14 MALONE JUKASSIC FORMATION OF TEXAS. [bull. 12(50. 
of the Trio or that of the Truncate mound toward a common lineJ 
the axis of a closed fold, where they stand nearly vertical, and where 
is the shallow beginning of a small draw that deepens to the north! 
ward. This pinching and change of dip make difficult a close esti- 
mate of the thickness of upper Theta strata here exposed, but it does 
not seem probable that less than about 250 feet of these can have been: 
involved in the exposed portion of either limb of the fold. 
If we except obscure vestiges of fossils in the Kappa limestones 
and fragments of Paleozoic fossils (partly corals) in the pebbles of: 
the Iota conglomerates, the fossils at this locality are confined to the! 
Theta subdivision. 
A very few forms, two or three of them identifiable as the com! 
monest Malone species, were collected in the upper part of the Theta 
chiefly in one bed of slight thickness, at a spot near the southwestern] 
base of hill (\ at the south border of the flat, saddle-like interval; 
that separates the Trio from the west-northwestward continuation 
(.1, B) of this hill range. In tin 1 immediate vicinity of this minor 
occurrence of fossils, and stratigraphically lower, is a small exposure) 
of gypsum. This locality is only about half a mile west and a little 
north of the principal collecting ground above described. 
The Iota subdivision of the Trio section consists distinctively ol 
coarse conglomerates, in six or more beds 1 to S feet thick, separated 
by layers of relatively soft sandstone. Many of the pebbles and j 
cobbles in these conglomerates are of iron-stained chert and siliceous i 
limestone; some are evidently of Paleozoic derivation, and a few ari^ 
of white quartz. In the southeastern slope of the east hill of the | 
Trio the thickness of the Iota is about 50 feet. In the Truncate 
mound a considerable part of the original thickness has been removed! 
The dip of the Iota, like that of the other and generally much dis- 
turbed members of the Malone formation, is extremely variable in 
amount and direction. In the Trio and the Truncate mound it is 
usually from 15° to 25°, but exceeds the latter amount in places. On 
the southeastern slope of the Trio its direction is a few degrees west 
of north; in the east and west walls of the Truncate mound it is,* 
respectively, west and east. 
At the isolated hill {G) south of the railway, between one-half and 
three-fourths of a mile southeast of the main fossil-bearing locality* 
no fossils were found, nor any Malone rocks lower than Iota, though 
the typical succession of conglomerates of the latter subdivision it 
shown there, blanketed by Xeocene at its base. 
The Kappa, which forms the upper portion of the Trio— about 40 
feet in hill E — is of hard, massively bedded, bluish-black, calcit* 
seamed limestone, charged with irregular segregations or impregnafl 
tions of silica and iron. Much of it is cleft into large, rectangulai} 
