Making a geological model from Sand!

Hi Everyone,

I’ve been doing job applications this weekend and frankly I’ve been getting very bored, so this afternoon I decided I would wash away the boredom with a fun little project which I’d always wanted to have a go at but never really had the guts to try out.

I made this gorgeous (if I do say so myself) little subsurface geology model from an old vivarium, some builders sand, some different coloured food dyes and some other coloured poster paint powder:

The completed model with labels

The completed model with labels illustrating the important features.

It’s the sort of thing you see in smaller museums all the time – although they are usually based on real sub-surface geology in a relevant area, while this one is completely fictional!

So how does one go about making this beauty? here’s a step by step guide:

1. Decide what geological/geomorphological features you want to show: for me this was to show three of Nicolas Steno’s laws of sedimentology – superposition, original horizontality and cross-cutting relationships – then I just added stuff as I went along like the channel fills and the scarp slope (good way to use up spare sand that one!).

2. Gather up your materials: I used mostly builders sand, but beach sand will do just as well, or if you really can go for broke… go find all the different colours of sand naturally. I also used a few other things from my model railway cabinet (ballast/mock coal/flock for the grass/lichen for bushes) – these of course are optional extras.

– pro tip number 1: don’t do what I did and use sand you found lying about in a bag in the garden… I had to rescue/evict many of my invertebrate cousins during the build!

3. Colouring your model: At this point you can either dye all your sand in different buckets or do what I did and dye it bit by bit as you go along. Either way will work but if you’re limited on sand, I recommend the latter strategy. The easiest dyes are poster paint powders as this keeps everything nice and dry, but food colouring works too. If you’re dying the sand, the ideal sand is the white sort you can buy in arts and craft shops.

4. Start laying down your strata: not much to explain here really. Though you might notice a couple of pyritised ammonites hanging out in my model…

5. OK, this is the complex bit: If you want to put in folds like the ones I have, you will need a piece of strong cardboard or wood, stand this vertically in the tank with enough space on one side to get your hand in like in the image below…

Using Cardboard for a false wall

Using Cardboard to enable the creation of folds or faults.

…now you build up your strata on side of the cardboard with more accommodation space and keep building until you’re ready to fold them!

– Pro tip number 2: in order to fault the strata, just use the cardboard to squash the sand from one direction. For folds, apply pressure to the top of the sand with your hand and also squash with the cardboard MUCH more slowly… I cannot stress that enough! This technique will result in awesome folds or thrust faults, I don’t know how to produce strike-slip or dip-slip ones… if you have an idea of how to do this, please share it in the comments box below!

– Pro tip number 3: the cardboard also allows you to put in a nice, easy dyke or other cross-cutting structure.

Now you’ve folded or faulted your strata, fill in behind the cardboard and fill the tank. I should say I didn’t invent this technique, I copied it from an old Open University video I saw many moons ago where the professor was attempting to explain folding and faulting using a massive sand-box model and a screw-and-plate piston, sadly I cannot find said video now.

15/10/2012 Update: While I still cannot find the OU video; This video from the Structural Geology RWTH-Aachen YouTube Channel gives you some idea of the process.

6. Unconformities: Are a doddle; just remove some of what you have done. In my case I used a strong piece of single (not corrugated) card. Then just continue placing strata on top (in my case at a jaunty angle… but it can be done the other way round)

7. The Surface: Lastly for the construction phase, add a layer of Flock (if you wish) and diorama-ize your surface layer! Lichen works for bushes. Trees, animals, buildings and people can be bought at any rail modelling supply shop, or online.

8. (For the Geology Nerds/Geologists): Have a ball labelling your gorgeous creation! Here are my three labelled sides for your amusement. I used PVA and printed labels alongside a permanent OHP marker for the annotations/symbols.

Faults side (Rear)

The rear side of my model, showing a few faults

The labelled left hand side of my model

The labelled left hand side of my model, showing two channel fills (one much harder to spot…)

The glorious, labelled front side of the model.

The glorious, labelled front side of the model. showing a lot of stuff..

When you’re done you can sit back and enjoy your handiwork, some people have said this would make an awesome coffee table… I think they’re right, get a nice glass top for it and you can be explaining geology to your in-laws over coffee in no time!

I hope you enjoyed this post and have fun making your own geological masterpiece! Share pictures in the comments, especially if you have some new ideas, or fix the strike-dip-slip faults problem!

Ben
07/10/2012

Edited at 21:36 on 07/10/2012: emboldened each point to make it easier to comprehend (hopefully)

3 thoughts on “Making a geological model from Sand!

    1. Benjamin Brooks Post author

      Hey mtb,

      Yes you do, see the paragraph after the two pro tips:

      “Now you’ve folded or faulted your strata, fill in behind the cardboard and fill the tank.”

      Sorry if it doesn’t read as well as it could or should, I put this together in something of a hurry.

      Ben

      Reply

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