The rocks here are sedimentary sandstone and volcanic. The layer of sediment have been forced upwards by continental collision as you can see in the first photo. The sand came from erosion of the nearby mountains, formed around 450 million years ago. At that time there was no vegitation and huge erosion from lightening and flash floods which created the sand. The second photo is of conglomerate, stones which have been washed into the sand during floods. You can clearly see the individual stones.