"تقرير عسكري عن جنوب غرب بلاد فارس، يتضمن أقاليم خوزستان (عربستان)، لورستان، وجزءًا من فارس" [‎٣‎٥‎٩] (٤٦٦/٤٠٦)

359
When in immediate proximity to the igneous rocks, it becomes almost
felack, and is traversed by innumerable threads and thin veins of white car
bonate of lime. Mountains of this character rise very abruptly from elevated
plateaux of rich alluvial soil, and are, as it were, pinched up at their summits
into jagged and well-denned angular peaks. Many of the beautiful plains
between Ispahan and Hamadan are bounded by picturesque ranges and soli
tary peaks of this limestone.
The lithological character and homogeneous structure of these rocks are
everywhere, however, so precisely similar as utterly to preclude the possibilitv
of my pointing out any decided line of geological demarcation (although their
western boundary is tolerably well defined) ; and it is to the fossil contents
therefore, that we must look for information.
It may be imagined that in deposits so altered and metamorphosed as
these are, the presence of organic remains is exceedingly rare. I have been
so fortunate, however, as to meet with a few fossils; and, although these
are very indistinct and contorted, I satisfied myself at the spots m which
they occur (except in one instance) that they rather belong to the tertiary
than to any earlier geological period. The really characteristic forms of
nuMMulitcs and their allies it is true are absent, but so are also (itumou it68 and
the peculiar fossils of the secondary and older rocks. At Bisitun I observed
a large buccinoid shell, at Persepolis, near the tombs of the kings, are oslrea,
mdiim, turritella, films'?, echinites, and zoophyta more abundant than in
any other observed locality of this rock.
It may be objected to my supposition of these rocks chiefly belonging to
the tertiary period that they for the most part rise too boldly from the plain,
and constitute a too well-defined north-west and south-east line invariably to
the east of the undoubtedly cretaceous deposits; that, while the mountains
composed of nummulitic rocks have their sides and frequently their summits
clothed with rich forest trees, the blue crystalline limestone is totally devoid
of trees, and generally of vegetation; and that the jagged and serrated crests
of the latter form a remarkable contrast with the smooth and icgular
outline of the former. These differences might appear to point to a difference
in the geological age of the two rocks, but they may surely be accounted for
by the abrupt fracture and separation of their masses during elevation and
crystallization, and by the altered state of those portions in proximity to the
igneous axis.
I do not, however, insist upon the correctness of my assumption; it must
rather be considered as a provisional arrangement, until further information is
obtained to enable us to decide satisfactorily on the subject. At present we
have very insufficient data to enable us to determine the question.
a Tang8^ or transverse clefts in the limestone saddles. —before quitting
the subject of tjie nnmmulitic rocks 1 must not omit to mention the numerous
and enormous clefts which pass through the elongated limestone saddles.
These clefts, or ^ tangs ^ (as they are called in Persian), are the most
peculiar feature of the nummulitic rocks.
< All the great rivers which fall into the Tigris from the east rise in the
interior of the Zagros ; and, as their course is generally from north to south,
they cross the ridges of the great chain diagonally. The manner in which
this is effected is very remarkable. Instead of flowing in a south-east direction
along the trough which separates two parallel limestone saddles, and by this
Cleans working out their channel in the soft rocks of the gypsiferous series, or
alluvium, and afterwards rounding the end of the saddle at the point