As part of our Geography studies we have been looking at the life of a river, and how physical forces change its form along the course from source to mouth.
We have made models showing the classic features of rivers, including meanders, ox-bow lakes and deltas.
After watching a fascinating film of how water flowing round bends erodes the banks and carries the loose debris (load) along the river’s course (transportation), we decided to have a go at making our own working model of erosion at work, since even the smallest flow of water behaves in the same way as the mighty Amazon…..in theory.
After packing a paint palette with damp sand, pushing it down with our hands to make it hard, we tilted out tray and, with a pipette, squirted water onto a point in nthe centre of the top edge of the sand. Almost immediately, the water started to lift the sand, forming a hole down to the base of the palette (the river bed).
We continued to squirt water into the same point and watched as a channel formed. The continuous flow of water carried the loose sand away and curves began to form in the channel (meanders) as the water found the path of least resistance through softer sections of packed sand. Gradually the water undercut the banks which collapsed into the ever-widening channel, resulting in a gloriously messy fan-shaped mud bank at the bottom of the tray. Little channels formed through the wet mud in a perfect miniature delta!
We also experimented with a deep meander, using the water flow to erode its way through the “neck” of land and cut off the curved section to form an actual ox-bow lake as the river straightened itself out!
And all in the comfort of the classroom!
Everyone enjoyed the practical making of our own river system, watching the features appear before our very eyes, and all by just dripping water down a slope! It seems there is a lot of Geography to be learned by “playing in the sand”.
Wow looks like you had an amazing time I remember when I did this and it was really fun!
Hannah S Prep VI