"ملف ١/٥ III شركة نفط الكويت" [و‎‎١‎٤‎٦] (٧٦٦/٢٩٦)

■ ' ( 4-6
( 10 5
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a preference for aragonite on the purt of the silica solution.
Underneath the hard cap fomed by the chert- Uaeetone bed,
the Kowtit grits arc again found in the usual incoherent
condition, with calcareous nodules. Alteration to Chert is
entirely a superficial phenomenon, and is confined to rocks
rich enough in Calcium Carbonate to be called limestones.
Tt sccois clear that the same siliceous agent which changed
lijaeetone to cnert, changed the ieos calcareous grit into a
quartzite*
(24-}. Mr.Lister James* description of jebei crain leaves
no room for doubt that the Koweit series is found ther also
?*ith a cap of Kandy lim> stone tartly replaced by chert. The
silicification surface thus appears a© a plane, rising from
roweit, *fcere it is found at 5 o ft. above sea level, or even
less, to Mishrif (loo ft), over Jebel \mxmh and the Burgan
hills, \hich must be about JoQ ft. to Jebel ^rain (perhaps
400 ft). The nature of the si Unification process is not
clear. C*K.Leith has recently { .con.Geo 1 XX, 6 , 1925 p .513 -
523 } remarked on the frequent association of erosion surfaces
and silicification; and aiiicification of surface rooks has
been described from the Kalahari desert of southwest Africa.
Silica appears, under appropriate conditions, to be a
relatively soluble substance. But the best known condition for
the solution of silica is the re^ence of Alkalis, it is just
conceivable that sodium carbonate waters coming; from the
granites of the Interior of Arabia may have been brought into
action on thin elongated, and comparatively narrow strip of
the Foweit series, by some accident of drainage after dopesi*
tion had ceased. Thin is, of course, entirely a speculative
idea, but it explains the apparent absence of chert and
quartzite elsewhere in the roweit series. The superficial
position now occupied by the Mishrif chert &nd the Borgan -
Warah quartzite would be due, on this line of reai oning, to