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542

 MAJOK-GENERAL 
 C. 
 A. 
 M'MAHON 
 ON 
 THE 
 HOBXBLENDE-SCHISTS 
 

The

 facts 
 seem 
 to 
 lead 
 naturally 
 to 
 this 
 conclusion, 
 and 
 I 
 do 
 not 
 

see

 how 
 it 
 can 
 be 
 avoided. 
 

This

 being 
 so, 
 the 
 further 
 inferences 
 seem 
 natural 
 that 
 the 
 eruptions 
 

of

 diorite 
 and 
 granite 
 in 
 the 
 cliff 
 at 
 Kennack 
 Cove 
 belong 
 to 
 the 
 

same

 period 
 as 
 the 
 intrusions 
 of 
 diorite 
 and 
 granite 
 into 
 the 
 rocks 
 

on

 the 
 Kennack 
 foreshore, 
 and 
 that 
 the 
 injection 
 of 
 the 
 dioritic 
 rocks 
 

at

 Kennack 
 Cove, 
 in 
 the 
 form 
 of 
 quasi- 
 banding, 
 took 
 place 
 during 
 

the

 same 
 period. 
 

If

 the 
 rocks 
 of 
 the 
 "granulitic" 
 group 
 at 
 Kennack 
 Cove 
 and 
 Cavouga 
 

were

 injected 
 with 
 granite 
 subsequent 
 to 
 the 
 intrusion 
 of 
 the 
 por- 
 

phyritic

 diorite, 
 the 
 same 
 conclusion 
 holds 
 good 
 for 
 those 
 on 
 the 
 

sea-shore

 at 
 Holestrow, 
 Pentreath, 
 and 
 under 
 Yellow 
 Cam: 
 but 
 

the

 question 
 remains 
 whether 
 the 
 bedded 
 " 
 granulite 
 " 
 at 
 Pen 
 

Yoose

 and 
 in 
 that 
 neighbourhood 
 ought 
 not 
 to 
 be 
 separated 
 from 
 

them,

 and 
 whether 
 both 
 series, 
 viz. 
 the 
 Pen-Yoose 
 " 
 granulites 
 " 
 

and

 the 
 Kennack 
 and 
 Holestrow 
 rocks 
 of 
 " 
 granulitic 
 " 
 aspect, 
 were 
 

injected

 with 
 granite 
 during 
 the 
 same 
 or 
 at 
 different 
 periods. 
 On 
 

these

 points 
 I 
 think 
 it 
 prudent 
 to 
 suspend 
 judgment 
 for 
 the 
 present. 
 

There

 are 
 several 
 matters 
 connected 
 with 
 these 
 questions 
 that 
 require 
 

elucidation.

 Faults 
 are 
 so 
 abundant 
 along 
 the 
 coast 
 of 
 the 
 Lizard 
 

that

 the 
 apparent 
 relation 
 of 
 the 
 " 
 granulitic 
 " 
 rocks 
 to 
 the 
 horn- 
 

blende-schists

 differs 
 materially 
 in 
 different 
 places. 
 

One

 more 
 exposure 
 requires 
 to 
 be 
 briefly 
 noted. 
 At 
 the 
 north 
 

end

 of 
 Kildown 
 Cove 
 three 
 strips 
 of 
 the 
 "granulitic" 
 group 
 are 
 to 
 

be

 seen 
 in 
 serpentine 
 cutting 
 across 
 the 
 root 
 of 
 the 
 Eny's 
 Head 
 

under

 circumstances 
 that 
 give 
 colour 
 to 
 Air. 
 SomervaiFs 
 theory 
 that 
 

the

 "granulitic" 
 rocks 
 have 
 intruded 
 into 
 the 
 serpentine. 
 Prof. 
 

Bonney's

 explanation 
 of 
 this 
 section 
 is 
 that 
 the 
 serpentine 
 is 
 intrusive 
 

in

 the 
 " 
 granulitic 
 " 
 group. 
 My 
 own 
 view 
 is 
 that 
 the 
 position 
 of 
 

the

 " 
 granulitic" 
 rocks 
 here 
 is 
 due 
 to 
 faulting. 
 The 
 more 
 westerly 
 

of

 the 
 three 
 strips 
 has 
 the 
 appearance 
 of 
 being 
 faulted 
 against 
 the 
 

serpentine

 ; 
 for 
 a 
 broad 
 dyke 
 of 
 gabbro 
 that 
 strikes 
 at 
 the 
 "granulite 
 " 
 

at

 a 
 high 
 angle 
 ends 
 sharply 
 at 
 the 
 " 
 granulite 
 " 
 and 
 does 
 not 
 reappear 
 

in

 the 
 serpentine 
 on 
 the 
 other 
 side, 
 which 
 it 
 would 
 surely 
 do 
 if 
 

the

 " 
 granulite 
 " 
 had 
 been 
 erupted 
 through 
 the 
 serpentine 
 and 
 its 
 

contained

 gabbro. 
 The 
 natural 
 inference 
 is 
 that 
 the 
 gabbro 
 is 
 cut 
 

off

 by 
 a 
 fault. 
 

Discussion.

The

 President 
 noticed 
 the 
 revival 
 of 
 Bischofs 
 views. 
 The 
 

supposed

 ash-beds 
 the 
 late 
 David 
 Forbes 
 was 
 perhaps 
 right 
 in 
 

considering

 had 
 been 
 produced 
 by 
 lava 
 issuing 
 into 
 water. 
 

Dr.

 G-eikie 
 would 
 be 
 reluctant 
 to 
 accept 
 the 
 Author's 
 conclusions. 
 

Though

 he 
 had 
 not 
 examined 
 the 
 ground, 
 he 
 could 
 not 
 believe 
 that 
 

the

 rocks 
 there 
 had 
 escaped 
 from 
 the 
 deformation 
 which 
 was 
 so 
 

manifest

 throughout 
 Cornwall. 
 

Mr.

 Teall 
 commented 
 on 
 the 
 complexity 
 of 
 the 
 subject. 
 The 
 

district

 had 
 been 
 examined 
 by 
 Dr. 
 Bonney, 
 and 
 subsequently 
 by 
 

himself,

 and 
 although 
 on 
 some 
 points 
 the 
 Author 
 reconciled