The Cumberland Gap coal field lies in Bell and Harlan counties, in the southeast corner of Kentucky and in Claiborne and Campbell counties, Tenn., and extends in a general northeast-southwest direction between Pine and Cumberland mountains from Fork Mountain on the southwest to the heads of Poor and Clover forks of Cumberland River on the northeast. As defined in this paper, it has a total length of about 90 miles and a width of from 15 to 20 miles. (See Pl. II.) In this paper is described only the central part of the basin, or the area lying between Log Mountains at the head of Yell ow Creek of Cumberland and nearly north-south line about 10 miles east of Harlan, and while the data presented will give an idea of the general stratigraphy and structure of the whole field, they are not authoritative except within these limits.
Present conditions of production in Pennsylvania and the outlook for the future as regards (1) new drilling oil fields, (2) development of new End_Page 100------------------------------ fields, (3) development of deeper sands and (4) the revival of old fields. (1) will yield much additional oil and hasten depletion of gas, (2) will add little oil but many small gas fields, (3) already well prospected except Oriskany and Medina sands, and (4) much new oil from Bradford and elsewhere. End_of_Article - Last_Page 101------------
GENERAL STATEMENT The numerous problems involved in the scientific classification and nomenclature of rock units have long engaged the attention of geologists. The appended partial list of papers dealing with this subject sufficiently indicates its scope and importance. Gradually, certain guiding principles have come to be recognized generally, and practices deemed good in the classification and nomenclature of rock units have become fairly well established. There is much room, however, for development of the principles and especially for the more widespread application of what seem to be the best practices in using the principles. The larger geological surveys have, necessarily, given consideration to the formulation of rules to provide for their own publications a comparative uniformity in the method of classifying and naming the rock units treated by them. But such rules have not been propounded and widely disseminated with intent to promote their use by geologists in general. . . .
In the preceding paper 2 in.thisseries the attempt was made to ascertain the maximum deposition of the coals of the northern Appalachian coal field, it being held that the time necegsary for the formation of each coal bed must be sufficient to permit the formation of that bed at the point of its greatest thickness.The sum of these maxima gave a total thickness of about 3oo feet for that field.The purpose of obtaining this number was the belief that a study of the maximum rate of deposition of vegetal matter to-day in connection with the known maximum deposition of coal in a selected area might form the basis for estimating the time involved in the process.Without going over the evidence in detail, it is apparent from a comparison given beyond that under the conditions existing to-day, the most rapid accumulations of vegetal matter result from the growth of more or less aquatic plants under certain favorable conditions.Turning, then, to the consideration of the aquatic or semiaquatic plants, we are concerned with the growth or rate of accumulation of the resulting carbonaceous matter.There are a great variety of such plants, varying greatly in their habits of growth.The accumulation of the remains of such plants may be broadly classed as peat beds.Under certain conditions these plants, on dying, undergo only partial decomposition and the gradual accumulation of carbonaceous matter results from the process.Such accumulations are commonly below water level in lakes, ponds, or along the seashore, but under certain favorable conditions of moisture and temperature they may be above water level on gentle slopes.While in some cases such accumu-
