October 2nd.—­Seh-Baba.  Spiraea belloides, commonish on limestone rocks in the ravine near the road which leads from Tazeen valley to Khubur-i-Jubbur.  This limestone is in thin strata; the strata are subdivided by quartzose veins, they occur generally at a dip of from 15 to 20 degrees, but are occasionally quite vertical or highly wavy, presenting evidence of concentrated force upwards.  The outcrop wears an uniform aspect, and occurs to the north of the ravine.  The south here and there presents sheets of rock, the overlying strata having slipped off.  The strike of the strata is north and south.

Coal is said by Hatchet to be formed chiefly from the resinous principles of plants,—­this would account for its appearance when burnt, which is the same as that of burnt bitumen.  But resinous principles are, even when they exist, of partial extent only in plants.  In good coal the whole of the vegetable substance seems to be transformed, a supposition barely compatible with Hatchet’s idea.

To study this, extensive examination of coal in all degrees of formation would be necessary, beginning with the wood so curiously changed by the Brahmapootra, i.e. brown coal occurring in its sand banks, and which has a very peculiar and disagreeable odour when burning.  It would also be necessary to examine how far the coal-plants exhibit vegetable structure, are they mere impressions or are they the plants themselves changed?  To what extent do these agree with coal?  What particular plants and what parts of these appear to have formed coal?  Its fibrous structure would hint at formation from the woody system, and it is not incompatible with the deliquescence of a thick layer of drift.

The plants of coal fields having been drifted, can only give us an idea of the vegetation along the natural drains of the then country, such may by no means have had one universal character.

The plants of the open surface of modern tropical countries being generally different from those along the beds of streams, in which situations now-a-days Equiseteae, Lycopods and Filicis are chiefly found.  Coal being drift, it follows that the plants of the coal fields can give us no information on the distribution of vegetables in those days; to gain information on this, the fossils should be in their original situation.  And there again an obstacle may exist in our not being able to ascertain the height or level of that situation.

If the plants of coal fields are found to be converted into coal, then the only difference between coal shale, and coal will consist in the very small proportion of vegetable matter in the former.

The small number of coal plants, i.e. the small number of species, at once points to the supposition that fossil plants are confined to those of the most indestructible nature:  here again is another sign of this in the preponderance of Ferns, which Lindley finds to be the most permanent.