THE GLACIAL DEPOSITS OF WESTERN CARNARVONSHIRE. 43 



The marshy land below, known as Cors Geirch, is underlaid by Boulder Clay. This 

 Cors probably marks the site of a former lake. 



At Nanhoron there is an old sand pit in the field in front of the house. It is now 

 partly filled up, but formerly it was open to a depth of over 10 feet. Fine marine-like 

 sands, well-bedded, are still exposed, with gritty layers here and there. These sands are 

 of considerable thickness, for on digging to a depth of over 1 feet their base was not 

 reached. The entire hill on which the house stands is rounded over by these sands. 

 But to the south, where the Afon Horon runs at a lower level, the stream has exposed 

 the lower stiff bluish-grey Boulder Clay which here, as in the coast sections, underlies 

 the Sands and Gravels. The stream has here not cut through the Boulder Clay. 



Passing north to the neighbourhood of Madryn we still find similar features. In a 

 field on rising ground some 200 yards south of the Hall, and 60 feet above it, sand and 

 fine gravel are seen just below the surface. The sand is of the same character as that 

 met with at Nanhoron. Again, in the park to the north of the Hall, fine yellow sand is 

 exposed in many places and is often seen brought up from rabbit burrows. A large 

 area is here covered by this sandy deposit. 



At Meillionen. near Ceidio, coarse gravelly sand is exposed at the surface and to 

 a depth of 4 to 5 feet. In the lower ground adjoining, the stiff Boulder Clay is 

 met with. 



At Cefn-leisog, in a field just south of the farmhouse, lies a disused sand pit. Here 

 the sand is covered by 4 to 5 feet of yellowish weathered clay full of boulders. 



Passing to Brynodol we find that much of the land north of the house is sandy, as 

 seen in several poor exposures and in newly dug ditches. 



At Ty-Issa, Tydweiliog, a boring was recently made for water. The deposits 

 traversed were as follows : — 



3. Sand — 6 feet. 



2. Stiff bluish-grey Boulder Clay— 27 feet. 



1. Coarse sand — 3 feet. (The bottom of this sand was not reached.) 



A little higher up, at the County School, Tydweiliog, a boring was also made, and 

 this passed through : — 



2. Sandy Clay— 16 feet. 



1. Pure Sand — 2 feet, the bottom of which was not reached. 

 A little further down the slope of the same hill another boring was made which 

 passed through nothing but marine-like sand to a depth of 10 feet. So we may gather 

 from these various borings at Tydweiliog that the Drift covering the land in this 

 neighbourhood consists of: — 



3. Sandy Clay. 

 2. Sands. 



1. Stiff bluish-grey Boulder Clay, which at one place at any rate is underlaid by or 

 includes Sands. 



