274 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



other, and <:ool<)<zists are evorvwlioi-e c'ooperatiri<r with those whose 

 work is coniKH-ted with the discovery or exploitation of the mineral 

 wealth of the earth-crust. 



MATEUIAL SERVICE 



Coal. — The first branch of indiistrj' to which geology made itself 

 indispensable was coal mining. Geology has long been in close con- 

 tact with its ])rohloms. in mapping the extent of coal fields, collecting 

 infoiiiKition as to the succession of measures and the existence and lie 

 among them of wants, faults, and igneous rocks, tracing the exten- 

 sion and variation of coal -seams, and estimating the resources avail- 

 abh^; and, as seams are worked at increasing depths, and in those 

 parts of fields concealed under thick unconformable cover of more 

 i-ecent formations, the work of the geologist has become more essen- 

 tial and increasingly productive. 



Tt is interesting to observe the application of the "academic" 

 sides of geoh)gy to these more recondite problems, in unravelling 

 tectonic complexes, in the collection of facts which may eventually 

 elucidate the precise conditions under which different varieties of 

 coal have originated, in applying knowledge as to the limits of the 

 original areas of coal deposit, in the interpretation of stratification 

 in the light of progressive travel of coal-forming conditions geo- 

 graphically across the coal-producing areas, and in the stratigraphi- 

 cal relationship and exact mode of formation of the covering rock 

 s}' stems. 



It is true that the accessibility of coals Avlien first exploited, and 

 their distribution in seams of varying quality, led, and in the newer 

 areas are still leading to much waste; waste on fruitless search in 

 the light of obtainable knowledge, in exploitation of good, thick, 

 and easily worked seams to the neglect of poorer ones, in the non- 

 preservation of satisfactory plans and the consequent leaving of 

 derelict areas, in unsatisfactory drainage, and in the loss of valuable 

 by-products. V>\\i there is a corresponding advantage to those of our 

 generation that some exposed areas of complicated structure, 

 and many of the concealed coal fields were left for ourselves and 

 future generations by reason of Avorking difficulties which it would 

 have been premature to face in the time of easily obtained abundance. 



Even to-day, in spite of improved technical knowledge, there re- 

 main many areas in which information and inference are both scanty, 

 and where difficulties met in working have not yet been surmounted, 

 while there will be in the future ample scope for improved methods 

 and inventions to deal with coal at greater depths than those at 

 wliich it can at jDresent be economically worked. There is room for 

 much new and more precise study than has yet been devoted to the 



