MISSOURI 665 prairies afford excellent pasturage, and where they are grazed down a fine growth of blue grass takes the place of the original wild grass. The geological formations include the coal measures, 1,950 ft.; lower carboniferous, inclu- ding Chester group, 300 ft. ; ferruginous sand- stone, 100 ft. ; St. Louis limestone, 250 ft, ; Keokuk group, 200 ft. ; Burlington group, 300 ft. ; and Chouteau group, 230 ft. The Devo- nian is represented by the Hamilton and On- ondaga, 100 ft. ; the upper Silurian by the Oriskany, 30 ft., Delthyris shale, 350 ft., Ni- agara group, 225 ft., and Cape Girardeau lime- stone, 50 ft. The lower Silurian includes the Cincinnati group, 100 ft., Trenton and Black river limestone, 400 ft., and magnesian lime- stone series, about 1,500 ft. ; the latter includes 300 to 400 ft. of sandstone excellent for glass making. The southern part of Missouri, in- cluding the Ozark ridge and most of the state S. of the Missouri and Osage rivers, except- ing the two western tiers of counties, is from 1,000 to 1,400 ft. above the sea, and includes lower Silurian rocks, flanked by lower carbon- iferous. On the W. flank, near the state line, the country is not often over 800 ft. above the sea. On the W. and N. flank of this high- land the coal measures commence. On the S. side of the Missouri river are found the middle and lower coal, not over 800 or 900 ft. above the sea. In N. Missouri the same formations are about 800 to 1,000 ft. above the sea. The elevation of the eastern and southern outcrop of the upper coal measures, near the base, is 875 to 990 ft. Toward the northern part of the state the upper measures are more elevated, and may reach from 1,000 to 1.100 ft. above the sea. The coal measures being composed of alternations of shales, sandstones, and lime- stones, their topography is such as would re- sult from decomposition of such rocks. In no place has any limestone been observed of greater thickness than 30 ft., and the sand- stones often pass into shales ; so the topography of the coal formations is nowhere very rugged. Along the line of outcrop of the limestones are sometimes seen steep and rugged hillsides, occurring from Cass county on the south, through Jackson, Platte, Clay, Eay, Caldwell, Daviess, Gentry, Worth, and Harrison counties. N. and "W. of this are the upper measures, in- cluding alternations of thick and thin strata of limestone, with sandstones, shales, and clays ; the resultant being the undulating and roll- ing portion of N. W. Missouri. The Missouri bluffs, in the region of the upper coal measures, attain an elevation of 250 to 330 ft. above the Missouri bottoms, and the inland ridges are but little higher. The summits of the highest ridges in Nodaway county, above One Hun- dred and Two and Platte rivers, are but little over 200 ft., and the bluffs along the streams are in no place over 50 ft. high. On North Grand river the immediate bluffs measure from 30 to 120 ft. within the upper coal district. Lower down stream, in the middle and lower coal regions, the hills recede and become lower. Near the base of the upper coal series, it is often 200 to 250 ft. from the valleys to the top of remote ridges. In the lower and middle coal measures are great thicknesses of sand- stones and shales, and long gentle slopes are found with bluffs on the streams 25 to 50 ft. high, rising to 100 ft. at a half mile to a mile. When the middle coal measures approach the Missouri river its bluffs vary in height from 100 to 165 ft. Another important character- istic is peculiar, especially near the junction of the upper and middle coal measures, and sometimes to the lower measures. The sand- stones are very much denuded, leaving isolated mounds generally 80 to 100 and sometimes 140 ft. high, rising by very long slopes above the lower plains. These mounds are generally capped with limestone, which has preserved them from entire destruction. They are com- mon throughout the lower coal district of S. W. Missouri, with sometimes intervening val- leys 10 to 15 m. wide. The mounds have a circular base, sometimes elongated N. and S. This is particularly observable in a range trending S. along the W. line of Bates, Ver- non, and Barton counties. From a distance these mounds appear like low mountain ranges. Aside from the mounds, the surface of the country is gently undulating and rolling. The Missouri coal field comprises an area of about 23,100 sq. m., including 160 sq. m. in St. Louis county, 8 in St. Charles, a few outliers in Lin- coln and Warren, the remainder in N., W., and S. W. Missouri. In this area are included 8,400 sq. m. of upper or barren measures, 2,000 of exposed middle, and 12,700 of exposed lower measures. The southern and eastern boundary of the lower coal measures is as fol- lows: entering the state about midway the west line of Jasper county, thence extending northeastwardly through Jasper, Barton, Bade, Cedar, St. Clair, Henry, Benton, Pettis, Saline, Howard, Boone, Callaway, Audrain, Mont- gomery, Rails, Monroe, Shelby, Knox, Lewis, and Clark counties. The aggregate thickness of the upper coal measures is 1,317 ft., inclu- ding only about 4 ft. of coal, in which are two seams 1 ft. thick, with lesser streaks. The middle coal measures include a total thickness of about 324 ft., in which are embraced about 8 ft. of coal, including two workable seams of 21 and 24 in., one which varies from 1 ft. to 3 ft., and six seams too thin to work. The lower measures include from 250 to 300 ft., embracing about five workable seams of coal, varying in thickness from 1 to 4 ft., and thin seams from 6 to 11 in. thick, with lesser seams and streaks; in all, 13 ft. of coal. Missouri has therefore nearly 2,000 ft. of coal measures, with a total aggregate of 24 ft. 6 in. of coal. All beds over 18 in. thick are estima- ted as workable. The estimated area, where such may be reached within 200 ft. from the surface, is about 7,000 sq. m. The drift for- mation spreads over the whole of N. Missouri,
