The Galena and Maquoketa Series. — Sardeson. 36f3 
UPPER BLUE LIMESTONE. 
Green rock, J. D. Whitney, (1861). Geology of Wisconsin, vol. i, p. 
252, plate vi. 
Upper Blue beds, T. C. Chamberlin, (1877). Geology of Wisconsin, 
vol. II, p. 296. 
" Green rock," T. C. Chamberlin, (188.3). Geology of Wisconsin, vol. 
IV, p. 412. 
Upper Blue limestone. T. C. Chamberlin, (1883). Geology of Wis- 
consin, vol. I, p. 163. 
A dirt'erent division of Trenton was used in the Minnesota 
Geological Survey reports. For example, tile strata compris- 
ing tlie " Trenton " or Beloit formation were divided into two 
nearly equal parts, and the lower half, containing the Butf 
limestone and part of the Lower Blue limestone, were called 
the Lower Trenton Limestone, the remainder of the forma- 
tion, Green Shales. These, with the Upper Trenton Limestone 
and sometimes a division called Galena Limestone, make up 
the Galena-Trenton series. 
Later the term Trenton limestone was used instead of Low- 
er Trenton, and a division of Trenton Shales was made to in- 
clude the Green Shales and part of the true Galena. 
LOWER TRENTON LIMESTONE OR TRENTON LIMESTONE. 
Lower Trenton limestone, N. H. Winchell, (1876). Geological and 
Natural History Survey of Minnesota, 4th Annual Report, p. 42. 
Lower Trenton limestone, N. H. Winchell, (1877). Geological and 
Natural History Survey of Minnesota, 5th Annual Report, pp. 147, 148. 
Trenton limestone, N. H. Winchell, (1888). Geological and Natural 
History Survey of Minnesota, Final Report, vol. ii, pp. 10 (39), 70, 288, 
356, 388. 
Trenton limestone beds, C. W. Hall, (1889). Bulletin Minnesota 
Academy of Natural Sciences, vol. iii. No. 1, p. 113. 
GREEN SHALES. 
Green Shales, N. H. Winchell, (1876). Geological and Natural His- 
tory Survey of Minnesota, 4th Annual Report, p. 42. 
Green Shales, N. H. Winchell, (1877). Geological and Natural His- 
tory Survey of Minnesota, 5th Annual Report, p. 147. 
Green Shales, N. H. Winchell (1884). Geological and Natural History 
Survey of Minnesota, Final Report, vol. i, p. 218. (Hudson River 
Shales), 293, 3.34. 
Green Shales, N. H. Winchell (1888). Geological and Natural History 
Survey of Minnesota, Final Report, vol. ii, p. 40. 
TRENTON SHALES. 
Trenton shales, E. O. Ulrich (1883). Geological and Natural History 
Survey of Minnesota, 14th Annual Report, p. 57. 
