io8 The American Geologist. February, 1903. 
enough to establish the age of these lava flows in Post-Ter- 
tiary times, between the close of the Pliocene and the refilling 
of the Jemez tpough with the Pleistocene deposits. Their age 
is late-Tertiary and early-Pleistocene. 
Economics. 
Climate. — The altitude of this region, 5000 to 9000 feet 
above the sea, and its latitude, 35 to 36 degrees north, combine 
to give it a climate which for mildness and equality has no 
superior in the world. Its location near the center of the vast 
rainless region of the west, and its remoteness from any large 
body of water, give it an atmosphere almost totally devoid of 
moisture. The annual precipitation is less than eight inches. At 
the same time, by reason of the latitude and altitude the air is 
both warm and light, thus furnishing, in unlimited quantities, 
nature's remedy for diseases of the lungs. 
Soil. — The soil on the table lands especially on the Tertiary 
formations, is poor. There is too much alkali. But if water 
for irrigating purposes could be had, even the soil of these 
mesas, in a few years, could be made productive. It would 
require considerable labor and the use of fertilizers such as 
gypsum, burned lime, etc., but in the end it would yield profit- 
able results. 
On the mountain plateau the soil is good, especially in the 
Jemez mountains, in the Valle Grande country. This great 
valley occupies a high altitude, averaging 9000 feet. It em- 
braces 100,000 acres and forms fine prairies with abundant 
grasses. On it also the fir and pine are most magnificently 
developed. This place is cool, and to it people go for an out- 
ing in summer. Here dews fall almost every night in the 
year. 
Physical Conditions of the Soil:'^^ 
Fine and coarse sand 87.95 
Fine silt and clay 12.05 
Hydrascopic moisture 1.35 
Chemical bound water and organic matter . . 3.63 
Chemical Constituents of the Soil: 
Potassa 074 
Soda on 
Lime 152 
♦ Magnesia trace 
Sulphuric acid trace 
