This is good observational science, backed up by experiments in a wind tunnel. The book progresses from the smallest scale : 'The Physics of Grain Movement', through 'Small Scale Effects' to 'Large Scale Effects'.
The plates are alas in black and white, illustrating fairly primitive experimental equipment of the time, and natural phenomena, mostly in the Libyan and Arabian deserts.
The mathematical modelling is relatively straightforward, but modern researchers, such as those at the University of Chicago and California Institute of Technology, have developed Bagnold's concepts immensely, and even challenged some of his tentative conclusions on 'singing sands'.