68 DR T. J. JEHU ON 
Rattway Curttrine (between Tregroes moor and Manor-owen)— 
Pectunculus glycimeris, L. 
Cardium islandicum% Chem. 
Vulsella modiola? L. 
Astarte sulcata, Da Costa. 
Astarte (Nicania) compressa, Mont. 
Venus (Ventricola) casina, L. 
Cyprina islandica, L. 
Some of the boulder-clay from the boring near Treeroes was washed and examined 
under the microscope. A good deal of very fine sandy material—mostly quartz—was 
observed, and a few foraminifera could be seen. 
2. The Sands and G'ravels,—Above the Lower Boulder-Clay comes a series of aqueous 
deposits, consisting of sands and gravels, which are sometimes stratified and sometimes 
show hardly any traces of stratification. These deposits vary very much in thickness, 
and are apt to die out suddenly when traced laterally. They usually occupy a higher 
level than that attained by the Lower Boulder-Clay, and are often seen banked on the 
lower slopes of the hills. In places where sections are seen passing through the 
different deposits, no gradual passage can be traced from the lower stiff blue clay to 
the sands and gravels above—and this suggests that the sands and gravels lie upon an 
eroded surface of the clay. The sands are as a rule yellowish and yellowish-brown in 
colour, and have all the appearance of being marine: they are very variable in texture, 
and show all gradations from very fine sand to coarse gritty sand and gravel. And 
the gravels are often coarse and pebbly, resembling the shingle collected on beaches. 
At some places the sands are charged with worn and broken fragments of marine 
shells: these usually occur more abundantly in the fine gravel or coarse gritty sand 
than in the fine sand, although minute flakes can often be detected in the latter. They 
seem to be collected together in the stratified beds at certain spots, and to be absent 
in somewhat similar beds exposed only a short distance away. For instance, shells are 
plentiful in the Manor-owen sand-pit, whilst not a trace of shells can be seen in the 
Cnuce sandy pit, which hes only about a quarter of a mile further south: and 50 yards 
or so beyond the Cnue sandy pit shell-fragments are again found in sand exposed in 
the railway cutting. In the pits where shell-fragments are found it may often be 
noticed that small pieces are cemented to the surface of a rounded stone. This is 
doubtless due to a deposit of carbonate of lime derived from the decay of some of the 
shells. 
Like the Lower Boulder-Clay, the deposits of sand and gravel become better 
developed when traced from west to east, and the best sections and pits can be seen in 
that part of the district lying to the east of Strumble Head. Though the St David’s 
promontory is largely covered by a loamy sand, no sections were seen showing deposits 
of the well-marked marine-like sands and gravels found further east. At Ty-llwyd 
there are small pits reaching a depth of 5 to 6 feet, where the loamy sand is well 
