//. G. Hanks — FLanksite in California. 63 



r (IV.) Conclusions. 



The red rock on Pigeon Point is not an altered gabbro nor 

 an altered sedimentary rock, but is the result of the solidifi- 

 cation of a magma, which under certain conditions gave rise 

 to a rock with the characteristics of a granophyre. These two 

 rocks contain a sodium-potassium feldspar, and thus should be 

 classed among the quartz-keratophyres. 



UpGn the contact of the quartz-keratophyre with an olivine- 

 gabbro is a series of rocks, which possess a composition inter- 

 mediate between those of the keratophyre and the gabbro. 

 They may be regarded as the result of contact action at great 

 depths 



Irving's augite-syenites are similar to the Pigeon Point 

 quartz-keratophyre, in some instances, and in others are like 

 the intermediate rocks. They are neither altered gabbros nor 

 altered forms of a previously existing augite-syenite. 



Geological Laboratory of Colby University, June 25, 1888. 



Art. YIL — On the ocmirrence of Hanksite in California / by 

 Henry Gr. Hanks. 



The best known locality of hanksite in California is Borax 

 Lake, owned by the San Bernardino Borax Company. This 

 lake lies in township twenty-five South, range forty three East, 

 Mount Diablo base and meridian, and in the northwest corner 

 of San Bernardino county, the largest in the state, very near 

 the Inyo county line. This vast deposit of soluble salts was 

 discovered and located February 14, 1873, by Dennis Searles 

 and E. M. Shillings. Up to the present time it has produced 

 10,500 tons of borax, and is still far from being exhausted. 

 When the state becomes more populous, and facilities for 

 cheaper transportation multiply, other minerals will also be ex- 

 tracted, to the benefit of those interested, as well as to the State. 



The so-called "Dry Lake," "Alkali Flat" or "Salt 

 Marsh," is a pan-like depression in the desert, ten miles long 

 and five wide more or less. It is the sink of a wide spread 

 water shed and a small stream which heads some fifty miles 

 south. It is the opinion of those who have long resided at or 

 near the locality, that it is a secondary sink of Owens Valley 

 and is partly fed by seepage from Owens and Little Lakes. 

 The climate is generally very dry, but during some seasons, 

 considerable water finds its way to this depression. Having 

 no outlet, the water spreads out and forms a shallow lake or 

 marsh. In the dry season the surface is covered with an alka- 

 line incrustation, which is principally common salt. On the 



