Susan Derges, River Taw, 16 July 1997 and River Taw (Ice), 4 February 1997

Having been thinking a lot about working processes this week, the images that are rattling round my head are mostly ones made by following intriguing processes. In one respect, Susan Derges makes work using one of the simplest possible photographic processes: the photogram. But Derges’s work isn’t made in the darkroom but in the landscape. And these are photograms made on an ambitious scale.

Susan Derges, from the Full Moon series, 2003

Derges puts photographic paper into rivers at night and records the water and the life within it. In some more recent works, she superimposes a photographic image of the moon. The water moves – sometimes thanks to waves of different frequencies – weed floats; in some pictures there are tadpoles or ice.

This is nature recorded without a camera and it is fascinating.