zontal basaltic commas. The hill has been cut away, to form the great military road. In making the escarpment, the balls were met with, and it being impossible to cut through the nuclei in vertical sections, it was either necessary to leave them projecting or to remove them altogether: in the latter case cavities remained equal to the hemispheres of the nuclei; and the vertical sections display from ten to fifteen concentric layers of friable gray stone, which in some instances I have found to affect the needle. I compared specimens of the nuclei with a mass brought by me from the Solfatara at Naples, and found them quite similar in aspect, colour, hardness, and great weight. This formation excited the attention of those gentlemen who have visited the northern and eastern parts of the great trap region;[1] but Dr. Voysey was quite mistaken in supposing it formed the basis of the western ghats. Captain Coulthard speaks of it in Sagar[2]. Major Franklin also noticed it in the trap of Sagar, in lat. 23° 51′, and long. 78° 44′, at 1933 feet above the sea, as "frequently globular; the nuclei of the decaying masses, varying in size from an egg to a large bombshell, and their decomposing concentric lamellæ being generally very thin, and often very numerous."[3]
Dykes.—I now pass to the basaltic dykes, several of which came to my notice in different parts of the country. They are all vertical, and I did not observe that they occasioned any disturbance or dislocation in the strata of basalt and amygdaloid, through which they passed.
Two dykes run obliquely across the valley of Karleh (thirty-five miles north-west of Poona), and intersect each other: they are about four feet thick and cut amygdaloidal strata. A prismatic disposition it
- ↑ Dr. Voysey says, "The nodular wacken or basalt is one of the most common forms of trap in the extensive districts composed of the rocks of the family south of the Nermada (Neibuddah) river. It occurs perpetually in the extensive and lofty range of mountains (the Gawalghur), situated between the Purna and Tapti rivers, and appears to form their principal mass. It is found equally abundant throughout the whole of Berar, part of the provinces of Hyderabad, Beder, and Sholapoor, and appears to form the basis of the great western range of trap hills which separate the Konkun from the interior of the Dukhun."—Physical Class, Asiatic Researches, pp. 126, 189.
- ↑ "The base of the hills is invariably broader than the summit; and if the sides of a hill are smooth and even, balled trap, often a concentric lamellar variety will be the principal component matter, decomposing and decomposed into a predominating workable clay, still showing the parallel converging layers."—Physical Class, Asiatic Researches, p. 7(illegible text).
- ↑ Physical Class, Asiatic Researches, p. 30.
