1. Lake District Mapping Vol. II Leo M L Ritchie

2. Strategic ~10 2 km area covered Access –Youth Hostel at one end of my area Topography –80m to 650m elevation –Poor sediment outcrops Weather –Mentally unprepared for sun in UK

3. Where I mapped? In the Lake District NW of Coniston

4. Geology of wider area Mapping Area

5. Andesitic Welded Tuff (dwt) Rhyolitic Welded Tuff (mwt) Porphyritic Intrusion (pi) More vs Interbedded Siltstone and Tuff (ist) More vs Lapilli Tuff (lt) Volcaniclastic siltstone and sandstone (vs) Lithic-rich Tuff (lrt) Limestone & calcareous siltstone (lcs) Pale Siltstone (ps) Dark Siltstone (ds) Map & stratigraphic column N Lever’s Water Coniston

6. Succession 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

7. Rhyolitic Welded Tuff (mwt) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

8. Volcanic Rhyolitic Welded Tuff (mwt) Oldest unit Quartz rich homogeneous >200m Caradoc (Ordovician)* *Millward D. et al Geology of the Ambleside district. Memoir for 1:50 000 Geological Sheet 38 (England & Wales) British Geological Survey H.M.S.O. 2000 2nd Session Sheet 38

9. Volcaniclastic sandstone and siltstone (vs) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

10. Volcanic Volcaniclastic sandstone and siltstone (vs) ~1km thickness in three separate units Siltstone – conglomerate

11. Interbedded siltstone and tuff (ist) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

12. Volcanic Interbedded siltstone and tuff (ist) ~200m thickness Dacitic welded lapilli tuffs And volcaniclastic siltstones

13. Lapilli Tuff (lt) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

14. Volcanic Lapilli Tuff (lt) ~50m thickness Only un-welded tuff in the succession dacitic

15. Lithic-rich tuff (lrt) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

16. Volcanic Lithic-rich tuff (lrt) ~400m thickness Dacitic welded tuff Larger lithics were rhyolitic Columnar jointing

17. Unconformity between vs-lrt

18. U/C lrt vs

19. Limestone & calcareous siltstone (lcs) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

20. Sediment Limestone & calcareous siltstone (lcs) ~150m thickness Ashgill (Ordovician)* Fossiliferous…

25. Pale siltstone (ps) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

26. Sediment Pale siltstone (ps) ~30m thickness Llandovery (Silurian)* Bioturbated…

28. Dark siltstone (ds) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

29. Sediment Dark siltstone (ds) >500m unfossiliferous

30. Porphyritic Intrusion (pi) 200 300 400 100 500 600 700 ds pslcs lrt vs pi ist mwt lt

31. Intrusive Igneous Porphyritic Intrusion (pi) ~250m Plagioclase phyric Interesting jointing patterns…

33. And finally… Volcanic Andesitic welded tuff (dwt) >200m thickness Pyroxene and amphibole rich N Lever’s Water

34. Structure Predominant cleavage throughout units Faulting (big & small)

35. Structure - cleavage A predominant cleavage was apparent in most of my units

36. Structure – faulting (big) Normal faulting in lithic rich tuff (lrt)

37. N Lever’s Water

38. N

39. N

40. N 72/ 108

41. Structure – faulting (small) Small scale faulting in volcaniclastic sand/siltstone (vs)

42. Structure – faulting (small) Small scale faulting in volcaniclastic sand/siltstone (vs) Fine grained laminations displaced on cm- scale

43. Structure – faulting (small) Small scale faulting in volcaniclastic sand/siltstone (vs) Fine grained laminations displaced on cm- scale 67/ 328

44. Structure - faulting (strike-slip?) In Eastern corner of my area N Lever’s Water

45. N x

46. ds ps lcs lrt dwt

47. Interpretation 1.Eruption of tuffs and deposition of volcaniclastic sediments 2.Deposition of shallow then deeper marine sediments 3.Strike slip faulting – bringing andesitic welded tuff southward 4.Compression causes cleavage

48. Problems Does compression or strike-slip faulting take place first? Why does pi intrudes within rock types? And when did it intrude.

49. Plans Find out more about tuffs and intrusions from thin sections Provinence study of two vs units Investigate fossils more closely to refine ideas about age

50. Any Questions?