552 E. J. Garwood and J. E. Marr — On Carboniferous Zones. 



The reason for the existence of P, latissimus at what is apparently 

 a constant!}' higher horizon as compared with the Lower Scar 

 Limestone, as we proceed northward, we hope to discuss elsewhere; 

 at present we wish to call attention to the fact that, whatever the 

 lithological characters of the strata, the beds with P. latissimus occur 

 definitely above those with P. giganteus. 



The writers hope to obtain further information concerning the 

 minor subdivisions of the Carboniferous rocks of the Northern 

 Pennine region, and in the meantime would urge observers to 

 study the distribution of the Carboniferous fossils in other regions. 

 The Southern Pennine Chain, the neighbourhood of the Bristol 

 Coal-field, and the Carboniferous rocks of North and South Wales 

 would probably repay the labour of a minute study ; and local 

 collectors are particularly requested to note the exact horizon of 

 each fossil which they obtain, a task by no means difficult, with the 

 admirable detailed maps of the Geological Survey to serve as a 

 guide. The writers' observations coincide with those of others who 

 have attempted to differentiate minor divisions of the Carboniferous 

 strata, indicating that the Braohiopods are most likely to repay one 

 in carrying out such work ; but the remarkable results which have 

 followed from a careful study of the Ammonites would suggest the 

 desirability of careful collection and examination of the Goniatites, 

 which are pretty abundantly found in most districts. At the same 

 time, other groups of fossils should not be neglected ; corals, 

 especially, will probably yield valuable information in the hands of 

 specialists. 



It is daily becoming more apparent that the Carboniferous period 

 "was not, as some have supposed, a comparatively brief period, 

 throughout which sediment accumulated with exceptional rapidity. 

 The remarkable discovery by Dr. Hinde and Mr. Howard Fox of 

 thick deposits of Radiolarian cherts in Devon, Cornwall, and Somerset, 

 is of particular interest from this point of view. It can hardly be 

 doubted, therefore, that fossil zones, such as have been defined in 

 strata both older and newer, can also be detected in the beds of 

 Carboniferous age ; and if so, it is fully time that the necessary 

 work should be done in strata of such importance. That it has 

 not already been achieved is a probable indication that the task 

 will be a more difficult one than that of separating the Lower 

 Paleozoic or Mesozoic rocks into zones, and may probably be too 

 much for one or two workers. We therefore suggested at the recent 

 meeting of the British Association that a committee might be formed 

 to inquire into the possibility of dividing the Carboniferous strata of 

 Britain into fossil zones; that it should be the duty of the committee 

 to call the attention of local observers to the desirability of collecting 

 Carboniferous fossils, making accurate notes as to the horizon of 

 each, and paying special attention to the Corals, Trilobites, Braohio- 

 pods, and Cephalopods; and that the services of eminent specialists 

 who have studied these groups of fossils should, if possible, be 

 retained by the committee, to study the specimens submitted by 

 the local observers. 



