26 MIDDLEMISS: THE GEOLOGY OF THAI; STATE. 



gneiss, but it was impossible to be sure that this was not deceptive 



and due to small undulations of the latter. 



At one place, 1 mile due east of Walren, there Is a detached 



outlier of the Delhi Quartzite forming a capping to a little N. — 8. 

 ridge and entirely surrounded and underlain by the biotite-gneiss. 

 In certain places along the main junction, — and especially \ 

 Blocks of Delhi t0 ' mil( ' E.N.I, of Dijio— the edge of the 

 Quartzite in the alluvium of the river-valley is bounded by 

 biotite-gneiss. i r.v r ,i ■< ■ .-, • i 



low culls of the motite-gneiss. whose upper 



layers over wide areas are roughly horizontal and undulating 

 with the foliation of the rock. These upper layers are intruded 

 by the aplite. varying in coarseness, and among it are forced or 

 included tongues and numerous patches of the gneiss. Amono 

 them both also, and prominently among the biotile-,<jneiss. are 

 innumerable small and large included blocks and masses of the 

 Delhi Quartzite. which as a formation, a little further along 

 comes normally into the section in situ above this junction layer. 

 Some of these blocks and masses were found to be ] foot or so 

 across and looked like great " eyes " followed round by the 

 foliation of the gneiss. Others were long and narrow, i to 5 feet 

 long, lying with the foliation, and others again oriented in any 

 direction. But the most characteristic were the large masses 

 (several yards across) of the quartzite, arranged with their original 

 bedding vertical, and as it were " planted '* thus among the nearly 

 horizontally inclined foliation of the biotite-gneiss (see PI. 2, figs. 1 

 and 2). The original bedding of the <piartzite was always well 

 shown in the blocks by ordinary stratification banding and also 

 by rows of cavernous pittings and hollows, coated with limonite, 

 which represent lines of weathered-out minerals (see text figs. 3 

 and I). These characteristic cavernous hollows were seen to be not 

 only a marked feature of the blocks distributed in the upper 

 layers of the biotite-gneiss, but also of the lower layers of the 

 Delhi Quartzite which comes in situ above it up to a height of 

 ]() or 20 feet at least. One may walk for hundreds of yards over 

 uninterrupted outcrops of the. Delhi Quartzite. finding quantities of 

 this cavernous variety of the rock. 



Specimen, No. ^ (12290. PI. 9, fig. 5) is an example of a portion 

 Secondary minerals of ono °* tnose blocks, broken out from the 



<ieve^,>e<l in th( . centra ] p 0rt j on f j t so ag to ggj. be j ()w the skin 



of weathered rock. Besides the predominant 



