158 
Transactions Texas Academy of Science. 
Hill^ Eobert T. 
eruptive material. (The largest portion of the area, however, oonsists of 
extensive flats lying between the mountains, which are shown to be almost 
vecent lake beds drained of their waters, except in rare instances, where 
salt lakes still occupy limited portions of these basins.' The Quaternary or 
later sediments of these former lakes are -described as the Eagle Flats for- 
mation.” 
221. , lanidJ Dumble, E. T. 
The Igneous Eocks of Central Texas. (Abstract.) 
Proc. Amer. Assoc. Adv. of Science, Vol. XXXVIII, p. 242. 
1890. 
“Pilot Knob, Travis county, Texas, is described as the type of an inter- 
mittent line of basaltic rocks often of columnar structure protruding 
through the lOretaceous limestones of Central Southern Texas from east 
of Austin to the 'Eio Grrande. The age is shown to be Post-Eocene, and 
the name iShumard system is proposed for this hitherto unclassified erupt- 
ive topographic feature. 
“These eruptives ( ?) extend a little north of east from the Rio Grande 
in the vicinity of Fort Clark to Austin, Texas. The isolated eruptive areas 
of Rockwall county, Texas, and Pike county, Arkansas, are in line with 
this system, and probably all are along a line of weakness in the earth’s 
crust which has apparently existed in this region. The time of the erup- 
tion is shown to have been Post-Eocene.” 
222 . 
The Geology of the 'Staked Plains of Texas, with a Description 
of the Staked Plains Formation. (Abstract.) 
Proc. Amer. Assoc. Adv. of Science, Vol. XXXVIII, p. 243. 
1890. 
“The Staked Plainis are shown to be an extensive mesa, which was an 
interior base level in late Tertiary or early Quaternary time. Its surface 
is covered by a fresh- water lacustral sediment, consisting of loam and 
gravel, for which the name of the Staked Plains formation is proposed.” 
223. 
The Geology of the Valley of the Upper Canadian from Tascosa, 
Texas, to Tucumcari Mountain, Xew Mexico, with Xotes on the 
Age of the Same. (Abstract.) 
Proc. Amer. Assoc. Adv. of Science, Vol. XXXVIII, p. 243. 
1890. 
“This valley is shown to have been a more ancient piece (of) erosion 
than that accomplished by the present river which flows through it. It is 
from forty to sixty miles wide and eight hundred feet beneath the ancient 
base level of the Staked Plains, and filled with a detrital deposit, for which 
the local name of the Terra Blanca formation is proposed.” 
