Desert Magazine (index), December 1963, pages 10-11, (703kb pdf)

by Vern Miller

No one was more astonished than long-time Nevada resident Vern Miller to discover that formations he'd always known as "tufa," were not really tufa at all.

Spotted throughout the Great Basin of Nevada are beds of "rock" formations which appear to have been formed the same way that the Great Barrier Reef of Australia was formed . . . as coral at the bottom of the sea.

And well it could have been so, for the entire Great Basin of the western states once formed the ancient bed of the prehistoric Lake Lahontan more years ago than you can count on your fingers, even if you take a hundred thousand years per finger.

The tuffs, however, which have erroneously been called tufa by many authorities for a great number of years and still today are called so by the majority of Nevadans, came from volcanic action that took place those many years ago when the Great Basin was still a sea. These are being eagerly sought by rock hunters and rock garden enthusiasts today.

The material in these tuffs, according to the latest scientific authority, erupted from the magma zone thousands of feet below the surface as fine ash and pellets. These were carried by the high winds sometimes for many miles before settling to earth. Others fell nearby, close to the eruption.

As they floated into water, such as that contained in Lake Lahontan, they settled to the bottom and mingled with the normal sediment. In addition, ash falling on bare land was later washed into lakes by rains and streams. Ashy clays and sands thus produced were converted into tufaceous shales and sandstones. The larger pellets formed the blobs that are now called tuffs.

Volcanic ash tends to travel far while pellets or the coarser ejected materials fall near to the source. Because of this, tuff varies a great deal in texture as well as chemical and mineralogical composition. It also varies in appearance from white to a dull brown and in several shapes.

Generally, the material ejected is usually thought of as fine ash or small pellets. Actually, some were much more than pellets. They were chunks ejected into the air which met and adhered to one another in midair and plunked to the surface of the earth in huge blobs.

Such large chunks are found in central Nevada in the Pyramid Lake region about 38 miles northeast of Reno and along U. S. Highway 40, starting about eight miles south of Lovelock and extending about six miles along the desert valley floor. This area is known locally as the Giant Tufa Park and a highway marker indicates the location.

While locally they are referred to as tufas, they actually are tuffs, formed from volcanic action. "Tufa" is a name properly applied to the cellular deposits from mineral springs or waters, either siliceous or calcareous. The latter is called "calc tufa," and is a cellular variety of calcite in which the mineral matter has been deposited from the waters of springs. In the past, mineralologists have included these formations along with tuff. However, this theory is no longer sanctioned.

Prime example of tufa formations are the stalagmites and stalactites found in caves throughout the country, formed by the dripping mineral waters within those caves. There is little to indicate that the Nevada "tufas" were formed by this action, although materially tuffs and tufas are similar.

Small tuffs are found under desert sands, one type resembling toadstools. Resting on the desert floor, they vary in depth from the surface to several feet below. The ones most easily available to hunters of specimens are those easily spotted on the surface, such as a field of toadstool tuffs located near Henderson on Nevada 41.

These make an exotic addition to decorative rock gardens. It is quite an oddity, however, that they are rarely, if ever, located near the beds of giant tuffs which may reach the proportions of a four-story apartment house. The mushroom variety ranges from the size and weight of a marble to five feet in diameter, often weighing 400 pounds.

One of the most sought after areas in the realm of tuff hunting is the Lahontan Valley of central Nevada whose center is the city of Fallon. Located sixty miles east of Reno, the northern portion of the valley contains many of the mushroom type of tuffs. Part of this area is known as the Forty Mile Desert, the Nemesis of pioneers a century ago who crossed it in covered wagons. It is more accessible now, however, being crossed from north to south by black-topped U. S. Highway 95.

This area is reached from Reno by traveling on U. S. Highway 40 to Fernley. The remainder of the distance into Fallon is traveled by U. S. Highway 95 alternate. The entire portion of the valley to the north of Fallon contains the Carson Sink and portions of the Forty Mile Desert. In this desert wasteland, numerous mushroom type tuffs are located.

Other tuffs small enough to be retrieved from the desert floor, while they may vary slightly to those found in central Nevada, are located in almost every one of the desert valleys stretching from Black Rock Desert south to Las Vegas and nearby Henderson.

For those interested in rock formations that lend themselves to exotic camera work, the giant tuffs of Pyramid Lake are readily accessible from Reno. Adjacent to both shores, giant tuffs tower over a hundred feet into the air.

A short drive around the southern end of Pyramid Lake places the tuff hunter in the Indian reservation town of Nixon, one of the headquarters for Nevada's Paiute Indians. Here the driver may turn north on State Route 34 and within ten miles is traveling along the western shore of Winnemucca Lake, a dry lake bed that is completely surrounded by more giant tuffs.

This dry lake bed reveals yet another form of tuff - sheets of tufaceous material similar to the thin shale of the desert's sandy areas, only greater in thickness. Often mistaken for tufa formed by mineral water action, this tuff material so closely resembles coral that unless an individual knows differently he would surely identify it as such. Found protruding in small sheets it, too, adds much to rock gardens and table centerpieces.

There is no need for rock hunters to chip away at giant tuffs and destroy their beauty in order to obtain a specimen, as smaller counterparts abound in the areas mentioned above.

To uncover and retrieve mushroom tuff specimens, only a sharp pointed shovel is necessary. This implement may be used to dig sand away from the tuff's edges and is strong enough to pry a weighty specimen from its sandy bed. Sometimes a pry bar is useful in locating underground tuffs, as it may be easily poked into deep sand.

Special transportation is unnecessary, as desert roads in most of these regions may be traveled by passenger car if the driver takes care in avoiding soft sand. Those who conduct their search in a 4-wheeler, however, operate at an advantage - especially when one of the larger tuffs is uncovered and the vehicle may be driven to the site.

For a day's outing, tuff hunting is hard to beat. Carry along a good picnic lunch with plenty of water and the whole family will have a "tuff" time!