American Association Meeting. 251 
7. The Middle Coal Measures of the Western Interior Coal Field. 
By H. Foster Bain and A. T. Leonard, Des Moines. Iowa. 
The lower coal measures of the western interior coal field are marked 
by non-persistence of strata. The upper measures are more regular. 
Between the two is a series partaking of some of the characteristics 
of each. This series includes the Raccoon River beds, the Appanoose 
formation and equivalents in Iowa; the Henrietta in Missouri; and 
the Oswego and Pawnee limestones of Kansas. No fitting general 
term for the whole has yet been proposed. The old term, middle 
coal measures, included the beds here referred to and the higher beds 
now quite generally known as the Pleasanton shales. 
8. The Principal Missourian Section. By Charles R. Keyes, 
Ces Moines. Iowa. The previous classifications of the Carboni.'erous 
formations of the region west of the Mississippi river were briefly out- 
lined. The results of the recent work along the Missouri river were 
summarized, and the inferences to be drawn were given. The Mis- 
sourian series, as one of the four principal subdivisions of the Car- 
boniferous of the continental interior, was described. Eleven well de- 
fined formations or stages are shown to have a wide distribution, the 
lormatiors in five states being correlated. 
9. Tourmaline and Tourmaline Schists from Belcher Hill, Jeft'er- 
son County, Colorado. By Horace B. Patton, Golden, Colo. 
Black tourmaline, often in fine large crystals, occurs very abundantly 
in pegmatite veins that cut the crystalline schists of the foot-hills of 
Jefiferson county, west of Denver, Colorado. On the Belcher Hill 
road near Golden the tourmaline occurs (a) in separate crystals; (b) 
in black masses (schorl) in quartz veins; (c) the same in pegmatite 
veins; and (d) in finely disseminated needles replacing biotite and 
even feldspar and quartz in biotite schists and gneisses at contact with 
veins of pegmatite and quartz. The beautiful banding and cross-band- 
ing produced by this replacement is unusual. The paper was illus- 
trated by specimens and photographs. 
10. Magmatic Dififerentiation in the Rocks of the Copper-bearing 
Series. By Alfred C. Lane, Houghton, Mich. In many of the 
effusive sheets a difference may be noted between the top and the 
bottom. At the top the feldspar is oligcclase, at the bottom labra- 
dorite. At the top olivine is more conspicuous, at the bottom auo^ite. 
The oligoclase and olivine were evidently formed before the lava from 
which the sheet was formed came to rest, at least in part. The 
augite and labradorite were probably formed later. It is possible that 
the early formed oligoclase rose to the top, and that the sodiferous 
magma there formed had not so corrosive action on the olivine as the 
calcareous magma left below, which latter may have corroded the 
olivine and out of it formed augite. Comparing different flows, we 
find the same kind of relations that exist between the top and bot- 
tom of the same flow. This suggests that similar differentiation went 
on before eruption. 
