146 
B. Smith—Ball or Pillow-form Rocks. 
having the composition of some of the ‘ adamellites’ or ‘ granodiorites’ 
would have a composition even nearer that of the obsidianites, the 
chemical difference that, I gather, Dr. 
Mueller deems esas of 
the obsidianites not being of terrestrial origin, does not appear to be 
A stronger objection to a terrestrial origin for 
of great importance. 
these Singapore specimens is ‘their weight. 
Pumice from Krakatoa 
OBSIDIANITES. OBSIDIAN. 
2, i 
a) Lies | British 
ao 5 Australites. | Billitonites. | Moldavites. U.S.A. Hast 
a5 3 Africa, 
ne = : 
_@)_|_Q) (8) (4) (5) (6) (7) (8) (9) (10) (@11)_}) (12) © as) 
Si Oo» 69-80)70-90|64- 68/77 - 72/70-92|71 - 14/77 - 69/82 - 68]75 -52)74- 52/76 - 20/64 -00/70-61 
Ale Oz . |14-30/13-50/16-80|) 9-97/21-20/11-99)12-78) 9-56)14-11)13-72|13-17|10-43) 8-59 
TiO,g .| 1-00) 1-00; — -86; — — = = = = == °78) -15 
FeO .| 5-65) 5-47] 1-01) 3-75] 5-42) 5-29) 1-45) 1-13) -08 62 73| 3-86! 5-96 
Fe, Oz . -15) -32| 6-57) -32)| 1-07) — | 2-05) — | 1-74) 1-01) -34] 6-30} 2-52 
MnO .|trace|trace| -20/trace} -41} +32) — -18} — |trace| -10} -37| -34 
Ca O 2-61) 2-35] 3-88) 2-40] 3-78] 2-84) 1-26) 2-06) -78| -78| . -42) 1-45) -61 
MgO .| 3-20) 2-45} 2-50) 1-57) 2-61} 2-38] 1-15) 1-52) -10} -14) -19| -34) -07 
NaoO .| 1-16) 1-46 trace] 1-29) 2-46) 2-45) -78| -63 3-92) 3-90) 4-31) 7-59] 6-77 
KeO 1-90 2-17) 4-01) 1-96) 2-49) 2-76) 2-78) 2-28] 3-63] 4-02) 4-46) 4-59) 4-46 
has floated to the east coast of the peninsula, but the idea of these 
obsidianites having floated to the peninsula attached to masses of 
pumice is precluded by the absence of any pumice of similar 
composition; and one cannot admit that bodies of this weight could 
drift in the upper atmosphere any more readily than one can admit it 
of arifle bullet. A cosmic origin seems the only possible explanation. 
II.—Bat or Prttow-Frorm StRvucTURES IN SANDSTONES.? 
By BERNARD SmiTH, M.A., F.G.S. 
fW\HE structures described below occur in 
monotonous and generally uninteresting type; namely in 
sandstones, interstratified with masses of shale and mudstone, exposed 
near the centre of the Berwyn Anticline in parts of Denbighshire. 
The necessity, however, of examining every exposure, incumbent 
upon the Surveyor, has led me to pay attention to detail, and 
especially to certain phenomena that would appear to be of world- 
wide occurrence in sediments of all ages. 
Description of the Sandstones. 
The sandstones are of both Llandilo and Bala age. Those of 
Llandilo age occur sparingly in a mass of scantily fosellinerone shales 
in the Llanrhaiadr- ym-Mochnant district, but become more important 
when followed eastward along the strike in the direction of Llansilin. 
In the same districts the Bala Beds are more prevalently sandy, and 
the strata are of a more regular character. 
1 With the permission of the Director of the Geological Survey. 
rocks of a rather 
