ON MICA-TRAPS FROM KENDAL AND SEDBERGH. 165 
12. On some Mica-trRaes from the Kunpat and Sepseren Disreicrs. 
By Rev. T. G. Bonnny, M.A., F.R.S., Sec.G.S., Professor of 
Geology at University College, London, and Fellow of St. John’s 
College, Cambridge, and F.T. 8. Hoveuron, Esq., B.A., Scholar 
.of St. John’s College, Cambridge. (Read December 4, 1878.) 
Unper the convenient generic term mica-trap the Geological Survey 
of England has included a group of rocks which are generally rich 
in that mineral, and occur among the older Paleozoic strata of the 
north-west of England. ‘These rocks are found in dykes usually of 
no great thickness, and often very imperfectly exposed; and they 
have been mapped on quarter-sheet 98 N.E., and in the adjacent 
corners of the yet unpublished 98 S8.E. and 97 S.W. A brief 
notice of the dykes is also given in the accompanying memoirs, 
‘Kirkby Lonsdale,’ p. 42, and ‘ Kendal and Sedbergh,’ p. 16. With- 
out microscopic examination and chemical analysis, it was not pos- 
sible, as a rule, to attempt a more exact nomenclature, so that, in 
our opinion, the use of the term mica-trap, like felstone, greenstone, 
&c., is not only convenient, but justifiable, where for any reason a 
more exact investigation is not practicable at the time. The present 
paper, although very far from being a complete history of all the 
mica-traps of North-western England, may form, it is hoped, a first 
chapter in it, and be the means of evoking further contributions to 
the lithology of this interesting and not very common group of 
rocks*, 
Mica-traps, so far as we are aware, are either very rare or wholly 
absent in Britain to the south of the Cumbrian district, and in that 
they are rarely found in the vicinity of the principal lakes, but are 
almost confined to the eastern part of Westmoreland and the north- 
western of Yorkshire, always occurring in Silurian rocks. They 
are also met with among the Lower Silurian strata of the southern 
uplands of Scotland, and in several localities in Ireland, where also 
they are intrusive in the older Paleozoic rockst. Mica-traps also 
occur in the Channel Islands, Saxony, the Vosges Mountains, Baden, 
and North-western France, also in the Pyrenees and West-central 
France. Specimens from some of these districts have been used for 
comparison§. 
* For the lithological work herein Prof. Bonney is responsible, for the che- 
mical analyses Mr. Houghton. A few of the dykes have been examined in the 
field by the former, under the guidance of Professor Hughes, without whose 
minute local knowledge it would have been hardly possible to find one or two 
exposures. For most of the other specimens, and for notes on their relations 
to the stratified rocks, the authors are indebted to the kindness of their friend 
J. H. Marr, Hsq., B.A., F.G.8., Scholar of St. John’s College, to whom they 
tender their best thanks. 
t Messrs. Gunn and Clough, Quart. Journ. Geol. Soc. vol. xxxiy. p. 30, ex- 
pressly state that they never occur in the Carboniferous strata. 
i Hull, ‘On Building-stones,’ &e. p. 84, cf. p. 9. 
5 So far as we can judge from the figure, the rock described by Mr. J. H. 
