S30 GEOLOGICAL APPEARANCES 



nate of lime or magnesia, and another composed of red felspar, 

 hornblende, and carbonate of lime. The latter is very similar 

 to the red sienite ; but the substances are not so highly crystal- 

 lised, as is commonly the case in the sienite. Within twenty 

 yards, these are succeeded (at 3) by a compound of brown fel- 

 spar, quartz, and a small proportion of compact dolomite. 

 The decomposed state of these rocks, and their complex cha- 

 racters, make it difficult to ascertain their ingredients with 

 much precision. The rock last described bears some slight 

 marks of stratification, but the stretch indicated by them is in 

 a direction nearly at right angles to that of the strata on the 

 opposite side of the river, for it is nearly at right angles to the 

 course of the channel : it must be observed, however, that the 

 planes of these strata, if such they are, are much bent. Far- 

 ther up, on the southern bank, (at 3 in the plan) and in the di- 

 rection of between 43° and 53" E. of N. from this point, there 

 are rocks of substances similar in character to some of those 

 hereabouts ; and these are in distinct strata, dipping south-east, 

 conformably with the neighbouring strata of limestone. 



73. About the place where these strata appear on the north- 

 ern bank, the line of the bank turns to the northward ; and 

 from hence to the bridge, a distance of near a hundred yards, 

 there is a straight reach of the river. On both sides of it, the 

 banks are high and steep, and the margin of the water is 

 indented by many projections of the rock. 



74. In proceeding towards the bridge about twenty yards 

 alonof the foot of the northern bank, the rock is found to va- 

 ry considerably. It is often a mixture of compact felspar and 

 quartz, and sometimes a pure granular quartz, but the fel- 

 spar is generally the predominant substance ; sometimes also 

 it approaches to a gneiss. Specks of pyrites occur among 

 these substances. Their structure is not stratified, and, if they 



are 



