496 REPORT — 1893. 



General Eesults of Boring Operations. 



In considering the results obtained by the boring operations we must 

 bear in mind that this method of examination is not so rigidly accurate 

 as excavations from the surface. Even with the most careful manipula- 

 tion of the tubes it is almost impossible to prevent minute organisms 

 such as Foraminifera being carried down to lower levels from overlying 

 deposits. Again, shells might occur in a bed of clay, and yet tbe sample 

 of the material brought up by the boring-tube might not yield any traces 

 of such organisms. A remarkable instance of the latter experience may 

 here be adduced. In the case of bore No. 1, which was put down at the 

 edge of the ' main pit,' upwards of 7 feet of the dark blue clay was 

 pierced, and yet not a single shell fragment was found in the sample of 

 this clay sent to Mr. Robertson nor by members of the Committee on the 

 spot, though from direct observation in the 'main pit' we know that shells 

 are met with in this part of the deposit. 



Important results were obtained from bore No. 1, which was put 

 down within 5 feet of the edge of the 'main pit.' The solid rock, con- 

 sisting of coarse pebbly grit of Old Red Sandstone age, was reached at a 

 depth of 45^ feet. Though crushed by the borer's tools the rock was 

 readily recognised as identical with the coarse grit or fine conglomerate 

 found at the foot of the cliff near Allt Ruadh, about 330 yards north-east 

 of bore No. ] . No less interesting is the result that the rough gravel 

 and sandy clay underlying the shelly clay in the ' main pit ' was 

 found to rest on 21^ feet of ' brown clay and stones.' The only 

 organisms obtained by Mr. Robertson from the sample of this latter 

 deposit are Foraminifera. From the evidence at their disposal the 

 Committee do not feel justified in forming a definite opinion regarding 

 this deposit. 



In bore No. 2, 44 yards south-west of bore No. 1, the blue shelly clay 

 was reached at a depth of 16 feet, or 495i feet above sea-level. The 

 sample yielded fragments of the following shells : Lacuna divaricata and 

 Littorina ohh(sata, with Ostracoda and Foraminifera. 



In bore No, 3, 92 yards south-west of bore No. 1, dark blue sandy clay 

 was pierced at a depth of 2ci^ feet, which was recognised in the field as 

 bearing a close resemblance to the typical blue grey clay of the ' main 

 pit.' Curiously enough, no organic remains seem to have been recorded 

 from the sample examined by Mr. Robertson. 



The blue clay was not found in bore No. 4 at a depth of 25 feet. 

 Had funds permitted the Committee were anxious to try a deeper bore 

 on the cliff further south. 



At a distance of 61 yards, north-east of bore No. 1, a trial bore. 

 No. 5 did not encounter the blue clay. Bore No. 6 was sunk 14 feet 

 further up the face of the cliff, and though again the typical blue clay 

 was not met with, interesting results were obtained. In the hard-bound 

 sand, at a depth of 21 to 24 feet, spines of Echinus and Spatangus were 

 met with, while in the hard brown clay and stones (depth 27 feet) one 

 crustacean was found. 



The final bore, No. 7, was sunk 30 yards north-east of bore No. 1 : it 

 pierced the blue clay at a depth of 11^ feet from the surface, the thickness 

 of the deposit amounting to 2^ feet. It yielded Ostracoda and Foramini- 

 fera, while similar organisms were met with in the overlying ' hard- 

 bound sand ' at a depth of from 8 to 9 feet. 



