The title was too tantalizing to resist. I just had to go check out the Internet for further information on the marvelous sandstones of Paria Canyon in northern Arizona, also called “The Wave,” according to the article, “Richland man sees sandstone proof of global flood” (The Daily Astorian, Jan. 3). I found several great websites and some super photos.

Many will recognize the place. Even for a color-blind geologist like me, the vermillion color of iron oxide in the sandstone is brilliant, clearly deposited by groundwater. The rhythmically laminated bedding dips in a wide variety of directions, forming graceful swoops, the result of various wind directions blowing sand about in an arid desert environment; each layer deposited in hot wind, grain by grain, in a sand sea like the Sahara Desert. Even salt crystals from evaporated water can be found in these beds, an indication of prolonged desert heat.

A key clue to identifying the dune environment are horizontal seams of sandstone that mark the deflation plain, where the dunes blew away to the water table, leaving a wet sheet of sand. There were oases in that great sand sea, and dinosaurs may have slaked their thirst there. Sands beneath the water table could not blow away and so were protected.

More sands eventually blew in, forming more cross beds that buried and protected the deflation layer. The land was slowly subsiding as the sands blew through, and, over millions of years, this allowed great thicknesses of desert dunes to drop beneath the water table to be preserved. Now these sands are cemented into hard layers, and have been uplifted as mountains, eroded by flash floods and sculpted by desert windstorms.

Tsunamis did not deposit the Paria Canyon sandstones. Tsunami deposits are rarely more than 12 inches thick, let alone 100 feet or more. They form horizontal sheets, not swooping festooned cross beds.

Great floods usually deposit poorly sorted gravels and scour the underlying ground. The 14,000-year-old Missoula Floods left cross-bedded gravels dozens of feet thick in northeast Portland, where the 800-foot deep waters burst out of the Columbia Gorge and slowed, dropping their sediment load.

In the extreme, 105,000-year-old boulder layers, 30 feet thick, on the island of Lanai, were dumped by a 1,200-foot high tsunami, when cubic miles of the west flank of the Island of Hawaii fell off into the abyssal depths. Paria Canyon is not like this at all.

These occurrences and others are described in “The Sedimental Consequences of Convulsive Geologic Events,” a compendium of research papers available online from the bookstore of the Geological Society of America, a good read for open-minded Young Earthers. Highly recommended.

TOM HORNING

Seaside