346 The American Geologist. December, 1894 
together with all the surveyed lands in the Dubuque district," 
and that a report thereon was required "before the approach- 
ing winter should set in."* Here Dr. Locke was entrusted 
with the "physical department" of the survey, as noted by 
himself, which he understood to include, especially, the baro- 
metrical observations, the measured altitudes and the geolog- 
ical sections. The report rendered by himf has the following 
parts : 
1. A comparison between the rocks of the lead or mineral region and 
those of Ohio, Indiana and Kentucky, called the "Cliff limestone," 
showing their probable identity. 
2. Several sections of strata (the bight and thickness being deter- 
mined by the barometer) with drawings. 
3. The altitudes of table lands, hills, mounds and mountains, deter- 
mined by barometrical observations, with a chart. 
4. The result of numerous observations and calculations on the ele- 
ments of terrestrial magnetism, including the dip, declination and force 
or intensity of the magnetic needle at several places between Cincinnati 
and the region surveyed, and in that region itself, accompanied by two 
charts: together with some remarks on the practical uses of these ele- 
ments of magnetism. 
5. Surveys of a few of the earthwork antiquities of Wisconsin, with 
drawings. 
6. Some observations on the climate and meteorology of the upper 
Mississippi. 
1. Acknowledgments and concluding remarks. 
The lead-bearing limestone of the upper Mississippi valley 
he considered older than the coal-bearing rocks, arguing at 
some length to prove that Keating's idea of their super-Car- 
boniferous position was erroneous, and that they were the 
equivalent of the Cliif limestone of Ohio. He gives colored 
sections from the south fork of the Little Maquoketa to Sin- 
sinewa mound, and across the Mississippi at Prairie du Chien. 
The former shows only the Cliff limestone, 550 feet in thick- 
ness, abounding in veins of lead ore, and the Blue limestone 
somewhat below water-level. The latter represents the Blue 
limestone about 400 feet above the river, 115 feet thick, un- 
derlain by the Butt' limestone 20 feet thick, which rests on a 
soft sugar-like sandstone 40 feet thick. Magnesian linie- 
*Keport of Dr. Owen dated Jan. 20, 1840. 
fReport of John Locke. M. D., to David Dale Owen, M. D., principal 
agenl to explore the mineral lands of the United States. Included 
in Dr. Owen's report ordered to be printed by the Senate June 11. 1844. 
This report was also printed by order of the House, in 1845. 
