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Vol. XVI, No. I, p. 228. pl. Ill, figs. 13-14. 
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LAWS OF FORMATION OF NEW MEXICO 
MOUNTAIN RANGES. 
By C. L. Hbrkick, Socorro, New Mexico. 
PLATES XVI— XVII. 
The writer has been engaged at intervals during the past ten 
years in collecting materials for a study of New Mexico moun- 
tain structure and, during part of this time, was engaged in 
practical mining operations in the M'agdalena mountains. He 
hopes, therefore, that he may be permitted to point out what ap- 
pear to be inaccuracies of a somewhat misleading nature in 
the paper printed in the American Geologist for January, 
1904, under the caption, "Notes on Block Mountains in New 
Mexico." 
In the general question at issue between Dr. Johnson and 
the writer of the article named the writer has no interest at 
the present time, and he certainly holds no brief for "block 
mountains," a term which needs to be quite loosely defined to be 
applicable at all to New Mexico mountains: In the discussion 
of this type of mountain structure much will depend on the 
definition of what are called "distributive faults." 
When, however, the conditions in the Magdalenas are said 
to be "identically the same as in the Sandias, except that the 
fault scarp faces east instead of west, and there is no reason to 
suppose that there is more than a single great drop" we must 
demur. Still more impossible is it to include in one category 
the above mentioned with the Sierra Ladrones. the Manzano 
range, Sierra Oscura, San Andre (a) s, Franklin range. Sierra 
