Earth and Environmental Science 11–12 · Year 12
Strike, dip and the order of events at an outcrop or road cutting (fieldwork)
Module 5: Earth’s Processes
School laboratory, not for home
In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
The idea
Beds are laid down close to horizontal, so a steep measured dip records tilting or folding that came after deposition; with superposition, cross-cutting relationships and unconformities, strike and dip readings put the events at an outcrop in order.
Safety card
Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
Hazards
- traffic at road cuttings
- rockfall from loose faces
- wet rock platforms and tides
Controls
- work only on the verge side of a barrier
- helmets at quarry faces
- check tide times
- no hammering without eye protection
Note
Fieldwork: complete the school's excursion approval and a RiskAssess field risk assessment under NSW Department of Education procedures; any test reagents carried into the field fall under the Chemical Safety in Schools (CSIS) package, Section 1.
What you need
- compass-clinometer (or a phone clinometer app plus a magnetic compass), field notebook, hand lens, tape measure
- a safe outcrop: a road cutting with a wide verge, a coastal platform at low tide, or a quarry face by arrangement
- do-it-yourself dip and strike model (Earthlearningidea) for practice beforehand
How to do it
- Practise on the model: place the clinometer along the steepest line on the bed for dip and along the horizontal line for strike.
- At the outcrop, choose three bedding surfaces at least 5 m apart; for each, measure strike (bearing) and dip (angle and direction) twice.
- Sketch the face with a scale, mark the measured beds and note grain size, colour and any fossils.
- Record any fault or unconformity and state which is younger using cross-cutting relationships.
- Plot strike and dip symbols on a base map, describe the structure (uniform tilt, fold limb, horizontal) and write the sequence of events: deposition of the beds from oldest to youngest by superposition, then tilting or folding, then any fault or unconformity that cuts them.
What you should see
Repeat readings on the same bed agree closely and their spread is reported; beds of one tilted sequence give near-identical values along the face, while a change of dip direction across the outcrop marks a fold axis. Because bedding is laid down close to horizontal (the law of original horizontality), a steeply dipping bed records tilting that happened after deposition. A sketch with three measured beds, a stated structure and a sequence of events ordered by superposition, tilting and cross-cutting relationships is the deliverable.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Beds were deposited tilted.
- Dip is measured in any direction along the bed (it is the steepest line).
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES12-12EES11/12-5EES11/12-6EES11/12-7
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-12-01
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.