OF THE OUTER HEBRIDES, 



827 



had evidently been ploughed out by other than mere aqueous erosion. 

 The sand and clay together formed low hummocks or hillocks, rising 

 only a few feet over the general surface of the ground. 



Mr. Caunter informs me that the clay has been got as thick as 

 16 feet, and does not show any trace of bedding as a rule. It is 

 generally, he says, very compact and solid, with sometimes a seam 

 or two of sandy clay. No large boulders occur in it, but now and 

 again small stones and a few shells are met with. At one place the 

 clay was overlain by a bed of well-laminated clay, in which sea- 

 weed, " like a mass of the common tangle," was found. " The 

 tangle," Mr. Caunter writes me, " stood erect as high as 6 feet, and 

 extended over a length of 13 feet and a breadth of 7 feet. It ap- 

 peared to have grown on the solid unstratified brick- clay, and to 

 have been subsequently buried in the successive layers of muddy 

 material which now form the overlying stratum of laminated clay." 

 Sometimes the clay rests directly on the Cambrian conglomerate, 

 at other times it is underlain by blue till or boulder-clay, or, as the 

 case may be, by shelly sand, like an old beach-deposit. It is over- 

 lain by a considerable depth of fine sand in some places. 



The clay, Mr. Caunter remarks, has "the appearance of having 

 been ploughed or scored out, and bears evident marks of having been 

 subjected to great pressure and force," red till reclining against and 

 upon it, as exhibited in the annexed illustration (fig. 6), which shows 

 a section exposed at the brickworks during the course of 1876. 



Pig. 6. — Section at Brick-works, Garrabost, Lewis. By Mr. H. 



Caunter. 



a. Bed Till. b. Amorphous brick-clay. 



c. Stratified brick-clay, with sea- weed. 



Brownish sand, with no shells, which is most probably of late 

 glacial age, sometimes overlies all the glacial deposits, and goes up 

 to a height of 200 feet. 



The beds now described occur at a height of 175 feet above the 

 sea, and are in all probability of the same, or approximately the 

 same, age as the similar beds in the north of the island. 



Some twenty years ago Dr. Davy (brother of Sir Humphry Davy) 

 took a collection of shells from the Garrabost clay to the Museum in 

 Jermyn Street for determination ; and Mr. Caunter informs me the 

 fossils were decided at that time to be of glacial age. Unfortunately 

 I have not been able to trace the whereabouts of this collection; for 

 there is no record of the shells in the books at Jermyn Street, and, 

 as Mr. Etheridge tells me, not a single specimen from any glacial 

 deposit north of the Kyles of Bute occurs in the Museum. Mr. 



