438 
TlDDEMAN : LIMESTONE CONGLOMERATES. 
Evidence pointed to their having grown up as reefs on a slowly sinking 
bottom by the growth and death of the animals of whose remains 
they are formed. It was shown that they were formed in shallow 
seas, and that the tops of them were often awash in the turmoil of 
the waves. In short they formed islands or reefs. One of the points 
of evidence was the frequent occurrence on their sides or on the sea- 
bottoms surrounding them of angular fragments of the limestone, 
which had evidently been broken off from them in the surge of the 
sea, and had either accumulated on their sides at an angle of rest or 
had been consigned to the deeper water below, and subsequently 
covered up by the shale and mud of a later stage. These so-called 
breccias were generally made of angular fragments, but occasionally 
the pieces were well rolled into pebbles, and the deposit might be 
called a conglomerate. 
In summing up the bearing of these and kindred facts on the 
geography of these Carboniferous Seas I wrote as follows : — " If we 
ascend to the top of the crags above Malham Cove we soon find our- 
selves upon the great plateau of the Mountain Limestone proper. 
This, though broken at the foot of Malham Tarn by the North 
Craven Fault which throws up the base and shows us how thin it is, 
and crossed by many minor faults, is one and the same as the great 
spread of Mountain Limestone which lies beneath all the Yorkshire 
Dales, and extends north beyond the Tyne Valley. We have crossed 
the Fault and in so doing have exchanged the Clitheroe or Bolland 
series for the Yoredale type, and if we could realize the state of 
affairs when these rocks were forming we should probably say that 
we had left a deep sea dotted with islands and come on to a wide 
and long and shallow reef." The sea with the islands was a genera- 
lization, the result of a very fair amount of evidence. The long reef 
was hardly more than a conviction based on probabilities. Some 
evidence I had seen, but hardly enough to form a satisfactory 
demonstration, and at first sight it seemed unlikely that any remains 
of the beach of that supposed reef, ranging along the flanks of the 
high hills which border on the Craven Faults, would be present, if it 
had ever existed. 
It was, therefore, a pleasant surprise when I was working in the 
