Review of Recent Geological Literature. 51 
occurs on its surface and we note that Prof. Hill takes a rather con- 
servative view and speaks cautiously in regard to the existence of 
artesian conditions generally in the Llano. He says: "That the under- 
ground water-sheet of the Llano beds can be struck throughoul the ex- 
tent of the mesa has been demonstrated. But it is also apparent that 
since this water occurs in a surface formation — the Llano beds — there 
can be no hydrostatic pressure to force a surface flow. Hut there are 
other strata underlying portions of the Llano, beneath the Llano water- 
sheet, and to these'we have cause to look with much hope that they 
may present favorable artesian conditions Without 
committing myself t<> prophecy, it is my opinion that, when the por- 
tion of the Llano along the Texas-New Mexico line is thoroughly pros- 
pected, somewhere in that region will be found an abundant artesian 
supply from the underlying Dakota and Trinity sands." 
In regard to the Trans-Pecos region, in spite of the unpromising as- 
pect of this high plain. Prof. Hill speaks much more confidently of the 
existence of water at a moderate depth, about 200 feet, which, however. 
does not rise to the surface and therefore is not artesian, except in 
certain districts. Agriculture may therefore be possible to a limited 
extent there. 
Space forbids following Prof. Hill into the question of the water- 
supply of the mountains, or Prof. Hicks into that of Nebraska. The 
same may be said of Prof. Culver's work on the Black Hills. There can 
be little doubt that continued investigation and adventure will gradu- 
ally extend the cultivable lands of the wesl far into what was formerly 
called the Greal American Desert, and that many thousand square 
miles will be reclaimed. There will, however, probably always remain 
Large areas whose reclamation would cost more than they could ever 
repay. Farming will press hard on the possibility of subsistence, and 
occasional series of very dry seasons will from time to time set back the 
surging tide of immigration with their ••Thus far but no farther." 
E. w. C. 
Tin Colorado Formation inn/ it* Invertebratt Fauna. By T. W. Stan- 
ton. U. S. Geol. Survey. Bulletin 106; 288 pages, 15 plates. 1893. The 
formation here described comprises the Fort Benton and Niobrara di- 
visions of the Cretaceous series made known by Meek and Hayden in 
the upper Missouri region. Only some 25 or 30 species of invertebrates 
had hern definitely assigned to ii previous to Mr. Stanton's collections, 
chiefh in 1890, of the fossils of Huerfano park and adjacent Localities in 
southern Colorado. These collections, and their comparison with equiv- 
alent beds in other parts of the United state-,, bring the total known 
invertebrate fauna of the Colorado formation up to about 150 species, 
including 39 that are believed to be new. The fauna as a whole is 
regarded as the approximate taxonomic equivalent of the Turonian in 
Europe. \\ i 
.1 Geological Reconnoissana in- central Washington. \'<\ I.e. Russell 
I*. s. Geol. Survey, Bulletin 108; 108 pages, 12 plates, s figures in the 
text, 1893. This exploration was undertaken for the purpose of ascer- 
