MARYLAND GEOLOGICAL SURVEY 127 



general northeast-southwest direction, but aligned to coincide with the 

 general structure of the region. In this same area the zone of cauliflower 

 chert at the base of the Stones River is also well developed, but forms no 

 special topographic features. With weathering, however, the chert breaks 

 up into smaller and smaller fragments so that its presence is not a. 

 detriment to the soil. One of the two western belts lies just west of the 

 Martinsburg shale area and the second is a short belt cut off by faulting 

 in the middle of the state and occupies the center of the western half of 

 the Great Valley. 



Each of these more western belts is quite narrow, because the rocks are 

 steeply inclined. Here too the Middle Stones River cherty limestone is 

 not as clearly developed as in the more eastern areas. Rocks outcrops 

 usually are few, and the formation everywhere gives rise to excellent 

 farm land soil. 



FAUNA OF THE STONES RIVER IN MARYLAND. The fossils of the Stones 

 River limestone in its typical development in the Central Basin of Tennes- 

 see have not received as much attention as those of the younger Ordovician 

 formations, but a considerable fauna from each of its divisions has been 

 collected and awaits description. The faunas of the corresponding rocks in 

 the Champlain Valley have been quite fully described by Raymond in 

 recent years and Middle Chazyan faunas have been recognized farther 

 south in the Appalachians. In Maryland the middle division of the 

 Stones River limestone contains enough Middle Chazy species to make 

 it reasonably certain that these strata represent the same time interval. 

 The massive, purer dove and magnesian limestone of the upper and lower 

 divisions of the Stones River in Pennsylvania and Maryland are not 

 favorable for the occurrence of well-preserved fossils. These two divisions 

 do not weather into chert, and the best specimens from massive limestone 

 are always to be found in the residual cherts. The single-tubed coral, 

 Tetmdium syringoporoides, and the bean-shaped ostracod, Leperditia 

 f abulites, are abundant throughout the Stones River and may be found 

 at almost all exposures. The other seven species here described are all 



