December i, 1883.] 



THE TROPICAL AGRICULTURIST. 



439 



the quartz bed blasted. Thia revealed a beautiful 

 thin vein of mundic from 1 to 2 in. in width, and 

 alongside of its quartz matrix a vein of iron ore 

 about 1 ft. in thickness, largely impregnated with 

 crystals of the arsedical mineral. Some of what ap- 

 peared to be the purest specimens of it, as well as 

 the quartz matrix in which it was found embedded, 

 were assayed in my laboratory, and showed appre- 

 ciable quantities of gold. 



What may be the lithological composition of the 

 highest of the Travancore Ghauts I cannot precisely 

 say, as my instructions kept me quite within the 

 spurs, but the most elevated of those rock masses 

 which I examined are most certainly a very quartzose 

 form of giieiss, and at this rock and its bomologues — 

 quitrtz rock, mica-schist, and clay-slates— most usually 

 accompany the older igneous rocks, I have come to 

 the conclusion that the highest and mors barren peaks 

 of Travancore, like those of the Wynaad and Xeil. 

 giri ranges, are probably granitic. Gneiss rock then 

 in its eeveral varieties may be said to be the rock 

 par excellence of Travancore, In the southern portion 

 of Assamboo district, in the neighbourhood of Retreat, 

 Little Valley, Glenmore, Glenbeg, Corriemcny, Sea- 

 field, Ballamore, and Hillside estates, and along what 

 is locally known as the Great Valley, we have the 

 more compact and quartzitic variety largely studded 

 with the common garnet, and less of the quartzose 

 form ; but from the Great Valley northwards along the 

 district road to Agustier, Glenelg, Bon Accord, and 

 Oaklands estates, and further through Merohiston, 

 Balloclibuie, Stiathmore, and Glenista onwards to In- 

 vernettie estate in the Knlratti district, those two 

 leading varieties of gneiss rock alternately predominate. 

 Occasiunally, however, there are found the other 

 rocks of the nietamorphio series — mica-schist and 

 clay-slate. On the opposite side of the great gorge, 

 travelling from Oaklands bungalow to that of the 

 esiale conductor at Kildona, there is a most re- 

 markable instance of sudden transition from the quart- 

 zose form of gneiss to the fine grained and light yel- 

 lowish fissile and quartzitic variety which so much re- 

 sembles hard coaipact sandstone. As the ravine is 

 entered there is a, bold escarpment of the quartzose 

 vaiiety several hundred feet in height, with an al- 

 most horizontal dip, «hich rapidly increases until as 

 the quartzose characteristics are lost, and the bun- 

 galow is approaclied, the beds become almost vertical. 

 The mica-schist group, I did not hud largely re- 

 presmted, but it crops out in some of its varieties, such 

 as chlorite and liorublcndic schists to a greater or 

 lesser degree at Auldbar and at certain points along 

 the district road between the lattn place and Inver- 

 nettie estate. On the left front of the superinten- 

 dent's bungalow at Auldbar there ate interesting out- 

 crops of this group. As might be expected in a 

 country where the uietamorphic system of rocks is so 

 well represented as in Travancore, the minerals which 

 li sunlly accompanj' it would aUo be present in a cor- 

 responding degree. Thus talc, ln>rnbleude, chlorite, 

 and actyUolite, and several varieties of febpar may be 

 met with in almost any portion of the country from 

 Inveruettie iu the north to Mahtndrighcrry in the 

 southern portion of Aseaaiboo district ; but what 

 struck me most was the size, beauty, and variety of 

 colour of the felspars ; some of tLein paj-siug from the 

 dull yellow of the orthoclasic variety to the pale 

 green of talc. Indeed were it not for the toftncss 

 of the latter mineralsonie of the Travancore felspais 

 might readily be mistaken for it, especially in cases 

 where the outlines of the felspathio crystals are not 

 very clearly defined. Magnetic oxide of iron is not 

 only present in abundance iu the nietamorphio rocks 

 of Travancore, but it may be seen to even a greater 

 extent in the coft'ce soils on the mountain slopes, as 

 well as ia the soils of the low country and along the 



road sides after a shower of rain. In walking along 

 the sea-shore at Colachel, and watching the waves of the 

 Indian Ocean break upon their sandy beach, I was 

 much struck with the very great quantity of this 

 mineral, which in wreath-like masses became exposed 

 to view as the waters of each spent wave receded to 

 their briney source. Graphite or plumbago, which 

 is one of the most valuable minerals belonging to the 

 metamorphic system I have also met with. In the 

 low country in the neighbourhood of Trevandrum, the 

 capital, I am informed that there are very satisfactory 

 and extensive beds of this substance, and samples al- 

 leged to have been taken from some of these beds I 

 have had submitted to analysis in my laboratory, aud 

 found them to be of first-rate quality, as indeed their 

 appearance indicated. 



Having now briefly noticed the geological and mine- 

 ralogical characteristics of the Wynaad and Neilgiri 

 dittricts, aud so far compared them with those of 

 Travancore, ;I shall proceed to notice the quartz out- 

 crops of the latter country so far as my survey of it 

 enables me. What I have quoted from the several re- 

 ports already mentioned shows that the greater portion 

 of the rocks of the Wynaad, Neilgiri, and Travan- 

 core districts of India belong to the metamorphic sys- 

 tem, and whgU it is considered that this system em- 

 braces the g ei^s, quartz-rock, mica-schist, and clay- 

 slate groups, and that I have shown in the preceding 

 articles that the former group greatly abounds, and 

 the two latter to perhaps only a small extent in 

 Travancore, it might reasonably be expected as a 

 consequence that somewhere iu that country the quartz 

 rock group, as well as quartz veins, would be found. 

 As previously noticed such actually is the case. 



Ketreat Estate. — First then in Assambco district, at 

 the northern extremity of Ketreat estate, which be- 

 longs to Mr. G. Thornhill, and above that point 

 where the main river which forms its western boun- 

 dary is joined by one of its principal tributaries, 

 there have been laid bare by the rapid river currents 

 which obtain during the south west monsoon period, 

 several masses of syenitic rock along with beds of a 

 reddish brown ironstone of apparently poor quality. 

 Nearly at right angels to the direction of the river 

 course there intersects the upper masses of syenitic 

 rock, a band of quartz about 7 ft. wide, and which 

 at its sides is impregnated with large crystals of 

 felspar ; these crystals increase in quantity as the 

 quartz mass loses itself iu the syenitic matrix. Its 

 strike is N.W. and S.E., and it narrows to a width 

 of about 2 ft- as it loses itself in the jungle, which is 

 on the western side of the river. It has been traced 

 for a distance of about 10 yards, and its dip, as far 

 as I could ascertain, is nearly vertical, the felopathic 

 constituents which, as already noticed, are largely 

 present in tliat portion which is exposed in the river 

 bed become fewer or disappear entirely at the point 

 where it enters the jungle. Were it not for this fac; 

 it might be misakeu for a vein of graphic granite. 

 About 15 yards below this point, or near the junc- 

 tion of the tiihutary with the maiu stream, there 

 is anoth-r outcrop of quartz from 1 ft. to 2 ft. in 

 width running through what appears to be the same 

 syenitic rock, striking in N. W. direction, and hav- 

 ing like the one alr'ady noticed an a'most vertical 

 dip. A few yards below the junction of the two 

 streams there intrudes another vein of pure quartz 

 ab mt 1 ft. to 2 ft. in width, striking N. W. and 

 S. E, ,aud throwing out a branch or leader of nearly 

 similar dimensions, which takes au east and west 

 direction, and has also a nearly vertical dip; aud 

 a little above this again .another vein is exposed for 

 a distance of about 12ft. running east and xvest and 

 having a bluish-pink colour. The first and second of 

 these quartz outcrops where bh-isttd to a depth of 

 12iu., and selected samples roasted and treated with 



