120 
Transactions Texas Academy of Science. 
.Gregg, A. 
occur in the southern part of the County, Pure white clean sand suitable 
for glass is found in the western part of the county. Coal found at Mil- 
burn (McCulloch County) and Vicinity. 
‘‘The so-called mineral belt extends through the southern third of the 
county, and in it have been found gold, silver, copper, lead, and manga- 
nese, but none of these minerals have as yet been mined with success.” 
P. 76. 
176. Gulliver, F. P. 
Cuspidate Forelands. 
Bulletin Geol. Soc. Amer., A^ol. YII^ pp. 399-442. 1896. 
Among the typical examples of “Overlap,” that at Corpus Christi Pass, 
Texas, is mentioned. 
177. Harrington, H. H. 
Alkali 'Soils. 
Geological and Scientific Bulletin, Vol. I, No. 12. Houston, 
April, 1889. 
“ ‘Alkali soil,’ as the term is commonly employed, lias reference usually 
to the saline or alkaline matter present in the soil that exerts an injurious 
effect on vegetation. These salts may or may not be really alkaline in 
reaction. The term ‘alkali aoil’ is, therefore, to a certain extent, indefinite 
and ambiguous, since the salts may consist of borates and carbonates of 
potash and soda, giving an alkaline reaction to' test paper, viz. : Chlorides 
and sulphates of potash, soda and magnesia, phosphates of soda and lime, 
nitrates of soda and potash. It will be at once noticed that the latter 
elaSiS of compounds contains the three great elements of plant food — 
potash, phosphoric acid and nitrogen — ^those three elements which alone 
the agriculturist can afford to buy in a fertilizer, and upon which every 
eommeroial fertilizer depends for its value. 4 call special attention to 
this fact, because, when the alkaline soils of (Western Texas are brought 
under cultivation, the practically inexhaustible quantity of some of these 
ingredients will be a matter of great economical importance, enabling the 
farmer, by a judicious use or renewing of organic matter in the soil, to 
possess a farm that Avill enrich both father and son. 
“From a preliminary investigation of Pecos Valley soils, it seems that 
their alkalinity is due chiefly to alkaline carbonates of potash and soda 
and ehlor'ides of the same elements. The first two salts are by far more 
injurious to plant gro'VAdh, particularly blighting the young blades as they 
emerge from the ground, dn some respects, however, their presence is not 
to be so much deprecated as is the presence of the chlorides, either alone 
or mixed with sulphates, since the alkaline carbonates, unless present in 
large quantity, may be decomposed by gypsum or sulphate of lime, con- 
verting the lime sulphate into the beneficial carbonate and the alkaline 
carbonates into the neutral sulphates. The chlorides, on the contrary, and 
some of the sulphates, it is necessary to remove by irrigation and drain- 
age, unless, indeed, the quantity of rain were sufficient to carry these salts 
below the surface to an underground channel, or along the surface to 
