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separates the small island of Holyhead. The hay at the 
widest part is five miles wide, from the small islet of 
Meihion, south, to the Rhoscolyn beacon islet, north. The 
head of the bay is an immense sand, over which a small 
stream finds its way to the sea. The north and south 
shores are rocky crags, and long islets of jagged and rough 
rocks occur at intervals in the bay, making it a source of 
danger to any vessels that drift from the channel, or in a 
fog lose their course and sail with the strong western winds 
right into the bay. 
In places where the high cliffs have been worn away the 
shore is shallow and has miles of firm sand, whilst these 
sands are fringed with sand dunes, which inland stretch 
away in barren and wild commons with small bosses of 
rocks. The district is rarely visited by strangers, and alto- 
gether is a wild, stormy, and mainly uncultivated district. 
The rocks are grand for geological study ; they are black 
slates, shales, serpentines, quartzites, granites, and conglo- 
merates of Cambrian age. The last rocks are mines of the 
most valuable knowledge for the study of primitive rocks of 
pre-Cambrian age. 
The sandy shores are extensive at the head of the bay ; 
with continuous winds from the west and south the breakers 
are fearfully heavy, and the sea so rough that no boat from 
the shore can be launched by the fishermen for many weeks 
together; calms are rare and uncertain, so that fishing is 
precarious ; at low tides a fine expanse of shore is exposed, 
as dry and as level as a bowling green, with the bosses of 
black and bright green rocks striking out of the level. 
The conchologist would be greatly disappointed if he paid 
but a brief visit to the shores. He might walk all day and 
conclude that the sand was extensive but as barren of shells 
as a snowdrift. But with leisure and perseverance parts of 
the shore are found to be teeming with some species, and in 
the rocky pools and quiet caverns and corners many rare 
