Penrose.] FHOSPHATES OF RUSSIA. 113 
siliceous matter. There are usually from oue to three of these separate 
beds and sometimes as many as seven. Their thickness varies from 6 
to 20 inches. 
The following sections by Dr. C. U. Shepard, jr., will show the posi- 
tion of the phosphate beds : 
Section 1. In the township of Briansk, government of Orel, on the banks of the 
Desna, the . ssamorod occurs in large flat pieces, 3 to 4 feet square and 10 inches 
thick. 
The order of occurrence is as follows : 
(1) Argillaceous marl. 
(2) White chalk. 
(3) Siliceous marl, with thin layers of chalk and small nodules of phosphate of lime 
\\ feet thick. 
(4) Ssamorod occurring (as above described) in flat slabs. 
(5) White sand 2 feet thick. 
(6) Second deposit of ssamorod, in nodules; 8 inches thick. 
(7) Brown sand over 5 feet thick. 
The upper deposit of phosphate slabs consists of hard brown nodules, cemented to- 
gether by siliceous and calcareous matter. The lower layers are dark green and soft 
when first dug. 
Section 2. The same slabs also occur in the neighborhood of Kursk and towards 
Orel. At Dmitrovsk the occurrence is as follows : 
(1) Red clay, 7 feet thick. 
(2) White, calcareous marl, containing many small, phosphatic nodules, 4 feet thick. 
(3) Very small nodules of phosphate cemented by calcareous matter, 14 inches thick. 
(4) Thin layer of brown quartz sand with small nodules. 
(5) Phosphatic slabs, 10 inches thick. 
These slabs are not flat on the upper side, but irregular and kidney-formed. The 
size of the slabs varies considerably ; some are as large as 3 feet long by 2 wide. 
Section 3. The occurrence at Jablovsk is as follows : 
(1) Soil and earth. 
(2) Marl, a few feet in thickness. 
(3) Chalk, a few feet in thickness. 
(4) Siliceous marl, with fine grains and pebbles of phosphate, 1 to 2 feet thick. 
(5) Sand a few inches thick. 
(6) Phosphate rock. 
Here the rock comes to sight on the sides of water-worn gullies in the rolling 
country. 1 
The phosphate stratum underlies an immense extent of country, but 
it is often at such an inaccessible depth, that most of it is of but little 
practical value, and it can only be profitably mined where it crops out in 
the ravines. Besides their inaccessibility, the nodules are of poor 
quality, varying, as they do, in their content of phosphoric acid from 
12 to 35 per cent., and averaging only 20 per cent. 2 The nodules are 
very siliceous, the grains of sand being plainly visible in them. In this 
respect they very much resemble the North Carolina Tertiary phos- 
phates. 
l Dr. C. U. Shepard, jr., MSS. 
2 Alex. Yermoloff, Jour, agric. pratique vol. 1, 1872. 
Bull. 46- — 8 (587) 
