Serious Sand Collecting and Geology post-16

A couple of years ago, my daughter brought a sand castle home from school.  She had visited the beach the previous week and collected some sand.  They had then mixed said sand with PVA glue and make a mini sand castle with a yoghurt pot.

When the PVA had dried out and gone clear, the castle was turned out and BINGO!! a permanent sand castle.

Scroll forward to the start of this academic year and the birth of a new obsession.  Sand Collecting!

The L3 Btec Applied Science, Unit 23 – Environmental Science module provides the ideal excuse for collecting and analysing samples.  Interestingly, there does not appear to be a large scale database of properties of sand from various locations round the globe.  So inspired, I’ve pointed my post-16 students in the direction of local and international  beaches to collect sand and generate some data.

The tests

Unit 23 requires learners to get to grips with albedo, soil horizons, angle or repose and a renewed acquaintance with the rock cycle.

What became apparent quite early in the teaching of this unit, was just how “difficult” it was to obtain teaching materials aimed at the correct level.  Obtaining a “quantity” of resources is easy – just Google “rocks” or “rock cycle” and there are literally thousands of hits – my difficulty arose from the rigour of these resources.  Btec L3 is an A-level equivalent course, and the majority of resources are suitable for KS3 or at a push KS4.

Sad days, but I guess this stems (in the UK at least) from the marginalisation of Geology as a subject – “is it Geography or is it Science” the politicians and exam boards ask.

Albedo

Thus inspired, I dug about until I came across Kathleen M. Gorski and her “bucket” albedo site, which I reworked into a paper I wrote especially for my Btec L3 - A simple method to determine surface albedo using digital photography  - this formed the basis of a Unit 1 assignment, where the learners are required to write a traditional academic paper.

Grain  Size Distribution

φ scale	Size range (metric)	Aggregate name (Wentworth Class)
−8 <	256 mm <	Boulder
−6 to −8	64–256 mm	Cobble
−5 to −6	32–64 mm	Very coarse gravel
−4 to −5	16–32 mm	Coarse gravel
−3 to −4	8–16 mm	Medium gravel
−2 to −3	4–8 mm	Fine gravel
−1 to −2	2–4 mm	Very fine gravel
0 to −1	1–2 mm	Very coarse sand
1 to 0	½–1 mm	Coarse sand
2 to 1	¼–½ mm	Medium sand
3 to 2	125–250 µm	Fine sand
4 to 3	62.5–125 µm	Very fine sand
8 to 4	3.90625–62.5 µm	Silt
< 8	< 3.90625 µm	Clay
< 10	< 1 µm	Colloid

The world of sand and rocks is filled with unusual, non SI units, which lead to a diversion to explore other scales and units.  Instead of working in m or mm, we found ourselves working in φ (-log2(diameter)) – a scale that goes more negative, the bigger the particle is.

However, I digress.

We used a series of graduated sieves (yet another non SI unit – MESH) to calculate the distribution of sands from Southerndown Beach (Wales)

 

 

 

 

 

From 100g of sand, we calculated the percentage in each fraction (as captured by the graduated sieves).  This then led into a major diversion to actually draw a graph and analyse the data.  Quickly rejecting Excel, we turned to GraphPad Prism as it allows the easy analysis of non linear regression (here I have overlaid and fitted a Gaussian distribution).

 

Angle of repose

Turning to angle of repose, we used the “pour to make a cone and measure the height / diameter” method >>here<<  Initially, our sand samples were insufficient to carry this out as a class, so we used gravel (obtained from Pets@Home – as fish tank gravel)

This led to a fascinating discovery of a database of materials and their angles (from a conveyor belt manufacturer) when we tried to compare our results to established data.

 

The big picture

Having dipped my toe into the world of sand and aggregates I am genuinely surprised that there isn’t more published data on the beaches of the world.  Yes people collect sand: International Sand Collection Society and the community activley swaps sand.  But – there is no published data on a wide scale covering albedo, grain distribution and albedo – let alone chemical composition.

So – that’s what I’ve challenged our Sixth form to create — the database of world sands!!  Watch this space for a website soon.

What I love…

About being a teacher, is that a potential 1hr teaching sequence on the environment has become a source of new learning for both the students and the teacher — and the potential to actually research something that’s not in the public domain.

What could you research and share with the community?