the Khasia Hills, near
Laour, in Sylhet.

Part 4—Palzontological notes from the Daltonganj and Hutar coal-fields in Chota Nagpur.
On the altered basalts of the Dalhousie region in the North-western Himalayas. On
the microscopic structure of some Sub-Himalayan rocks of tertiary age. On the geology
of Jaunsar and the Lower Himalayas. Оп a traverse through the Eastern . Khasia,
Jaintia, and North Cachar Hills. On native lead from Maulmain and chromite from. the
Andaman Islands. Notice of a fiery eruption from one of the mud volcanoes of Cheduba
Ee Arakan. Notice.—lrrigation from wells in the North-Western Provinces and

udh.

Vor. XVII, 1884.

Part i.—Annual report for 1883. Considerations on the smooth-water anchorages or mud
banks of Narrakaland Alleppy on the Travancore coast. ` Rough notes on Billa Surgam
and other caves in the Kurnool district. On the geology of the Chuari and Sihunta
parganas of Chamba. On the occurrence of the genus Lyttonia, Waagen, in the Kuling

- series of Kashmir.

Part 2.—Notes on the earthquake of 31st December 1881. On the. microscopic structure of
some Himalayan granites and gneissose granites. Report on the Choi coal exploration.
On the re-discovery of certain localities for fossils in the Siwalik beds. On some of the
mineral resources of the Andaman Islands in the neighbourhood of Port Blair. The
intertrappean beds in the Deccan and the Laramie group in western North America. i

Part 3.—On the miscroscopic structure of some Arvali rocks. Section along the Indus from
the Peshawar Valley to the Salt-range. On the selection of sites for borings in the
Raigarh-Hingir coal-field (first notice). Note on lignite near Raipore, Central Provinces.
The Turquoise mines of Nishàpür, Khorassan. Notice of a further fiery eruption from
the Minbyin mud volcano of Cheduba Island, Arakan. Report on the Langrin. coal!-field,
south-west Khasia Hills. Additional notes on the Umaria coal-field.

Part 4—On the Geology of part of the Gangasulan pargana of British Garhwal. On
fragments of slates and schists imbedded in.the gneissose granite and granite of the
North-west Himalayas. On the geology of the Takht-i-Suleiman. On the smooth-water
anchorages of the Travancore coast. On auriferous sands of the Subansiri river, Pon-
dicherry lignite, and phosphatic rocks at Musuri.. Work at the Billa Surgam caves.

Vor. XVIII, 1885.

Part r—Annual report for 1884. On the country between the Singareni coal-field and the
Kistna river. - Geological sketch of the country between the Singareni coal-field and
Hyderabad. On coal and limestone in the Doigrung river, near Golaghat, Assam.
Homotaxis, as illustrated from Indian formations. Afghan field notes. ;

Part 2.—A fossiliferous series in the Lower Himalaya, Garhwal. Оп the probable age of
the Mandhali series in the Lower Himalaya. On a second species of Siwalik camel (Camelus
Antiquus, nobis ex Fale. and Caut. MS.) On the Geology of Chamba. On the pro-
bability of obtaining water by means of artesian wells in the plains of Upper India.
Further considerations upon artesian sources in the plains of Upper India. On the

.geology of the Aka Hills. Onthe alleged tendency of the Arakan mud volcanoes to
burst into eruption most frequently during the rains. Analyses of phosphatic nodules and
rock from Mussooree. : ў

Part 3—On the Geology of the Andaman Islands. Оп a third species of Merycopotamus.
Some observations on percolation as affected by current. Notice of the Pirthalla and the
Chandpur meteorites. Report on the oil-wells and coal in the Thayetmyo district, British.
Burma. On some antimony deposits іп the Maulmain district. On the Kashmir earthquake
of 30th May 1885. On the Bengal earthquake of 14th July 1885. | :

Part 4.—Geological work in the Chhattisgarh division of the Central Provinces. On the Bengal
earthquake of July 14th, 1885. Оп the Kashmir earthquake of 3oth May 1885. Оп the
results of Mr. Н. B. Foote's further excavations in the Billa Surgam caves. Оп the
mineral hitherto known as Nepaulite. Notice of the Sabetmahet meteorite.

Vor. XIX, 1886.

Part 1.—Annual report for 1885. On the International Geological Congress of Berlin. On
some Paleozoic Fossils recently collected by Dr. Н. Warth, in the Olive group of the
Saltrange. Оп the correlation of the Indian and Australian coal-bearing beds. Afghan
and Persian Field notes. On the section. from Simla to Wangtu, and on the pterologi-
cal character of the Amphibolites and Quartz Diorites of the Sutlej valley.

Part 2.—On the Geology of parts of Bellary and Anantapur districts. Geology of the Upper
Dehing basin in the Singpho Hills. On the microscopic characters of some eruptive
rocks trom the Central Himalayas. Preliminary note on the Mammalia of the Karnul
Caves. Memorandum on the prospects of finding coal in Western Rajputana. Note on
the Olive Group of the Salt-range. Оп the discussion regarding the boulder-beds of the
Salt-range. On the Gondwana Homotaxis.: i

Part 3.—Geological sketch of the Vizagapatam district, Madras. Preliminary note on the
geology of Northern Jesalmer. On the microscopic structure of some specimens of the
Malani rocks of the Arvali region. On the Malanjkhandi copper-ore in the Balaghat
district, C. P.

Part 4.—On the occurrence of petroleum in India. On the petroleum exploration at Khátan.
Boring exploration in the Chhattisgarh coal-fields. Field-notes from Afghanishtan: No. 3,
Turkistan. Notice of a fiery eruption from one of the mud volcanoes of Cheduba Island,
Arakan. Notice of the Nammianthal aerolite. Analysis of gold dust from the Meza
valley, Upper Burma. :

Vor. XX, 1887.

Part r.—Annual report for 1886. Field-notes from Afghanistan: No. 4, from Turkistan to
India. Physical geology of West British Garhwal; with notes on a route traverse
through Jaunsar-Bawar and Tiri-Garhwal. On the geology of the Garo Hills. On some
Indian image-stones. On soundings recently taken off Barren Island and Narcondam.
On a character of the Talchir boulder-beds. Analysis of Phosphatic Nodules from the
Salt-range, Punjab. .

Part 2.—' he fossil vertebrata of India. On the Echinoidea of the cretaceous series of the
Lower Narbada Valley, with remarks upon their geological age. Field-notes: No. 5—to
accompany a geological sketch map of Afghanistan and North-eastern Khorassan. On the
microscopic structure of some specimens of the Rajmahal and Deccan traps. On the
Dolerite of the Chor. On the identity of the Olive series in the east with the speckled
sandstone in the west of the Salt-range in the Punjab.

Part 3.—The retirement of Mr. Medlicott. Notice of J. B Mushketoff's Geology of Russian
Turkistan. Crystalline and metamorphic rocks of the Lower Himalaya, Garhwal, and
Kumaun, Section I. Preliminary sketch of the geology of Simlaand Jutogh. Note on the
* Lalitpur' meteorite.

Part 4.—Note on some points in Himalayan geology. Crystalline and metamorphic rocks of
the Lower Himalaya, Garhwal, and Kumaun, Section II. The iron industry of the
western portion of the District of Raipur. Notes on Upper Burma. Boring exploration
in the Chhattisgarh coal-fields. (Second notice) Some remarks on Pressure ,Meta-
morphism, with reference to the foliation of the Himalayan Gneissose-Granite. A list and
index of papers on Himalayan Geology and Microscopic Petrology, published in the
preceding volumes of the records of the Geological Survey of India.

Vor. XXI, 1888.

Part r.—Annual report for 1887. Crystalline and metamorphic rocks of the Lower Himalaya,
Garhwal, and Kumaun, Section III. The Birds’-nest or Elephant Island, Mergui- Archi-
pelago. Memorandum on the results of an exploration of Jessalmer, with a view to the
discovery of coal. A facetted pebble from the boulder bed (‘speckled sandstone’) of
Mount Chel in the Salt-range inthe Punjab. Examination of nodular stones obtained
by trawling off Colombo.

Part 2.—Award of the Wollaston Gold Medal, Geological Society of London, 1888. The
Dharwar System, the chief auriferous rock series in South India. On the Igneous rocks
of the districts of Raipur and Balaghat, Central Provinces. On the Sangar Marg and
Mehowgale coal-fields, Kashmir.

Part 3.—The Manganese Iron and Manganese Ores of Jabalpur. ‘The Carboniferous
Glacial Period.’ The sequence and correlation of the pre-tertiary sedimentary forma-
tions of the Simla region of the Lower Himalayas.

Part 4.—On Indian fossil vertebrates. On the geology of the North-west Himalayas. On
blown-sand rock sculpture. Re-discovery of Nummulites in Zanskar. On some mica
traps from Barakar and Raniganj.

Vor. XXII, 1889, |

Part 1—Annual report for 1888. The Dharwar System, the chief auriferous rock-series in.
South India. (Second notice) On the Wajra Karur diamonds, and on M. Chaper's
alleged discovery of diamonds in pegmatite near that place. On the generic position
of the so-called Plesiosaurus Indicus. On flexible sandstone or Itacolumite, with special
reference to its nature and mode of occurrence in India, and the cause of its flexibility
On Siwalik and Narbada Chelonia. E

Part 2——Note on Indian Steatite. Distorted pebbles in the Siwalik conglomerate. ‘The
-Carboniferous Glacial Period.’ Notes on Dr. W. Waagen’s ‘Carboniferous Glacial
Period) On the oil-fields of Twingoung and Beme, Burma. The gypsum of the Nehal
Nadi, Kumaun. On some of the materials for pottery obtainable in the neighbourhood of
Jabalpur and of Umaria. бы г

Part 3—Abstract report on the coal outcrops in the Sharigh Valley, Baluchistan. Оп the `
discovery of Trilobites by Dr. Н. Warth in the Neobolus beds of the Salt-range. Geolo-
gical notes. On the Cherra Poonjee coal-field, in the Khasia Hills. On a Cobaltiferous
Matt from Nepal. The President of the Geological Society of London on the Interna-
tional Geological Congress of 1888. Tin-mining in Mergui district.

Part 4.—On the land-tortoises of the Siwaliks. On the pelvis of a ruminant from the
^ Siwaliks. . Recent assays from the Sambhar Salt-Lake in Rajputana. The Manganiferous
Iron and Manganese Ores of Jabalpur. On some Palagonite-bearing raps of the Ráj-
mahál hills and Deccan. On tin-smelting in the Malay Peninsula. Provisional index of
the local distribution of important minerals, miscellaneous minerals, gemstones, and quarry
stones in the Indian Empire. Part 1.

Vor. XXIII, 189o.

Part r.—Annual report for 1889. Оп the Lakadong coal-fields, Jaintia Hills. On the
Pectoral and pelvic girdles and skull of the Indian Dicynodonts. On certain vertebrate
remains from the Nagpur district (with description of a fish-skull). Crystalline and
metamorphic rocks of the Lower Himalayas, Garhwál and Kumaun, Section IV.. On the
bivalves of the Olive-group, Salt-range. On the mud-banks of the Travancore coast.

Part 2.—0On the most favourable sites for Petroleum explorations in the Harnaidistrict, Balu-
chistan. The Sapphire Mines of Kashmir. The supposed Matrix of the Diamond at
Wajra Karur, Madras. The Sonapet Gold-field. Field Notes from the Shan Hills, (Upper
Burma). A description of some new species of Syringosphæridæ, with remarks upon their
structures, &c. : j

Part 3.—On the Geology and Economic Resources of the Country adjoining the Sind-Pishin
Railway between Sharigh and Spintangi,and of the country between it and Khattan
(with a map). Report of a Journey through India in the winter of 1888-80, by Dr.
Johannes Walther, translated from the German, by R. Bruce Foote. On the Coal-fields of
Lairungao, Maosandram, and Mao-be-lar-kar, in the Khasi Hills (with 3 plans). Further
Note on Indian Steatite. Provisional Index of the Local Distribution: of Important
Minerals, Miscellaneous Minerals, Gem Stones, and Quarry Stones in the Indian Empire
(continued from p. 286, Vol. XXII). 78

Part 4—Geological sketch of Naini Tal; with some remarks on the natural conditions
governing mountain slopes (with a map and plate). Notes on some Fossil Indian Bird
Bones. The Darjiling Coal between the Lisu and the Ramthi rivers, explored during
season 1800-01 (with a map). Тһе Basic Eruptive Rocks of the Kadapah Area. The
Deep Boring at Lucknow. Preliminary Note on the Coal Seam of the Dore Ravine,
Hazara (with two plates). :

Vor. XXIV, 1801.

Part 1—Annual report for 1890. On the Geology of the Saltrange of the Punjab, with a
re-considered theory of the Origin and Age of the Salt-Marl (with five plates). On veins
of Graphite in decomposed Gneiss (Laterite) in Ceylon. Extracts from the Journal of а
trip to the Glaciers of the Kabru, Pandim, &c. The Salts of the Sambhar Lake in Rajpu-
tana, and of the Saline efflorescence called ‘Reh’ from Aligarh in the North-Western
Provinces. Analysis of Dolomite from the Salt-range, Punjab. . EECH

Part 2—Preliminary Report on the Oil locality near Moghal Kot, in the Sheráni country,
Suleiman Hills. On Minera! Oil from the Suleiman Hills. Note on the Geology of

the Lushai Hills. Report on the Coal-fields in the Northern Shan States. Note on

the reported Namséka Ruby-mine in the Mainglón State. Note on the Tourmaline
(Schorle) Mines in the Mainglón State. Note ona Salt-spring near Bawgyo, Thibaw
State. ;

Part 3.—Boring Exploration iz the Daltongunj Coal-field, Palamow (witha map). Death of
Dr. P. Martin Duncan. Contributions ¢o the study of the Pyroxenic varieties of Gneiss
and of the Scapolite-bearing Rocks. :

Part 4.—On a Collection of Mammalian Bones from Mongolia. Further note on the Darjilin
Coal Exploration. Notes on the Geology and Mineral Resources of Sikkim (with a
map). Chemical and Physical notes on rocks from the.Saltrange, Punjab (with two
plates).

Vor. XXV, 1892.

Part r—Annual report for 1801. Report oz the Geology of Thal Chotiáli and part of the
Mari country (with a map and 5 plates). Petrological Notes oz the Boulder-bed of the
Salt-range, Punjéb, Sub-recent and Recent Deposits of the valley plains of Quetta,
Pishin and the Dasht-i-Bedaolat; with appendices om the Chamans of Quetta; and the
Artesian water-supply of Quetta and Pishin (with one plate).

Part 2.—Geology of the Saféd Kóh (with 2 plates of sections). Report oz а Survey of the
Jherria Coal-field (with a map and section plates) (out vf print). ;

Fart 3.—Note оп the Locality of Indian Tscheffkinite. Geological Sketch of the country
north of Bhamo. Preliminary Report on the economic resources of the Amber and Jade
mines area iz Upper Burma. Preliminary Report oz the lron-Ores and lron-Industries
of the Salem District. “От the Occurrence of Riebeckite in India. Coal on the Great
Tenasserim River, Mergui District, Lower Burma.

Part 4.—Report оп the Oil Springs at Moghal Kot iz the Shirani Hills (with 2 plates),
Second Note oz Mineral Oil from the Suleiman Hills. Ox a New Fossil, Amber-like.
Resin occurring in Burma. Preliminary notice om the Triassic Deposits of the
Salt-range.

Vor. XXVI, 1895.

Part 1.—Annual report for 1892. Notes оп the Central Himalayas (with map and plate).
Note on the occurrence of Jadeite in Upper Burma (with a map). Оп ke occurrence |
of Burmite, а new Fossil Resin from Upper Burma. Report oz the Prospecting Opera-
tions, Mergui District, 1891-92.

Part 2.—Notes on the earthquake iz Baluchistan oz the 20th December 1892 (with 2 plates)
Further Note on Burmite, a new amber-like fossil resin from Upper Burma, Note on the
Alluvial deposits and Subterranean water-supply of Rangoon (with а map).

Part 3.—On the Geology of the Sherani Hills (with maps and plates). Оп Carboniferous
Fossils from Tenasserim (with 1 plate). Оп а deep Boring at Chandernagore. Note on
Granite iz the districts of Tavoy and Mergui (with a plate).

Part 4.— Оп the Geology of the country between the Chappar Rift and Harnai in Baluchistán
(with map and 3 plates). Notes oz the Geology of a part of the Tenasserim Valley with
special reference to the Tendau-Kamapying Coal-field (with two maps, Ол a Magnetite
Jrom the Madras Presidency containing Manganese and Alumina. Он Hislopite (Haugh-
ton) (with a plate).

Vor. XXVII, 1894.

Part 1—Annual report for 1893. Report os the Bhaganwala Coal-field, Salt-range, Punjab
(with map and 2 plates).

Part 2.—Note on the Chemical qualities of pertroleum from Burma. Note on the Singareni
Coal-field, Hyderabad (Deccan) (with map and 3 plates of sections). Report on the
Gohna Landslip, Garhwal (with 5 plates and 2 maps).

Part 3.— От the Cambrian Formation of the Eastern Salt-range (with a plate). The Giridih
(Karharbari) Coal-field, with notes on the labour and methods of working (with 2 maps
and 8 plates of sections). On the Occurrence of Chipped (?\ Flints iz the Upper Miocene
of Burma (with a plate). Note оп the Occurrence of Velates Schmideliana, Chemn.,

240 паа grandis, Sow. Se, in the Tertiary Formation of India and Burma (with 2
plates).

Part 4.—Note on the Geology of Wuntho in Upper Burma (with a map). | Preliminary notice
on the Echinoids from the Upper Cretaceous System of Baluchistan. On Highly Phos-
phatic Mica-Peridotites intrusive im the Lower Gondwana Rocks of Bengal. On a
Mica-H ypersthene-Hornblende-Peridotite in Bengal.

Vor. XXVIII, 1895.

` Part 1.—Annual report for 1804. Cretaceous Formation of Pondicherry, Some early allusions
£o Barren Island; with a few remarks thereon. Bibliography of barren Island and Nar-
condam, from 1884 £o 1894; with some remarks. —

Part 2.— Оп the importance of Cretaceous Rocks of Southern India in estimating the geogra-
phical conditions during later cretaceous times. Report on the Experimental Boring for
Petroleum at Sukkur from October 1803 to March 1895. The development and Sub-
division of the Tertiary system in Burma. а

. Part 3.—Ov the Jadeite and other rocks, from Tammaw in Upper Burma. On the Geology
of the Tochi Valley. On the existence of Lower Gondwanas zz Argentina.

Part 4.— Оп the Igneous Rocks of the Giridih (Kurhurbaree) Coal-field and their Contact

°` Effects. Ол some outliers of the Vindhyan system south of the Sone and their relation
to the so-called Lower Vindhyans. Notes on a portion of the Lower Vindhyan area of
the Sone Valley. Note оп Dr. Fritz NoETLING's paper onthe Tertiary system in
Burma, іп the Records of the Geological Survey of India for 1895, Part 2. ў

Уог. ХХІХ, 1896.

Part 1.—Annual report for 1895. Оп the Acicular inclusions in Indian Garnets. On the
Origin and Growth of Garnets and of their Micropegmatitic intergrowths in Pyroxenic
zocks (with 1 plate). Ў

Part 2.— Notes on the Ultra-basic rocks and derived minerals of the Chalk (Magnesite) hills,
and other localities near Salem, Madras (with 2—6 plates). Preliminary notes on some
Corundum localities ix the Salem and Coimbatore districts, Madras (with 7-—9 plates).
On the occurrence of Corundum and Kyanite in the Manbhum district, Bengal. On the
papers by DR. Kossmat and Dr. Kurtz, and on the ancient Geography of “ Gondwana-
land." Note from the Geological Survey of India.

Part 3.—On some Igneous Rocks from the Tochi Valley. Notes from the Geological Survey
of India. :

Part 4.— Report oz the Steatite mines, Minbu District, Burma. Further notes oz the Lower
Vindhyan (Sub-Kaimur) area of the Sone Valley, Rewah. Notes from the Geological
Survey of India. |

Vor, ХХХ, 1897.

Part 1—Annual report for 1806. On some Norite and associated Basic Dykes and Lava
flows їп Southern India (with plates ! to П). The reference of the genus Vertebraria.
On a Plant of Glossopteris with part of the rhisome attached, and оп the structure
of Vertebraria (with plates III to V). |

Part 2.—The Cretaceous Deposits of Pondicherri (with plates VI to X). Notes from the

е Geological Survey of India. ў

Part 3.—Note оп Flow-structure in an Igneous dyke (with plate XI). Additional note on
the Olivine-norite dykes at Coonoor (with plate XII). Report on some trial excavations
for corundum near Palakod, Salem District (with plate XIII). Report on the occurrence
of coal at Palana village in Bikanir State (with plate XIV). An account of the geolo-
gical specimens collected by the Afghan-Baluch Boundary Commission of 1896 (with plate
XV). Note from the Geological Survey of India (with plates XVI and XVII).

Part 4.—On Nemalite from Afghanistan. On a quartz-barytes rock occurring in the Salem
District, Madras Presidency (with plate XVIII). Note on а worn femur of Hippopotamus
irravadicus, Саш. and Falc., from the Lower Pliocena of Burma (with plates XIX and
ХХ). On the supposed coal at Jaintia, Ваха Duars. Percussion Figures on micas.
Notes from ihe Geological Survey of India.

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