164 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
The Pueblo-Stein Mountains. — By taking a three-day dusty stage ride 
northward from Winnemucca, Nev., I was enabled to give a week to the 
study of the Pueblo and Stein mountains that cross the Nevada-Oregon 
boundary a little west of the north and south line marked by the post- 
offices of Denio and Andrews. The stage road carried me past the Santa 
Rosa, Jackson, and Pine Forest ranges, of which some mention has already 
been made. The route for part of the distance lay on the dead-level 
gray silt plain of the extinct Lake Lahontan, whose successive shore lines 
were traceable at various heights on the enclosing slopes. A long gravel 
spit, hooked to the east at various levels, stretched northward from the 
Jackson range to Mason’s crossing of Quinn river. 
The general result of this week’s work gave me the impression that 
the Pueblo-Stein mountain range is more eroded than would be in- 
ferred from Russell’s description of it (b, 439,444) ; but there can be no 
reasonable doubt that it represents a long fault block. The following 
pages contain a direct statement of the evidence to this conclusion, with- 
out analysis of the method by which the conclusion is reached. The 
analysis has been sufficiently stated in the preceding pages; its results 
may now be employed without restatement of the method of reaching 
them. This is the historical order in the development of methods of 
investigation, with the time element condensed. When a geologist now- 
adays describes vertical strata of conglomerate as of sedimentary origin, 
he does not again go over de Saussure’s argument concerning the con- 
glomerate of Valorsine; when a physiographer now asserts the occurrence 
of a subsequent valley on the evidence of stream course and rock struc- 
ture, he need not repeat the argument by which subsequent valleys were 
first explained by Jukes in the basin of the Blackwater. These are set- 
tled questions and may therefore be treated by the short and direct 
method that steps at once from observation to conclusion. So may the 
question of block mountains be treated by the short method, provided 
the complete method has been tried and found valid. 
The Pueblo mountains of Southern Oregon, Figure 14, overstep the 
state boundary at Denio and extend about ten miles southward into 
Nevada. They trend northward to a high dome 15 miles north of 
Denio, and then fall off in a broad westward re-entrant back of Doane’s 
and Field’s ranches. The high serrated range north of the re-entrant is 
the beginning of the Stein (or Steen) mountains. The Pueblo mountains 
consist of two ranges for most of their length. The eastern or front 
range, Figure 15, is made of ancient crystalline rocks, such as diabases 
and mica schists. The western or back range is made of bedded lavas, 
