906 



SCIENCE 



[N. S. Vol. XXXIII. No. 858 



Ten years ago I began systematic study of con- 

 ditions throughout the vast Appalachian basin, 

 hoping to find there enough information for solu- 

 tion of the problem involved; but the results vpere 

 far from sufficient and study of other regions 

 became necessary. This required examination of 

 hundreds of publications, large and small — and 

 the examination is still far from complete, for the 

 literature, to speak moderately, is sufficiently ex- 

 tensive and, within the last quarter century, suffi- 

 ciently intensive. While plodding through it, I 

 discovered that much of what has been regarded 

 as new in later days is really very old. The work 

 of earlier students, buried in publications of 

 learned societies, has passed into oblivion. In 

 some instances, important observations have been 

 recorded incidentally in discussion of other topics. 

 Often, the work of an investigator is known only 

 through citations, which, separated from their 

 context, are apt to give a wrong conception of the 

 author's opinions. As the examination advanced, 

 I became convinced that it would be well to pre- 

 sent, without comment, a synopsis of each work 

 that seemed to have aa important bearing on the 

 subject, that the development of opinion might 

 be made clear and that proper credit might be 

 assigned to men who did excellent work with 

 meager opportunity. Such a presentation seemed 

 also likely to serve as a proper foundation for the 

 general discussion and it is ofCered here as the 

 first part of a monograph upon the formation of 

 coal beds. 



As the study advanced, the elements of the 

 problem were found to be more numerous and 

 more complicated than had been supposed. It has 

 become essential to consider in detail some sub- 

 jects of which many of the disputants on both 

 sides appear to have very indefinite conceptions. 



The second part of the monograph wOl consider 

 the flexibility of the earth's crust as illustrated 

 in the history of North America; the phenomena 

 of rain and floods; the features of swamps and 

 marshes; the buried forests of modern and an- 

 cient times; with other topics of similar import. 



The third part will consider the various de- 

 posits of the Coal Measures, sandstones, shales, 

 limestones and coals; the effort will be made to 

 determine the sources and the mode of distribu- 

 tion of the inorganic materials; the origin of the 

 coal and the causes of its variation in character; 

 its mode of occurrence and the structure of coal 

 beds. 



The fourth part will sum up the results in an 



effort to show their bearing on the solution of the 

 problem. 



Proilems in Petrology: J. P. Iddings, U. S. Geo- 

 logical Survey. (Introduced by President 

 Keen.) 



Front Sange of the EocT^y Mountains in Colo- 

 rado: W. M. Davis, of Harvard College. 

 The Front Kange of the Eocky Mountains in 

 Colorado, now easily accessible by various rail- 

 road lines which enter and cross it from Denver 

 and Colorado Springs, is an unusually fine ex- 

 ample of a mountain highland, which in a former 

 cycle of erosion was reduced to moderate relief, 

 and which since elevation to its present altitude 

 has been submaturely dissected by its streams. 

 The highland is surmounted by numerous hills 

 and mountains of from 500 to 2,500 feet relief, 

 which represent the unconsumed residuals of the 

 former cycle of erosion, and which, therefore, pre- 

 sumably consist of the most resistant rocks of the 

 region. The uplift of the mountain belt to its 

 present altitude was not perfectly uniform, but 

 arched gently from the plains westward; thus the 

 crest of the range seems to correspond to the 

 crest of the arched uplift. A notable feature of 

 the higher valley heads, among the surmounting 

 mountains near the range crest, is the occurrence 

 of numerous amphitheaters or cirques, and over- 

 deepened valley troughs, the work of glaciers 

 which for a moderate time, as geological time is 

 reckoned, replaced the water streams in the high- 

 est districts. The contrast between forms due to 

 ordinary or normal erosional processes and to 

 glacial erosion is thus displayed with unusual 

 clearness. 



Supposed Secent Subsidence of the Atlantic 

 Coast: D. W. Johnson, of Harvard College. 

 (Introduced by W. M. Morris.) 

 The author briefly reviewed the evidence in 

 support of the generally accepted theory that the 

 Atlantic Coast is subsiding at the rate of from 

 one to two feet per century, and showed that the 

 phenomena supposed to indicate subsidence might 

 be produced by fluctuations in the height of ordi- 

 nary high tides resulting from changes in the 

 form of the shore line. A study of the Atlantic 

 shore line indicates that conditions are there fa- 

 vorable to marked local changes in the height of 

 the tides, mdepeudently of any general movement 

 of the land. On the other hand, the structure of 

 certain beaches along the coast affords very 

 strong proof that there can have been no long- 

 continued progressive subsidence of the coast 



