567 



of felspar somewhat sparingly developed, and the presence 01 

 limonite, partly filling some of the cavities in the stone, may 

 point to these spaces having been originally filled with iron 

 pyrites. The dyke, which does not follow the direction of 

 the main limestone or associated beds, is about 200 yards in 

 length and ends abruptly at the crest of the higher ridge, 

 where it is cut off by slates. There is a certain similarity 

 between this dyke and the porphyritic development in No. If, 

 but the intrusion now under description has, apparently, 

 undergone greater alteration. 



Group fcj IN CREEK NEXT ABOVE CATHEDRAL-ROCK CREEK. 



No. 12. — This exposure occurs a little to the westward 

 of the last described (No. 11) and about 200 yards to the 

 south-east of the dyke (No. 6) at the old mine. The ridge 

 on which most of the igneous dykes so far described occur 

 forms the watershed between the Cathedral-rock Creek and 

 another creek next above it. The present outcrop is situated 

 a little over the ridge on its southern side. It appears to be 

 approximately circular in outline, and is indicated by a large 

 number of broken rocks on the surface. It extends for about 

 one-third of the distance down the slope towards- the creek 

 next above the Cathedral-rock Creek. There appears to be 

 a small dyke on the western side of the one just referred to, 

 as a number of dyke stones were noticed in the line of a small 

 depression on the slope of the hill, but they were mixed with 

 other rock fragments and their source could not be definitely 

 located. 



No. 13. — There is a small exposure of a basic dyke at 

 the mouth of the last-named creek where it unites with the 

 main stream a little above the spot where the main limestone 

 crosses the Mount Creek. The dyke occupies the left bank 

 of the stream and runs parallel with the same for a short 

 distance, but does not appear to be very thick. 



No. lJf— -About 100 yards up the same creek a strong 

 exposure of an igneous dyke is seen on both sides of the creek. 

 It has a strike S. 20° W., is about 40 yards wide, and can 

 be traced along the line of outcrop for about 80 yards. 



No. 15. — A little higher up the creek than the last- 

 named another dyke makes a prominent feature on the right 

 bank of the stream. It forms a circular knoll that imme- 

 diately attracts attention. The texture of the rock varies 

 from medium-grain to coarsely-crystalline. 



No. 16. — On the right bank of the same creek, near its 

 confluence with the Mount Creek, surface stones indicate the 

 outcrop of another basic dyke. It is situated at the back of 



