MRT to magma chamber: field inquiry on plate
tectonics and the rock cycle at Little Guilin,
Singapore
Education and Outreach
INTRODUCTION
Field inquiry approach
This site and the suggested questions and activities below provide an excellent
opportunity for guided inquiry learning in the field. However, being in the field does not,
by itself, ensure that inquiry learning is taking place.
In inquiry learning, students pose questions, seek out relevant information, then
evaluate the information in an effort to answer the original questions (e.g. Margaret,
2003). In practice, inquiry is guided to varying degrees by the teacher, depending on
student prior knowledge, available time, and the complexity of the topic or available
information. To promote inquiry learning, answer student questions with guiding
questions rather than direct answers (Table 1).
Table 1. Possible teacher responses to a student who asks, "What rock is this?" Direct answers
(including confirmations of student guesses) inhibit inquiry learning, whereas guiding questions foster
inquiry learning.
Pedagogy
Didactic teaching in the
field
Inquiry learning in the field
Teacher role
Teacher as knowledge
dispenser
Teacher as guide and learning coach
Student role
Student as knowledge
recipient
Student as investigator
Teacher
responses to
the student
question,
"What rock
is this?"
• It's a norite.
• It's a norite, which is
high in iron and cooled
slowly underground
from a magma.
• See the coarse
mineral grains and
dark colour? Look
right there. That's
how you know it's a
norite, and that it
cooled slowly
underground from an
iron-rich magma.
• Tell me something about this rock.
• What colour is the rock?
• Can you see individual mineral grains
in this rock? What is their size?
• What does the colour tell you about
the composition of the rock?
• What does the grain size tell you
about how this rock formed?
• If a rock had a lot of iron, would it be
darker or lighter in colour?
• If liquid rock cooled slowly, would the
mineral crystals grow large in size?
• Where would liquid rock cool more
slowly - deep underground or on the
Earth's surface?
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Field learning lends itself to an inquiry-learning approach (Mogk and Goodwin,
2012). When the two are combined, students can benefit greatly. Field inquiry helps
students critically evaluate simplications and abstractions of natural systems that are
presented in textbooks and in the classroom (Stillings, 2012). Field inquiry also helps
students to form a more integrated, less compartmentalised understanding of natural
systems through both sensory experiences and the process of integrating observations
and concepts into a coherent whole (Mogk and Goodwin, 2012). In geography education
in Singapore, both the Ministry of Education and National Institute of Education are
advocating for field-based inquiry learning to become a standard component of students'
geography learning.
A key habit for inquiry learning is the practice of separating observations from
interpretations. Students might be tempted to leap immediately to the interpretation, "It's
granite!" Instead, guide them to start with describing what they see and using that
information as evidence to support their interpretations.
Student preparation
Students should already be familiar with:
• The rock cycle
• The processes that produce the three rock types (igneous, sedimentary, and
metamorphic)
• General physical features that distinguish the three rock types
• Rocks are made of minerals
• Minerals are crystals that occur in a range of sizes
• Isostatic adjustment: if significant erosion occurs, the lithosphere rises up in response
Logistics
The field site is walking distance from Bukit Gombak MRT (Figure 1). As a wellmanicured and easily accessible park, the risks are generally low. Students should not
climb on steep rocks, enter closed areas, or swim.
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
BUKIT GOMBAK SMRT
SITE1
SITE 3
SITE 2
SITE 4
North
0
100m
Figure 1. Location of field sites at Little Guilin. (Basemap from streetdirectory.com)
SITE 1: OBSERVING AND INTERPRETING ROCKS IN THE
FIELD
Learning objectives: Participants will be able to...
1a) Distinguish bedrock from loose soil/regolith.
1b) Distinguish fresh and weathered rock surfaces.
1c) Interpret whether rocks are igneous, sedimentary, or metamorphic
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Objective 1a) Distinguish bedrock from loose soil/regolith.
Here there are dramatic exposures of bedrock, which in geological terms means solid
rock that is physically connected to the rest of the crust. Note that "bedrock" does not
mean a particular rock type, only that the rock is connected to the rest of the crust. In
contrast, loose soil or regolith sits on top of bedrock but is not physically connected to it.
Find, sketch, and describe one example of bedrock and one example of soil.
If we break a piece of rock off of the cliff, is it still bedrock? Why or why not?
Are the cliff and pond natural or human-made features? What is the evidence?
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Objective 1b) Distinguish fresh and weathered rock surfaces.
Some of these boulders have heavily weathered surfaces. Other boulders have fresh
surfaces, which are much closer to the original colour of the rock. Find an example of
each and describe the evidence that indicates that the surface is fresh or weathered.
What are some processes that may have weathered these boulders?
Objective 1c) Interpret whether rocks are igneous, sedimentary, or
metamorphic
Students should already know the rock cycle and general characteristics of the rock types
(Table 2).
Table 2. The main rock types.
Rock type
Igneous
Common mode of
Liquid rock (magma or
formation
lava) cools and
crystallises
Common distinguishing
characteristics
Mineral crystals are
interlocking
Sedimentary
Rock particles (gravel,
sand, or clay) are
deposited and later
compacted and
cemented together
Grains of sediment do
not interlock; layers
might be seen
Metamorphic
A pre-existing rock is
changed by heat and
pressure
Mineral crystals align
and sometimes separate
into bands of different
compositions
"It's not the shape, it's what's inside." People tend to focus on the outward shape
of rocks. However, the outward shape does not tell us very much about the processes
that formed the rocks. Instead, focus students' attention on the materials and texture
within the rocks. As an analogy, if you wanted to know the taste of a new ice cream, you
shouldn't focus on whether the ice cream is in a bowl or in a cone - you should take a
taste to see what's inside.
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Are these rocks igneous, sedimentary, or metamorphic? How do you know? Sketch the
defining characteristics of the rock.
SITE 2: DESCRIBE AND INTERPRET ROCKS
Learning objectives: Participants will be able to...
2a) Describe and classify the rocks.
2b) Interpret how the rocks formed.
Objective 2a) Describe and classify the rocks.
How many distinct rock units are present?
For each rock unit, describe the grain size, grain relationships (interlocking or not?),
colour, and any characteristics of the minerals that you can observe.
Which rock unit has more iron and magnesium? How do you know?
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Objective 2b) Interpret how the rocks formed.
If liquid rock cools slowly, the mineral crystals grow large. If liquid rock cools quickly,
however, the resulting mineral crystals are too small to see without a microscope. Which
process would happen underground, and which process would happen in a volcanic
eruption onto the Earth's surface? Why?
Did this igneous rock cool slowly underground, or did it cool quickly on the surface after
being erupted from a volcano? How do you know?
SITE 3: INTERPRET GEOLOGIC HISTORY
Learning objectives: Participants will be able to...
3a) Interpret the relative ages of the Gombak norite and Bukit Timah granite
3b) Interpret the geologic history of Little Guilin.
Objective 3a) Interpret the relative ages of the Gombak norite and Bukit
Timah granite
Going back to Hutton and Lyell, the principle of cross-cutting relations holds that a
geological feature that cuts another is the younger of the two features. This is actually
quite a simple idea: by analogy, you have to bake a cake before you can cut it.
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Which is younger, the Bukit Timah granite or the Gombak norite? How do you know?
Objective 3b) Interpret the geologic history of Little Guilin.
Student questions
Develop a geologic history of Little Guilin by listing events from the oldest to the
youngest. Note where there is a gap in time in your history.
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Radiometric dating allows for estimations of absolute rock ages based on the decay of
radioactive isotopes since the time of crystallisation of the rock. Radiometric dating
studies of Singapore rocks provide estimated ages of 250-260 million years for the
Gombak norite and 230-245 million years for the Bukit Timah granite (Oliver et al., 2011;
and pers. comm.)
Are these dates consistent with the geologic history that you wrote above? What does it
mean about the period of erosion?
These rocks are how many times older than you?
These rocks crystallised from a magma more than 200 million years ago. At that time,
might this area have been found at:
Plate tectonic
setting
Yes, no, or
maybe?
Based on what evidence?
What additional information would
help to confirm or disprove this
hypothesis?
Collision zone
Subduction zone
Divergent
boundary
Transform
boundary
Hot spot within a
plate
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Based on your tectonic interpretation, what kinds of natural hazards would have been
common in the area that is now Singapore at about 230-260 million years ago?
SITE 4: CONTRAST JURONG FORMATION AND INTERPRET
AGE RELATIONS
Learning objectives: Participants will be able to...
4a) Describe rock at Block 503
4b) Interpret how the rock formed
4c) Hypothesise age relations between Little Guilin and Block 503
Objective 4a) Describe rock at Block 503
Describe the rock, including grain size, grain relationships, colour, and any other features
that you can observe. Note that the rock here is much less well exposed than at Little
Guilin; be sure that the features that you are describing are part of the rock itself.
Objective 4b) Interpret how the rock formed
Based on your description, what rock type is this? How do you know?
How did this rock form?
Questions? Comments? Please contact
Jamie McCaughey
[email protected]
Objective 4c) Hypothesise age relations between Little Guilin and Block 503
From our observations, is it possible to determine whether the Jurong Formation is older
or younger than the Bukit Timah granite and Gombak norite? Why?
If you could find a place where the contact between these rock units is exposed, what
evidence would you look for to know the correct age sequence?
REFERENCES
Lee, K. W., and Zhou, Y. (2009) Geology of Singapore, 2nd Ed., Defense Science and
Technology Agency, Singapore, 90 p.
Mogk, D. W., and Goodwin, C. (2012) Learning in the field: Synthesis of research on
thinking and learning in the geosciences, in Kastens, K. A., and Manduca, C.
A., eds., Earth and mind II: A synthesis of research on thinking and learning in
the geosciences: Geological Society of America Special Paper 486, p. 131163.
Oliver, G., Zaw, K., and Hotson, M. (2011) Dating rocks in Singapore, Innovation
Magazine, v. 10, no. 2, p. 22-25.
Roberts, M. (2003) Learning through enquiry: Making sense of geography in the key
stage 3 classroom: Geographical Association, 212 p.
Stillings, N. (2012) Complex systems in the geosciences and in geoscience learning, in
Kastens, K. A., and Manduca, C. A., eds., Earth and mind II: A synthesis of
research on thinking and learning in the geosciences: Geological Society of
America Special Paper 486, p. 97-111.
Questions? Comments? Please contact
Jamie McCaughey
[email protected]