From Earth Science On-Site
Apes Tor, Staffordshire
KEY STAGE 4 PREPARATION AND FOLLOW-UP IDEAS
© GeoconservationUK ESO-S Project, 2013
It is anticipated that the ideas and materials presented here will be adapted by schools, and others, to be more appropriate for their own purposes and programmes of study.
In such circumstances please acknowledge the source as the Earth Science On-Site project.
The underpinning knowledge and understanding of geological processes gained in KS3 should be revised with pupils. In addition the necessary Physics studied at KS3 of the response of materials to deforming forces needs to be revised and slightly extended.
These should form the basis of the preparatory lesson in school within a week prior to the field visit.
Part 1: the response of materials to bending forces (time: about 15 minutes)
In KS3, pupils are likely to have investigated the behaviour of springs and rubber bands when they are stretched. Under lower stresses, both show a linear relationship (known as Hooke’s law) between force (load) and extension. This is called elastic deformation. However as the stress increases, the behaviour of the two materials begins to differ; neither obeys Hooke's law any more, but the spring becomes permanently deformed, while the elastic band becomes much more difficult to stretch further, and eventually snaps.
However, it is unlikely that pupils will have investigated behaviour of materials under bending forces. For the purpose of this preparatory lesson, a few quick qualitative demonstrations should be enough to achieve the following learning objectives:
- know that under low bending forces, a strip of material will exhibit elastic deformation;
- know that under higher bending forces, a strip of material will exhibit plastic deformation, becoming permanently bent;
- know that under very high bending forces, a strip of material may snap, suffering brittle fracture;
- know that some materials deform in these ways more readily than others.
For quick demonstrations the teacher will need to ‘sacrifice’ e.g. a few (old) wooden rulers (or wooden skewers), a few (old) plastic rulers (or similar plastic strips which do eventually show brittle fracture) and a few metal (steel) rulers (or similar metal strips which can be bent by hand). If a variety of metals in strip form such as copper, zinc, aluminium, are available for comparative purposes, so much the better. A steel wire coat hanger could be used to show brittle fracture after ‘working’ in the plastic stage.
Finally leave the class with the (unanswered) question: is it possible to bend rocks in this way?
“Before we try to answer this on our field trip, let’s just remind ourselves of what we know about rocks…”
Part 2: revisiting KS3 geological processes (time: about 40 minutes)
In broad terms, KS3 ‘geological processes’ is the study of the ‘Rock Cycle’. Below is one possible approach to this revision making use of the rock cycle.
Consolidation of learning objectives from KS3
- be able to describe and explain ways in which rocks are weathered by physical processes (as distinct from eroded). In addition, pupils need to know that chemical weathering is also an important agent
- be able to observe and describe the key features of a rock specimen, including colour, texture and mineral content
- be able to classify specimens of common rock types, using observed features, as igneous, sedimentary or metamorphic, and name such common rock types
- be able to make reasonable suggestions as to how a common rock type they have described was formed, and how long the process took.
1. Weathering (10 minutes)
The use of photographs of real rocks that have suffered weathering could form the basis of a fairly brief question and answer session. Suggested images:
- boulder(s) showing onion-skin weathering
- boulder(s) split in half – e.g. Devil’s Marbles
- jagged, broken rocks on mountain ridges, preferably with patches of snow still visible.
An internet search brings up many possible images for classroom use
Some Internet images provide useful background discussion about the weathering mechanisms involved. An important general point emerges: there is rarely one weathering process operating on its own, but usually a combination of physical and chemical weathering processes. For the purpose of this revision lesson, the teacher simply needs to give the pupils in small groups one minute to come up with suggested causes of the weathering depicted in each image; it is the pupils’ suggestions and subsequent discussion generated that are important; there is probably no single ‘correct’ answer in any of these situations. If pupils do not suggest chemical weathering, the teacher may need to pump-prime the discussion by asking them whether chemical changes might be possible in any of these examples.
2. The rock cycle (35-45 minutes)
The remainder of the revision session could be based on the rock cycle. A simplified pictorial version of the rock cycle is used as the basis of the following activities. This can be downloaded by following the links from The Earth Science Education Unit
Provide a set of six common rock types (sandstone, shale, conglomerate, granite, dolerite/basalt with crystals just visible, slate or schist or gneiss). Tasks in small groups:
- agree key features of each specimen (colour, texture, etc), and whether sedimentary, igneous or metamorphic
- now provide a set of name labels; groups have to decide quickly which label belongs to each specimen, and be able to justify (for able groups, provide MORE name labels than specimens!)
- plenary agreement on correct labelling and why.
Provide rock cycle outline; agree where the weathering processes just revised would appear on the outline.
Teacher shows quick demonstrations, without commentary, of;
- sedimentation jar filled with water then 3 charges of different sediment (the last one being muddy to show slow fall of sediment)
- a volcano in a laboratory. This demonstration of a volcano uses wax and sand
Task for small groups:
- decide what part of the rock cycle outline each demonstration is modelling
- decide at which point in the rock cycle each specimen would have been formed
- agree on the rough timescale needed for each rock type to have been formed, including the difference, for sedimentary rocks, between time for deposition and time for a deposit of loose sediment to be turned into a hard rock, and also how that may happen.
Groups inspect set of sedimentary rock specimens (sandstone, limestone, shale). Ideally, more than one type of limestone should be included in the set. Plenary discussion of the identity of these specimens leads to revision of test for all limestones – action of dilute HCl acid. Finally agree where the formation of these rocks comes on the rock cycle.
How did sediment become hard rock? This can be modelled for a sandstone, as shown on the JESEI website
Following the field visit to Apes Tor, the knowledge and understanding of geological processes gained on the field visit needs to be consolidated and extended.
- consolidation of understanding of the processes by which rocks are deformed
- be able to relate this understanding to the general pattern of behaviour of materials under bending forces
- be able to deduce the time sequence of geological events from the pattern of observations made on rocks in the field
Reviewing the Apes Tor section
Each pupil is now provided with a definitive copy of the completed Apes Tor section exercise to compare with their own attempt, and to put into their notes. (A copy of this sheet is included with the notes for site F in document AT7 Ex F).
Deformation of rocks
Depending on how much modelling of folding and faulting was carried out at Apes Tor, the main part of this session could be devoted to modelling of these processes. Such modelling can be real or virtual using ICT packages.
Deducing a geological sequence
The Apes Tor section can now be used to deduce the geological history of the rocks at Apes Tor. This can be done as a small group activity, prompted by a sequence of questions. Alternatively, pupils could watch the 4 minute animation with narration “A short history of Apes Tor quarries”:
Please note: this narrated animation is an .exe file, and although this file is safe to download, some computer systems may prevent you from doing so. It is also very large (5.6MB) - please consider whether you want to download a file of this size.
Each pupil should be provided with a copy of the rock cycle to remind them of the processes and events involved.
In the table below statements 1 to 8 show the sequence of geological events beginning with the oldest. Teachers may want to refer to it when assessing pupils’ work.
|1. Layers of limey mud sediment were deposited.
||Deposits accumulated in a sub-tropical sea approximately 320-330 milllion years ago in the Carboniferous period.
(Shells made of CaCO3 provided the sediment from which limestone was made. Further from land the sediment was muddier and this provided the material from which shale was made).
|2. Sediment was buried below later sediments.
||Layers were buried below the sea floor, sediment was compacted and excess water was squeezed out.
|3. Sediment became hard rock and limestone and shale were formed.
||Grains of CaCO3 &/or mud were cemented together by more CaCO3.
(Limey shales and dark muddy limestones formed by this process of lithification).
|4. The limestone & shale were buried deep in the Earth and compressed.
||Typically sedimentary rocks become buried some 5-10km beneath the surface, but not much deeper as this would result in metamorphism.
|5. The layers of rock were folded.
||Compressional forces were generated by tectonic plate movements.|
East-west compressional forces produced the folding at Apes Tor.
Folding probably happened later in the Carboniferous period.
|6. Further layers of sediment were deposited and lithified.
||Probably during Triassic and later Periods.
|7. Layers of rock were uplifted.
|8. The layers of rock were weathered and eroded.
||It would have taken millions of years to remove all this rock.|
(10 000 years ago at the end of the Ice Age in permafrost conditions formed after the ice had melted freeze/thaw weathering formed angular scree material - the breccia at locality C)
|9. And finally …
||Humans mined and quarried the rocks and minerals in the valley and hillsides. (This is how Apes Tor became a set of abandoned small riverside quarries).
Further quarrying will not happen. (The site lies within the Peak National Park and has been incorporated into the Manifold Valley Site of Special Scientific Interest (SSSI)).
Further work on time sequencing
Further teaching and learning on the topic of sequencing geological events can be found on the Joint Earth Science Education Initiative website
Note to teachers
Homework answer for Apes Tor
C. Limey mud layers were deposited.
F. Layers were buried below the sea floor.
B. Limestone layers were buried deep in the earth and compressed.
H. Limey mud layers were compacted and water squeezed out.
E. Grains were cemented together and limestone was formed.
G. Limestone layers were folded.
D. Layers were uplifted.
A. Weathering and erosion took place.
The following poem may be helpful in giving students ideas for their homework.
Three fifty million years ago beneath an ocean deep
the sea floor at Apes Tor with sediments did seep.
The layers that were formed there were limeystones and shales
And the pattern was repeated over numerous cycales.(sorry about this)
Then the sediments were buried and the water was squeezed out
And the chemical cement flowed in and the rocks became quite stout.
Africa had been lurking to the south of our country
and when it bumped into us it pushed Apes Tor to the sky.(oops)
The force of the collision made the bedding planes to fold
because the temperature was much greater than when the rocks were cold.
Much later there was weathering and ice ages as well
and the surface was eroded as everyone can tell
The limestones were dug up to make building stones and walls
then the National Trust took over to make it safe for us to call.
Sorry about the rhymes, but maybe you can do better!
- ↑ www.geos.ed.ac.uk/undergraduate/field/holyrood/spheroids.html
- ↑ academic.brooklyn.cuny.edu/geology/leveson/core/topics/weathering/picture_gallery/display/new_jersey_garret_mt_1.html
- ↑ www.au.au.com/cameras/images/devils-marbles.jpg
- ↑ www.thewalkzone.co.uk/Lake_District/walk_36/180203h.jpg
- ↑ A simplified pictorial version of the rock cycle can be downloaded from www.earthscienceeducation.com/workshops/worksheet_index.htm
- ↑ Details are available at www.earthscienceeducation.com/workshops/rock_cycle/volcano.htm
- ↑ Modelling a sandstone - www.chemsoc.org/networks/learnnet/jesei/sedimen/index.htm
- ↑ see Joint Earth Sciences Education Initiative - JESEI - www.chemsoc.org/networks/learnnet/jesei/folding/index.htm)
- ↑ Sequencing geological events - www.chemsoc.org/networks/learnnet/jesei/sequenc/index.htm