ON THE SHELL-BEARING DEPOSITS AT CLAVA, AND OTHER PLACES. 489 



At this latter locality (233 yards S.W. of the ' main pit ') a mass of 

 fine bard brown clay is exposed at the foot of the cliff, rising to a height 

 of 8 or 9 feet above the stream, and 523^ feet above sea-level. For a depth 

 of 6 or 7 feet it is entirely free from stones, but at the level of the burn a 

 few occur, though very small. Though no organic remains have been 

 found in this deposit, and though it diSers in colour from the typical 

 shelly clay of the ' main pit,' some of the Committee are inclined to regard 

 it as belonging to the same formation. The chemical analysis of the 

 material is interesting. It was found by Mr. W. Ivison Macadam, Edin- 

 burgh, to contain 31 per cent, of ferric oxide, and slightly over 1 per 

 cent, of aluminic oxide. ' It is not a clay, strictly speaking, but a sand 

 bound together by iron.' ' 



Clava Shell-heel. — Percentages of stones from tie loivest 6 ft. of shelly clay, 

 and from the highest 9 ft. of gravel helow the shelly clay, and also from 

 boulder clay above shelly clay, from lists written to Mr. Home's dictation 

 on the ground. 



C. — Boring Operations. 



On reaching the depth of 10 feet below the shelly clay in the 

 ■•main pit,' the Committee found that they could not carry the exca- 

 vation further down without timbering the trench ; and this could not 

 be safely done so close to the cliff. Being desirous of reaching the 

 «olid rock near the site of the main section, and also of proving the 

 horizontal extension of the shelly clay, they resolved to make a series of 

 bores. For this purpose they employed Mr. Pollock, an experienced 

 mineral borer from Airdrie. 



The accompanying ground plan on the scale of 325 feet to the inch 

 shows the relative positions of the various bores. In fixing the sites the 

 object of the Committee was to prove the extension of the shelly clay 

 along the south bank of the Cassie Burn. Two boi-es were put down 



' Trans. Geol. Soc. JSdin., vol. iv. Part ii. 



