oct. — dec. J 856.] The Natron Lake of Loonar. 7 



[Further communication from Dr. Smith, accompanied by a plan and section 

 of the Lake.] 



In the plan now submitted, the crateriform shape of the hollow 

 is well seen, and if the opinion of some Geologists be correct, 

 namely, that this hollow is the crater of an extinct volcano, the in- 

 terest felt in it must be deepened by the fact, that, in all probabi- 

 lity it is the only one in southern India. 



The action, however, even of a large crater like this must have 

 been comparatively limited, other vents and fissures, which have 

 left no permanent mark of their existence must have given exit 

 to those vast sheeted masses of porous and solid rocks consti- 

 tuting the trappean plateau of the Deccan. This plateau over 

 lying primary and secondary rocks to depths varying from a few 

 feet to 300 probably, covered with a rich mantle of inexhaustible 

 black soil, and capped here and there along its eastern indented 

 edge with laterite patches, extends from 17° to 27° N. L. and from 

 72° 30* to 79o e. L. 



It may be interesting to remark, that at the South East angle 

 of the plateau, the existence of numerous hot springs seems to in- 

 dicate the persistence of igneous action. Taking Loonar as a cen- 

 tre, and with a radius of 150 or 200 miles, the quarter circle ex- 

 tending from the North East to the South East, will be found to 

 include (a) the tepid spring of Beder, rising from the base of a 

 laterite cliff; (b) the hot springs at Kair on the Pain Gunga (87 Q 

 Bradley) and (c) the hot springs near Labbundee (102° Bradley) 

 lying in a North Easterly direction. 



