Correspondence. 269 
of the country is much more than this. The country intervening be- 
tween Nampa and Glenn's Ferry is completely enveloped with lava, 
and rises about 600 feet higher than either of those stations. In a 
ravine coming into the Snake river at Glenn's Ferry I found an ex- 
tensive exposure of beds of sandstone and clay consolidated into rock 
underlying the lava deposit, and containing shells in great abundance. 
From a stratum of this sandstone about four feet thick, and more than 
ICG feet below the bottom of the lava, I brought home a collection of 
shells which I submitted to Mr. Dall, who kindly gave me the follow- 
ing report upon them: — 
Washington, Dec. 30, 1890. 
Dr. G. F. Wright. 
Dear Prof. Wright. 
The fossils in the rock submitted to me are: Goniobasis taylori 
Gabb (sp.), Lithaiiaantiqiia Q,3\jh, Latia dalli "S^h^t^, Sphcerium ida 
Iioensis Meek and S. negosmn Meek. These fossils characterize the 
"Idaho formation" of Cope; the rocks belong to the sedimentation of 
Cope's "Idaho lake" and are Pliocene, very likely Middle or later Plio- 
cene. These rocks were synchronized at one time with King's Truckee 
group, formerly referred (on very insufficient evidence) to the Mio- 
cene. 
Yours truly, 
Wm. H. Dall. 
The problem next is to determine the relation of these Pliocene 
deposits to the Nampa beds. The younger age of the Nampa beds is 
indicated, as Emmons suggested, (i) by their unconsolidated condi- 
tion; for, though this may not be absolutely conclusive, it is difficult 
to account for the consolidation of the Glenn's Ferry deposits, so near 
by, except through influences of long-continued activity. (2) The ele- 
vation of the Glenn's Ferry bed above those at Nampa amounts to 
about 400 feet, as shown by the following comparative tables: 
Elevations at Nampa. Elevations at Glimn's Ferry, 
Railroad Station 2489 2566 
Lava stratum (bottom of) 2414 2800 
Bottom of well 2 161 
That is, the vegetable soil at the bottom of the Nampa well is 639 
feet lower than the level from which these shells at Glenn's Ferry were 
obtained. The evidence, therefore, that these Nampa sands and clays 
are younger than the Glenn's Ferry consolidated clays and sands would 
seem to be conclusive. The appearances indicate that the Nampa beds 
occur in a basin which has either been eroded out of Pliocene de- 
posits synchronous with those occurring at Glenn's Ferry, or in a 
l)asin formed by the elevation of the Glenn's Ferry strata connected 
with other elevations of whfch we have at present no definite record. 
Evidently, also, the deposits at Nampa were formed by a rapid pro- 
cess. The quicksand beds recorded in the well were respectively of a 
thickness of 100 feet, 40 feet, and 30 feet. 
