Field project tutorials 2002 - Day 1

Day 1: Notebook entries

Date

 

Location

 

Weather

Raining, occasionally heavy; windy (from west); temperature above freezing at sea level, but could be snowing in the hills; cloud base 500-1000m.

Hazards

New area: mainly open moor land from sea level to over 600m; steep grassy slopes (slippery in wet) and precipitous cliffs; several stream/river sections with fast-flowing water and waterfalls/rapids; restricted coastal section with steep shoreline/cliffs & tidal river estuary (large waves in rough weather).

Need to become familiar with area (e.g. access & excess routes)

Cold & wet (wind chill) - snow above 300m? ; intermittent low cloud.

First-aid

Dr. Geoff Lloyd

Mood

Fantastic: excited to be in the field again & raring to go !

Aims

Obtain basic map details: lithological outcrop pattern and main structural features (i.e. 'boundary tracing'); to construct the basic geological background on which to build the structural and strain analysis framework.

  1. Walk from the field camp (grid reference 003 072) up the main river valley. At 023 049, a large fault is observed, trending approximately N-S, which juxtaposes shattered quartzite against shattered quartzite. Orientation of fault plane: 006/80W. Slickensides on fault plane surface plunge vertically.

Decided to trace out the outcrop of this fault by walking north and then south along its strike.

  1. A large fault outcrops at 028 084 and places shattered quartzite to E against disrupted shales to W; fault plane orientation: 005/79W. Slickensides plunge vertically.
  2. A large fault outcrops at 031 093 and places shattered quartzite to E against disrupted inter-bedded limestones & shales to W; fault plane orientation: 004/81W. Slickensides on fault plane pitch 90° from N.
  3. A large fault outcrops at 033 010 and places the boundary between shattered quartzite and disrupted shales to E against disrupted shales to W; fault plane orientation: 006/80W.
  4. A large fault outcrops at 023 040 and places shattered quartzite to E against disrupted shales to W; fault plane orientation: 004/79W. Slickensides on fault plane pitch 90° S.
  5. A large fault outcrops at 020 005 and places shattered quartzite to E against disrupted inter-bedded limestones & shales to W; fault plane orientation: 007/81W.

Decided to establish the stratigraphy & structure in the relatively small area to the W, between the fault & the coastline.

  1. Walking from 020 005 W towards the sea, the only outcrop found is at 008 010, where a horizontal boundary is observed (Fig. 1a). The quartzite below is horizontally bedded, medium grained, well cemented & contains various sedimentary features (Fig. 1b); it also contains the fossils (Fig. 2). The massive shales above are also horizontally bedded, apparently calcareous, and contain fossils too (Fig. 3).
  2. On the coast at 001 010 (Fig. 5), horizontally bedded quartzite with similar sedimentary structures as Fig. 1b contain fossils (Fig. 4).
  3. At 010 055, a similar outcrop to that at 008 010 is observed.
  4. At 020 072 (Fig. 6), a horizontal boundary between shales (below) and inter-bedded thin limestone-shales (above) is observed. The former are horizontal and contain fossils (Fig. 3); the latter are also horizontal and contain fossils (Fig. 3b and 7).
  5. At 014 090, a similar outcrop to the previous one is observed.
  6. At 027 100 (Fig. 8), a horizontal boundary between inter-bedded thin limestones and shales (below) and massive shales (above) is observed. The former are horizontal and contain fossils (Fig. 3b and 7); the latter are also horizontal and contain fossils (Fig. 3b and 9).
  7. Return to 023 049 and continue walking up river through progressively less shattered quartzite until at 028 050 (Fig. 10) all evidence of fracturing has disappeared and only see a bedded quartzite (167/35E) containing a fossil (Fig. 4). Similar outcrops to this one are seen at:
  8. 037 094
  9. 034 086
  10. 033 077
  11. 028 029
  12. 027 010
  13. Continue walking up river until 058 063 (Fig. 11), where a junction between bedded quartzite and massive shales is observed. Former contain a fossil (Fig. 2); latter contain fossils (Fig. 3). Bedding in both rocks is parallel to the boundary: 169/32E. The shales have a strong cleavage, which is only weakly developed in the quartzite: 020/55E. Similar out crops occur at:
  14. 053 087; and 20. 044 096.
  15. At 060 018, a similar outcrop to that seen at 058 063 occurs, but now the cleavage in the quartzite is also very strong.
  16. 047 007, similar to 060 018.
  17. At 040 001 (Fig. 12) a large fold closure is observed in cleaved quartzite.
  18. Continuing up the river, a junction between shales and inter-bedded limestones/shales is observed at 061 049 (Fig. 13). The former contain fossils (Fig. 3); the latter contain fossils (Figs. 3b and 7). Both rock types are cleaved. Similar outcrops occur at:
  19. 059 091;
  20. 059 093;
  21. 043 100.
  22. Continuing up the river to 069 052, where a junction between inter-bedded limestone/shales and massive shales is observed (Fig. 14). Both rocks are heavily cleaved, but the former has yielded fossils (Figs. 3b and 7); whilst other fossils (Figs. 3b and 9) have been found in the latter. Similar outcrops occur at:
  23. 067 091
  24. 066 097
  25. 057 013.
  26. Further up river at 074 051 (Fig. 15), inter-bedded limestone-shales overlie massive shales. Both rocks are heavily cleaved and extensively sheared and thinned, which has obliterated any fossil evidence for age relationships, although bedding can still be seen in the limestones and is parallel to the boundary. Similar outcrops occur at:
  27. 075 064
  28. 088 093
  29. 092 102
  30. Just above the river at 076 053 (Fig. 16), massive shales overlie inter-bedded limestone-shales. Both rocks are heavily cleaved and extensively sheared and thinned, which has obliterated any fossil evidence for age relationships, although bedding can still be seen in the limestones and is parallel to the boundary. However, the shearing has started to transpose the bedding and cleavage in to a new foliation: bedding: 023/65E; cleavage: 020/55E; foliation: 014/64E

Similar outcrops occur at:

  1. 26a. 089 091
  2. 073 048
  3. 070 042
  4. 069 014
  5. Further up the river, within a prominent gorge, at 078 054 (Fig. 17) , highly cleaved and sheared but still recognisably bedded quartzite overlies highly cleaved and sheared shales: bedding: 023/65E; cleavage: 020/55E; shearing: 014/64E. Similar outcrops occur at:
  6. 077 058
  7. 079 070
  8. 076 049
  9. 071 039
  10. 072 014
  11. 055 008
  12. A little further up the gorge at 082 050 (Fig. 18), cleaved and sheared bedded quartzite is overlain by sheared foliated and rodded 'massive' quartzite containing biotite, with a foliation parallel to the contact. Similar outcrops occur at:
  13. 082 053
  14. 080 055
  15. 079 059
  16. 086 086
  17. 093 097
  18. 094 100
  19. 073 030
  20. 073 019
  21. 070 011
  22. 064 006
  23. Approximately 300m further up the gorge at 109 055 (Fig. 19), a schistose rock overlies massive, weakly foliated (014/64E) quartzite. The former is banded on the mm-cm scale and contains quartz, feldspar, mica, amphibole and garnet. The latter contains biotite. The schist is sheared parallel to the contact (173/27E). Similar outcrops occur at:
  24. 109 055
  25. 099 056
  26. 104 092
  27. 114 013
  28. 114 006

Daily Summary

(remember to summarise your observations & to begin to evolve ideas about this region).

 

 

 

 

 

 

 

 

 

 

 
Introduction Day 1 Day 2
Day 3 Day 4 Day 5

Last update: 23rd January 2002
Copyright © Dr G. Lloyd, School of Earth Sciences, Leeds University, 2002