proceedings: geological society 293 



across the broad, open savannas which extend from the Pacific coast to 

 the base of the mountain, where the loads were transferred to the backs 

 of men. At this point the heavy forest begins abruptly and extends 

 upward in unbroken growth, becoming lower, but denser, until on the 

 summit where the rainfall is more copious, orchids and bromeliaceous 

 plants overspread the ground as well as the branches of the trees. In 

 the latter part of May work was carried on at Porto Bello, on the north 

 coast, and by traversing swamps and wading eight or ten miles up the 

 Cascajal River the upper slopes of the Cerro Brujo were reached at 

 about 2000 feet altitude D. E. Lantz, Recording Secretary. 



THE GEOLOGICAL SOCIETY OF WASHINGTON 



The 245th meeting was held at the Cosmos Club, May 10, 1911. 

 As an informal communication Mr. L. D. Burling exhibited specimens 

 of Silurian crinoid stems associated with Pleistocene mollusks collected 

 on the beach north of Chicago. Both are well preserved and afford an 

 example of mechanical mixture of faunas of widely different age. 



REGULAR PROGRAM 



The anorthite-nephelite series. N. L. Bowen. 



The classification of higher grade coals. G. C. Martin. 



On the classification of ore deposits. Waldemar Lindgren. 



At the 246th meeting, May 24, Mr. E. W. Shaw presented two new 

 facts concerning the Maquoketa formation of the Upper Mississippi 

 lead and zinc district: (1) Certain more or less round bits of rock resem- 

 bling concretions with obscure structure and found in a layer near the 

 base of the formation are fossil algal secretions. (2) There is a hereto- 

 fore undescribed angular unconformity between the Ordovician and 

 Silurian at the top of the Maquoketa shale, and a non-fossiliferous rock* 

 which has been considered to be Maquoketa is in reality Silurian resting 

 upon the thin parts of the Maquoketa. The Marquoketa, instead of 

 being 200 feet thick as stated in published reports, varies from 180 to less 

 than 100 feet. At the base of the non-fossiliferous rock and resting upon 

 the deeply eroded Maquoketa is a thin layer appearing to be laminated 

 sandstone but made up of grains of dolomite. 



By invitation of the Council Prof. John C. Merriam of the University 

 of California spoke on recent progress in the correlation of the Tertiary 

 lacustrine deposits of the Pacific coast and Great Basin regions. 



regular program 



Phosphate deposits of the United States. F. B. Van Horn. 

 There are at present five producing phosphate fields of the United 

 States. In the order of quantity of production they are: 



