Laws of New Mexico Mountain Ranges. — Henick. 303 
To return to the Magdalenas, the writer pointed out the 
main facts in this complex range in a brief paper published in 
the American Gkologist for April, 1897. To what was said 
in that brief description it is not necessary at this time to add 
descriptive details, particularly as a full account, with sections, 
is in course of preparation. The writer has gone over the west- 
ern slope of the northern part of the Magdalena with a transit 
and has visited almost literally every foot of it. He has also 
made detailed reports on nearly all of the important mines in 
the various camps, often with transit and level work on the 
interiors, so that he is in a position to refer to actual data in re- 
jecting the conclusions offered by Dr. Johnson's critic in some 
respects. It is true that the faulting system is not a pure il- 
lustration of "block faulting," as the writer pointed out in his 
earlier paper in 1897. The faults are not all of the same type 
or of *the same age. They should probably not be called, in a very 
strict sense, "distributive" faults, but the quotation from Dr. 
Johnson's paper, on p. 21 of the article referred to, seems to 
the writer fully justified by the facts. The critic's statement is 
that "some of the principal fault planes bounding some of the 
so-called blocks are not fault planes at all. The phenomenon 
is produced by differential weathering of thick alternating beds 
of hard limestone and soft shale. The back slope slants about 
thirty degrees. Moreover, after going through the mines lower 
down on the mountains, where many minor faults are to be 
noted in the tunnels, the faults were found to be all too insig- 
nificant to even show their presence on the weathered moun- 
tain slope." 
This passage is liable to produce a very misleading im- 
pression. In the first place, the faults, in some cases, have a 
drop of several hundred feet. It is true that in the limited 
sphere of any one mine the work has necessarily been included 
within one of the major blocks. In one case, the entire block 
has been removed, leaving bare granite and quartzyte on a 
large part of the mountain side in what is known as the Jaunita 
gulch. The exposed sides of the remaining blocks show from 
a distance of several miles with the "diagrammatic clearness" of 
which Mr. Johnson writes. To the south, where the major 
faults become nearer to one another, by reason of the radial 
nature of their distribution figured in my earlier article, the 
