These methods were accepted as adequate for the construction of a topographic map for the present purposes on the scale and with the contour interval used. More must not, therefore, be demanded of such maps than these considerations warrant, though they will prove of value in the future for many other industrial and scientific uses than those for which they were especially constructed. They portray with exactness the distribution of upland and lowland, and, with reason. able faithfulness, the relative elevations of the various hills. It is not maintained that the exact amount of grading necessary for the construction of a railway across the areas represented on such maps can be calculated from their study; yet, on the other hand, the general question of the practicability of construction along any line can be determined at a glance. In addition to the topographic base, the distribution of the geological formations is clearly shown on the map by the dif ferent colors. The flat shades of gray used for the divisions of the Coal Measures have been adopted after experimentation with various color schemes. It was found that any scheme involving the use of a series of over-printed patterns could not be introduced on maps containing so much other detail as do these, without seriously obscuring the latter. In addition to such general geologic delineation, it will be observed that many outcrops are located on the map. These are generally outcrops of special importance for the correlation of sections. The horizon lines of important coal beds are also introduced. Such a line is shown where there is reason to believe that the particular bed is actually present. Elsewhere it is omitted, to indicate the fact that the existence of the bed is not recognized, even though there is no geologic break between the two areas, and, strictly speaking, the geologic horizon of the coal bed is still present. On the other hand, however, for manifest reasons, no allowance is made in the location of the horizon line for the covering of superficial material. Thus, where the thickness of the latter is great, and the hill slope slight, the actual limits of a coal bed are well within the horizon line shown on the map. This accounts, in cases, for the absence of coal in wells or drill holes within the limits assigned a coal bed. The depth of such superficial material is so variable that it is impossible to predicate just how far within the plotted horizon line the coal terminates at all points. Such details must be settled by observation and prospecting at each locality. This influence of the superficial material must always be considered in interpreting such representation of horizon lines. The report accompanying this map is made as exhaustive as the status of the work of the Survey will permit. It includes the results immediately relating to this area which are published in reports of earlier surveys, in addition to the large amount of data which were collected along with the recent mapping. The more prominent mineral products are described in greater or less fullness, in proportion to their importance. Some of these will be subjects of further investigation in the future, but it was deemed inexpedient to postpone the publication of the sheet report until this supplementary work was completed. The coal analyses were all made by Mr. J. D. Robertson in the Survey laboratory. The samples are originally collected in air-tight fruit jars and are preserved in these. A portion for analysis was taken from such a jar and ground to a powder, and then exposed to the air for a period of about two days to rid it of excessive moisture. The moisture was determined by subsequently heating in an air-bath for one hour, at a temperature of 105° to 110° C. The volatile hydrocarbon was determined by successively heating a fresh portion of the coal in a closed crucible, for 3 minutes over the Bunsen burner and then over the blast lamp; the fixed carbon, by ignition of the remaining carbon or coke in the open crucible. The total sulphur was determined by the Eschka method; the sulphur in the ash by fusion with potassium and sodium carbonates and a little potassium nitrate, solution and precipitation as barium sulphate. As many of these coals contain visibly considerable amounts of selenite, or sulphate of lime, it was thought that this constituent might account for a large part of the total sulphur con tained in Missouri coals. To decide this the determinations of the sulphur in the ash were made. The difference between the total sulphur and the sulphur in the ash is the sulphur which goes off in the combustion of the coal, and may thus be considered the deleterious sulphur in most processes of combustion. The small amounts of sulphur which the analyses show to exist in the ashes make these determinations of less value industrially than was anticipated. Upon the section sheet accompanying the map are drawings prepared from the records of various drill-holes, and in the text are descriptions of others. These records are mostly derived from work with the churn drill, by miners or well-drillers of the county. With some only imperfect notes were preserved, and with few could actual samples of the drillings be examined by the Survey. The results are presented as the best attainable, but are to be accepted with the reservations which attach themselves to all data so derived. The geology of the area was specially studied by the writer, and all important coal openings were visited by him. The field work for the topographic map was done by Mr. Leo Gluck and Mr. C. F. Marbut under the writer's direction; in addition they located the various coal and other outcrops, and collected other notes which have been incorporated in the report. Prof. J. E. Todd made a special study of the Quaternary deposits and prepared the section on that formation, printed herewith. Mr. Gilbert Van Ingen, of the U. S. Geological Survey, made certain observations on the Warrensburg sandstone which are incorporated. |