Yol.  49.] 
METAMORPHIC  ROCE3  AROUND  THE  SHAP  GRANITE. 
359 
30.  Supplementary  Notes  on  the  Metamorphic  Rocxs  around  the 
Shap  Granite.  By  Alfred  Hareer,  Esq.,  IE. A.,  E.G.S.,  and 
J.  E.  Harr,  Esq.,  M.A.,  E.R.S.,  Sec.  G.S.,  Eeliows  of  St.  John's 
College,  Cambridge.  (Read  April  26th,  1893.) 
[Plate  XVII.] 
Contexts.  Page 
I.  Introduction  . 359 
II.  Metamorphism  of  the  Basic  Rocks  .  360 
III.  The  Silurian  Beds  of  Wasdale  Beck  .  365 
IV.  Conditions  attending  the  Formation  of  Secondary  Felspar-crystals...  366 
V.  The  Metamorphosed  Coniston  Limestone  Beds  of  Wasdale  Head  ...  367 
VI.  Some  Concluding  Considerations .  368 
VII.  List  of  Metamorphic  Minerals  of  the  Shap  District  .  370 
I.  Introduction. 
In  a  paper  presented  to  this  Society  two  years  ago  we  described  at 
some  length  the  phenomena  of  metamorphism  exhibited  by  the 
various  volcanic  and  sedimentary  rocks  around  the  Shap  Granite.1 
Since  that  time  re-examination  of  some  of  the  rocks,  in  the  light  of 
what  we  have  seen  in  other  parts  of  the  Lake  District,  has  enabled 
us  to  make  certain  corrections  and  additions  to  our  work  ;  and  we 
now  offer  these  with  the  intention  of  rendering  the  description  of 
the  metamorphism  in  some  measure  more  complete. 
The  chief  correction  we  have  to  make  relates  to  the  volcanic 
rocks  on  the  northern  side  of  the  granite,  which  we  formerly  classed 
with  the  intermediate  rocks  (andesitic  lavas  and  ashes)  seen  to  the 
west  of  the  granite.  W e  now  find  that  they  constitute  a  distinct  group 
of  more  basic  composition.  To  such  a  conclusion,  indeed,  we  should 
have  been  led  by  the  low  silica-percentages  of  some  metamorphosed 
specimens  from  Low  Eell,2  a  fact  which  we  contented  ourselves  with 
recording  as  inexplicable  on  the  supposition  that  the  rocks  had  been 
originally  similar  to  the  Stockdale  andesites.  W e  have  since  learnt 
that  basic  lavas  are  very  widely  distributed  over  the  Lake  District, 
and  that  the  rocks  on  the  northern  side  of  the  Shap  Granite  must 
be  placed  in  this  division.  They  may  with  propriety  be  named 
basalts,  although,  on  account  of  the  absence  of  oliviue,  somepetro- 
graphers  would  prefer  to  call  them  basic  andesites.  Since  our 
description  of  the  metamorphosed  intermediate  rocks  was  founded  on 
a  traverse  along  a  definite  line  of  strike  through  Sleddale  Pike,  it  is 
not  materially  affected  by  this  correction  of  the  mapping ;  but  two 
or  three  features  which  we  noted  incidentally  as  of  exceptional 
occurrence  in  the  metamorphosed  andesites  were  really  observed  in 
the  rocks  to  the  north.  These  will  be  pointed  out  in  the  brief  de¬ 
scription  which  we  now  proceed  to  give  of  the  metamorphism  of  the 
basic  rocks. 
1  Quart.  Journ.  Geol.  Soc.  yol.  xlyii.  (1891)  p.  266. 
2  Xamely,  50‘75  and  50  90,  ibid.  p.  300. 
