Glacial sand deposit. Sand is composed of small grains of rock. Its composition and grain size varies depending on the location, the rocks involved and the erosion and weathering forces that formed the sand. This sand has been formed by glacial action, and it referred to as periglacial sand. The clear grains of polished quartz were formed by the weight of the glacier grinding the grains against each other. This sand is from Cape Cod, near Provincetown, Massachusetts, USA.