Assembling 20 striking full-color photos for each title, Simon attempts to explain the hews and whys of landforms, tides, winds, and waves. The texts here are brief but not easy, introducing such specialized terms as ""gyres,"" ""tsunami,"" ""fetch,"" ""arroyos,"" ""playas,"" and more. Some essential information appears only on the endpapers: worldwide locations of deserts and the major ocean currents. Oceans provides colorful computer-generated maps to show El Nine, the dramatic warming of cool waters off the coast of Peru that causes sea life to disappear; however, the graphics, although beautiful, need more explanation to be readily understandable to the novice. The text of Deserts is less technical; the photos here of rusty, rippling sand dunes and majestically sculptured rock formations are visually appealing. Though their texts are not always clear, both books dramatically convey Simon's enthusiasm for earth's natural phenomena.