Detailed Underground Mapping in a Mine - Learning to Think in Three Dimensions
|Originator||Colin Dixon (retired)|
|Department||Environment, Earth Sciences and Engineering (T H Huxley School), Imperial College, London, UK|
Part of a 2nd year Field Techniques course is a half-day exercise to make a cross-section on a scale of 1:50 of a dilated fault zone exposed in an old mineworking. The work is in teams and the result is assessed as a team. Success depends on accurate observation and recording by each member of the team and achieving a team consensus on the interpretation. Most students gain an insight into three dimensional thinking in this exercise and learn a great deal about working in a team in a very short time period.
Mapping in mineworkings, both surface and underground, has considerable advantages in enabling the student to appreciate the three-dimensional nature of geology. It complements the study of maps and seismic sections by being at a more detailed scale and giving hands-on (or eyes-on) access to the rocks and structures.
Students work in teams of four or five. The teams select themselves and thus the make up is social rather than related to geological interest or ability. The team is given a map and section which shows only lines on the National Grid and the locations of a number of stations which have been surveyed on the Grid. The task is to observe and record the geology in a vertical plane which passes north-south through the mineworkings at an easting shown on the map. There are four exposed parts of the section which cannot be seen from each other and thus simple surveying methods are necessary to locate the position of the section in the workings. The team is asked to produce an interpretation of the geology on the section. The scale is 1:50 and the section is only 10m by 10m.
Accuracy of observation and recording is variable. Perhaps one third of students record their observations the wrong way round because they become disoriented or their recording is insufficiently clear for others in the team to understand. Even if the students are told several times "look at your compass and find north" they still get disoriented. It is surprising that there is such a high proportion of the 18+ age group who succeed in finding north and then get east and west mixed up. It is noticeable that students with some experience at sea, have a much greater instinctive understanding of which way is west.
Teamwork is vital. It is noticeable that the best results come from one of two kinds of team. The first is the kind where there is a good 'team spirit' and everybody fits into a part of the task almost by instinct. For some reason, teams with a high proportion of women often fit into this category. The second kind is the team with a natural leader (usually male) who is willing to lead and the others are willing to follow. However, there are cases of teams with a natural leader who leads them into disaster. Teams with a natural leader have to be watched by the supervisor because there is a danger that those who are willing to follow learn little. What is very noticeable with almost all teams, is that in the space of two hours, the relationship between the members changes for the better.