438 RECORDS 



» 

 lation Bertrand and Renaud mainly attribute the formations of 

 these coals, are exceedingly delicate and often mucilaginous. 

 Those oi spliagnuni are much thicker, solid and woody, and yet 

 a large quantity of this is required to produce much deposit of 

 carbonaceous matter in swamps. 



The chairman inquired whether freezing or the introduction 

 of silty waters might cause the precipitation of ulmic acid re- 

 ferred to by these authors. Professor Stevenson stated that 

 ulmic acid so precipitated would tend to carry down suspended 

 matters and to clear the waters. 



Dr. Ries stated that while in the Yosemite Valley in Septem- 

 ber, 1899, his attention was attracted by a black, coaly looking 

 mineral in the pegmatite veins on the northwestern side of the 

 valley. On closer inspection the mineral proved to be allanite, 

 and as it has not yet been recorded from this region, it seems 

 of interest to note the fact. 



The rocks forming the walls of the Yosemite are a grano- 

 diorite, according to Turner (17th Ann. Rep. U. S. G. S., Pt. I, 

 p. 710). Traversing this in many directions are veins of peg- 

 matite, which are sometimes straight and unbroken, at others 

 curved, branched, or even broken into. These pegmatite veins 

 are very prominent on the face of El Capitan and also in the rock 

 forming Eagle Peak. It was in the talus at the foot of the lat- 

 ter that the allanite was found, and while the mineral was at 

 times abundant in the pegmatite blocks, still none of it was 

 noticed in the grano-diorite. In only one instance was a dis- 

 tinctly bounded individual found, and on this a combination of 

 orthopinacoid and base were recognizable. The other speci- 

 mens were irregularly bounded grains that varied from a six- 

 teenth to a quarter of an inch in diameter. 



In addition to the quartz, muscovite and orthoclase present 

 in the pegmatite, there were a number of radiating masses of 

 epidote, which were evidently of primary origin ; but in two in- 

 stances the epidote occurred as a coating on hornblende and 

 then seemed to be secondary. None was found in association 

 with the allanite. 



In conclusion it may be said that it is interesting to find that 



