14 FOSSIL MEDUS 4. 
nodules Owing to the folding and fracturing of the strata, it is impossi- 
ble to prove that the sandstones, siliceous nodules, and caleareo-siliceous 
nodules were deposited at the same identical horizon or formed in the same 
period of time This is probable, but in the absence of an unbroken 
stratum and a similar fauna it can not be proved. 
The shale is hard and compact in its unweathered portions. 
CHEMICAL CHARACTER OF THE NODULES AND SHALE. 
Partial analyses, by Dr. H. M. Stokes, of the Geological Survey, of 
the dark inner portion and the red outer portion of one of the fossil medusz 
(nodules) give the following results: 
Analyses of portions of a fossil medusa. 
Dark inner Red outer 
portion. portion. 
WOR caSooooscmeasaces 88. 33 85.13 
AL On casacicemceessee 4, 45 5.15 
Fe,0; sas a/nnwens occees trace By 
(CHOND eésccedcoosesos a3. 91 563.40 
96. 69 
a Pure CO, 1.72. b Pure CO, 1.50. 
The following analysis of the shale, by Dr. Stokes, shows that the mud 
or sediment in which the medusze were buried was highly siliceous: 
Analysis of the Coosa shale. 
Per cent. Per cent. 
SIO Mate ees ascac cece ewe 55. 02 StO\2205:.-225.c2ccceeoeeee trace 
Mi Ogres seer tes =m on S cess . 65 CaQ encase Sea es es ceeeeee 1.60 
PiQiveseeees cameos 06 MgO) o.2escscsce ce siecseees 2.32 
COpsassceete ss oedcseues -83 Ke Osos. cece est cencsenee 3.19 
SOs Soassse ah eee sore ete 02 Naz O reseeccst ockarecaeeee .81 
(C1 De eet ee ARC eeSCe| trace ViisOiss.coseecectcr ceases 03 
AL Ogre cegcammceee ee aes 21. 02 Carbonaceous matter. --... | b.32 
0:8 O Pane eee es Saeco 5 H:0 below 110° .......... 2.44 
LO peas cpspceuosticcetent|| a1.54 H20 above 110° ......-...- | 05.65 
Mn) 25s 5-c nae epee trace 100. 54 
Baws cseeance eee 04 
a FeO approximate only, owing to presence of organic matter. 
b Represents only the carbon of the organic matter. 
¢ Includes water from oxidation of organic matter. 
