HUGHES : INGLEBOROUGH. 
71 
details made the pioneers of geology concentrate their thoughts 
on those large stratigraphical generaUsations which strike us 
so much in their work. 
In the case of the rocks we are now considering there were 
great masses of more or less sandy mudstone and shale, often 
under local conditions becoming flaggy and generally having 
a good deal of subordinate sandstone or grit intercalated among 
the lower beds, and similar coarse material making up nearly 
the whole of the upper part of the series. These were the Denbigh 
Grits and Flags of North Wales, and the Coniston Flags and 
Grits of our district. 
There were also on a lower horizon in the Bala Beds, great 
masses of sandy mudstone, sometimes becoming flaggy. 
In the Builth district in South Wales also, there were an 
upper series of flags belonging to the Wenlock, and a lower 
series known as the Llandeilo Flags. These were at first con- 
founded together, but were afterwards separated and found 
to be characterised by an entirely different group of fossils. 
The identification of these several series in different areas was 
a question for palaeontology, but until the succession had been 
clearly ascertained in some one area by stratigraphy, the 
palaeontological evidence might be, and indeed was, misleading, 
as we find from the history of one of our most important fossils, 
Cardiola interrupta. 
Salter, who was as good in the field as he was in the museum, 
maintained that there were in Wales two sets of flaggy mudstones, 
an upper belonging to the Silurian, and a lower to the Bala 
Series. This we.s in time clearly made out in the Lake District, 
in North Wales, and in the Builth area in South Whales. The 
Coniston Flags at first included everything down to the bottom 
of the Austwick beds. The examination had not yet been so 
close and detailed as to detect the thin interrupted beds of 
conglomerate at the base, nor the Graptolitic Mudstones, nor 
the Austwick Flags or Grits, as subdivisions which might be 
locally separated and often identified in widely separated areas. 
We have, therefore, to be careful to avoid the confusion that 
might arise from our sometimes quoting the earlier writers 
who used the term Coniston Flags for the whole, and another 
