(Jr. W. Robinson 375 



No calcium carbonate has been found in any of the estuarine or 

 fluviatile alluvia. 



Peat Soils. 



The North Wales peats fall into two main classes namely shallow 

 peats and deep peats. 



I. Shallow peats occur over a large part of the uplands of Denbigh- 

 shire and in western Carnarvonshire. They consist of a thin layer of 

 peat (up to 12 inches) lying on gravelly loam or clay subsoils. A pro- 

 visional subdivision may be made into (a) the Denbighshire type, 

 occurring from 600 feet to 1200 feet lying over Silurian and Ordovician 

 shale subsoils, and (h) the Carnarvonshire type occurring from 100 feet 

 to 800 feet and lying over glacial drift subsoils. Both sub-types are 

 little cultivated but in certain favoured spots successful reclamation 

 has been carried out. As might be expected, cultivation leads to a 

 diminution in the content of organic matter. This is well shown by 

 the comparison of two soils from Llanllyfni. C15 was taken from a 

 root field in a small holding, while C 16 was taken from the unenclosed 

 waste on the other side of the boundary wall. 



The average composition of five peats of this class is shown in the 

 general table. It will be seen that the figures for organic matter fall 

 within fairly close limits. The organic matter in the subsoils, as may 

 be expected in shallow peats, is much less than that in the soils. 



Calcium carbonate is invariably absent. 



II. Deep peats. The continental workers on peat distinguish three 

 stages in the building of deep peat. They are, in vertical succession, 

 (a) Fen, Flachmoor, or " Niedermoor," (6) a transition type known as 

 Ubergangsmoor, and (c) Hochmoor. All three types can be observed 

 in North Wales. A thorough investigation of the deep peats will more 

 appropriately form the subject of another paper and, for the present, 

 outlines only can be given. 



(a) Fen. Only one true fen peat has been examined in the labora- 

 tory. It was of the typical "Niedermoor" structure and composition, 



25—2 



