3D Spatial Skills Amongst Second Year Undergraduate Structural Geology Students

Jonathan Imber, Ken Mccaffrey, and Bob Holdsworth
Structural Geology Group, Department of Earth Sciences, Durham University, Durham, UK

Abstract

3D spatial skills are central to all undergraduate geoscience degree programmes. Most Year 3 or 4 geoscience students in the UK are required to complete an independent geological mapping dissertation. The dissertation implicitly or explicitly assesses the student's 3D understanding of their mapping area. Our aim is to present a case study of how male and female students in Year 2 of their undergraduate degree programmes at Durham University, UK, observe, interpret and draw three-dimensional geological structures. Year 2 students have undertaken basic training in field work, geological map interpretation and cross-section construction. Analysis of Year 2 performance therefore provides a check on the effectiveness of basic training in 3D thinking prior to the independent mapping dissertation. We deliberately focus on field-based observations and their representation in pictorial form (sketch cross-sections and/or block diagrams) because most Durham undergraduates are not introduced to workstation-based interpretation of sub-surface data until senior level (Years 3 or 4), if at all. The justification in the context of this Hedberg Conference is that understanding how geoscientists acquire and develop 3D spatial skills at an early stage may assist effective design and delivery of later, more advanced (e.g. industry) courses.

The case study focuses on a coursework assignment that forms part of a Year 2 module, "Structural Geology and Tectonics", and tests students' ability to interpret and sketch structures in 3D. This module is compulsory for students following the Geology and Geophysics with Geology programmes, typically attracting between 70-85 students per year. The assessment has run for 6 years, providing a sample of 478 assignments completed by 170 female and 308 male students, respectively (i.e. 36% female, 64% male). The assessment involves a 1 day field trip to examine coastal exposures (ca. 500 m long by 100 m wide at low tide) of a folded and faulted sedimentary sequence at Scremerston, Northumberland, UK. Students are required to describe the structures, measure and record structural data, construct a cross-section or block diagram and interpret the structural history. Results are presented as a scientific poster, which is marked on the basis of the following categories: (1) observations and data analysis (35%); (2) interpretation and structural history (35%); (3) cross-section and 3D understanding (20%); and (4) presentation (10%).

The mean overall score for all assignments (± 1 standard deviation) is 65% ± 10%, with mean scores of 65% ± 11% and 64% ± 10% for female and male students, respectively. The mean scores for the separate categories were: 67% ± 11%, 65% ± 12%, 58% ± 14% and 65% ± 10%, for the mark categories observations and data analysis, interpretation and structural history, cross-section and 3D understanding and presentation, respectively. One-way analysis of variance (ANOVA) taking mark category as the factor reveals a significant difference in mean category mark, F (3, 1908) = 49.5, with a probability < 0.01 that the mean values are in fact equal. Post-hoc analyses were performed using the Scheffé post-test to identify exactly where significant differences exist. The analyses show that the mean mark for the cross-section and 3D understanding category differered from the mean marks for observations (F (3, 1908) = 43.2), interpretation (F (3, 1908) = 26.6) and presentation (F (3, 1908) = 24.5), with a probability < 0.01 that the mean values are in fact equal. No other differences were found between mean scores at this confidence level. Furthermore, 10% of students either failed or achieved the minimum pass mark (40%) in the cross-section and 3D understanding category, compared with only 2.3% of students who either failed or achieved the minimum pass mark for the assignment overall. These results suggest that students' performance in the cross-section and 3D understanding category is lower than in the other categories, and that the overall mark may conceal relatively poor 3D spatial understanding of the studied outcrop.

The mean scores for females and males in the cross-section and 3D understanding category were 57% ± 14% and 59% ± 13%, respectively. Of the 49 weakest students who either failed or achieved the minimum pass mark in this category, 35% are female and 65% male. In this case, taking expected frequencies of 36% female and 64% male, χ² (1, n = 49) = 0.036, so the probability that the proportion differs from the overall ratio of male to female students is < 0.001 (lower-tail one-sided test) and the observed ratio reflects the gender balance of the sample as a whole. By contrast, of the 102 students who achieved the highest marks (≥ 70%) in the cross-section and 3D understanding category, 27% are female and 73% male. In this case, taking expected frequencies of 36% female and 64% male, χ² (1, n = 102) = 3.2. The probability that these results are the same as the overall ratio of male to female students is < 0.10 (upper-tail one-sided test). This result compares with the 37% of females and 63% of males who achieved an overall mark of 70% or more. In this case, taking the same expected frequencies, χ² (1, n = 172) = 0.029. The probability that these results differ from the overall ratio of male to female students is < 0.001 (lower-tail one-sided test). These results suggest that any gender difference in 3D spatial understanding may occur amongst the highest performing students, rather than across the entire range of abilities.

This preliminary study to raises two issues. (1) We need to understand the reasons why students tend to perform relatively poorly in 3D spatial understanding, in comparison with other geoscientific skills. We need to apply this understanding to raise the general level of 3D spatial skills among Year 2 students. (2) We need to investigate the reasons for the apparent gender difference amongst the highest performing students and apply this understanding to develop strategies that enable the highest perfoming female students to excel at 3D spatial understanding. Our findings may be significant in that some of the most able female geosciences graduates may go on to join the hydrocarbon industry. This work will require collaboration with cognitive psychologists and computer scientists with expertise in 3D understanding, perception and visualisation.

AAPG Search and Discovery Article #120140© 2014 AAPG Hedberg Conference 3D Structural Geologic Interpretation: Earth, Mind and Machine, June 23-27, 2013, Reno, Nevada