the fate of erosion products

The Victor Duruy high school is located in the Landes department, known in particular for its surfing beaches on the Atlantic Ocean. But students are often mistaken about the origin of the sand that forms our beaches, seeing it being pushed back by the waves. It will take levers to the brakes which are the temporal dimension (geological process of alteration, erosion, transport) and the spatial dimension (mountain range often far from the ocean). During a geological outing in the Pyrenees, we take sand from different sites along a river, up to the mouth of the river; each sample is numbered, and identified concerning the place of sampling. Back in high school, each group of students works on a sample: using a column of sieves, they will perform a grading of the grains taken: what sizes of grains are present? In what proportion? They can make a histogram of the proportions of each grain size. By comparing the results of the groups, they will thus be able to compare the future of erosion products along the watercourse. They can also observe the grains under a binocular magnifying glass to see their shape and appearance. They can also constitute a geologic model recreating the fate of the products of erosion from the mountain range to the ocean. On this model, zooms are made on the different sampling locations, with a Petri dish containing the grains of sand sampled.