Vol. 52.] AT BARKY, GLAMORGANSHIRE. 48$ 



Forest Bed. Its recent distribution on the Continent is also very 

 partial, but its seeds have lately been noted in abundance in peaty 

 deposits, perhaps of the same age as those of Barry, in parts of 

 Sweden and Holstcin. 



Mr. Eeid remarks also that there is nothing in the fauna or 

 flora to indicate any change of climate. 



The facts detailed above seem to admit of but one explanation, 

 namely, that the land has subsided at least 55 feet since the forma- 

 tion of peat no. 11. In dealing with such deposits we have to bear 

 in mind that the sea is capable of raising barriers against itself, and 

 that behind such barriers freshwater deposits may be forming, or 

 even a land-surface may exist at a level below that of the highest 

 tides, though never below mean sea-level. As bearing on this 

 question I have noted from the Ordnance-map the levels of some 

 of the marshes now bordering the Bristol Channel : — 



Feet above 

 Ordnance-datum. 

 Sully Moors, the alluvial flat of the Cadoxton River, 



1 mile above Barry 18 



Cardiff (Orange Town), near the Taff River 18 



Cardiff East Moors 20 to 22 



,, „ near the Rhymney River 18 



Cardiff (Cooper's Fields) 25 



Peterstone Wentloog, 1 mile N.W. of 15 



„ „ 1 mile N.E. of, and near a 

 'gout' 13 



In all these cases, except perhaps the Cooper's Fields, the tide 

 would occasionally overflow the land, were it not artificially kept 

 out. Assuming for the sake of argument that a surface 20 feet 

 above Ordnance-datum is the lowest that would now be safe from 

 such periodic incursions of salt water, we have b5 feet as the 

 difference in level between the land-surface, peat no. 11, and the 

 lowest possible at the present day. At Porthkerry, 1| mile west 

 of Barry, a small stream with an alluvial flat about 150 yards broad 

 debouches upon the shore. The sea has blocked the valley by a 

 barrier of shingle, through which the fresh water escapes by perco- 

 lation. The alluvial flat is liable to floods, though not, I believe, 

 through the incursion of salt water, but only by the ponding back 

 of the fresh. The level of this marsh is about 40 feet above 

 Ordnance-datum, or 75 feet above the lowest peat (no. 11) of Barry 

 Dock. 



In none of these alluvial flats, nor elsewhere in the Bristol 

 Channel, do we approach conditions under which the Barry Dock 

 deposits could have been formed. If we assume that the sea had 

 raised against itself an effectual barrier at the mouth of the Cadoxton 

 River, and that it had not yet gained access to the river-valley by 

 the gap on the eastern side of the island, we must then allow the 

 existence of a freshwater lake, for the land-water would accumulate 

 behind the barrier to at least mean sea-level. That is to say, we 

 should have to assume that water stood at a depth of over 36 feet 

 where we find evidence of a land-surface, with forest trees growing 



