It鈥檚 enough to impress even a geologist鈥擱ichard Waitt, for instance.
Waitt, who is with the US Geological Survey in Vancouver, Washington, has
visited the Scablands hundreds of times to trace the story of the megafloods
through the record preserved in sediment. 鈥淚鈥檝e been around this stuff for many
years,鈥� he says, 鈥渂ut there鈥檚 still places I go sometimes and, you know, my jaw
just drops. It鈥檚 just so huge.鈥�

Like grand opera, the tale of the megafloods is replete with exotic
adventures and tragic heroes. It all started in the 1920s, when a geologist from
the University of Chicago named J Harlan Bretz concluded that the overblown
topography in the Scablands was created by a sudden deluge, not the slow,
uniform processes of erosion and glacial scouring. Scenting the unfashionable
odour of catastrophism, many of Bretz鈥檚 colleagues turned their backs on the
flood. Exit martyred hero, stage left.

But not for long.

By 1940 Bretz鈥檚 ideas had won the day, after a USGS geologist named James
Thomas Pardee supplied the missing piece of the flood story. Near Missoula in
western Montana, Pardee found ripples on an ancient lakebed just like the ones
that form on streambeds, but of absurdly large proportions: 15 metres high and
hundreds of metres long. Only a staggering flow of water could have made
them.

Thanks to these pioneers, the full story of the Missoula floods began to take
shape. At the end of the ice age, a lobe of the vast Cordilleran Ice Sheet oozed
into the gap between two mountains near the present-day town of Sandpoint,
Idaho. A deep lake of meltwater formed behind the frigid dam, filling several
valleys in Idaho and western Montana. This piece of geography, now just a fossil
lakebed, is known as glacial lake Missoula. Pardee estimated that the lake once
held as much as 2500 cubic kilometres of water, the equivalent of Lake Ontario
and Lake Erie combined. If you gaze up the valley slopes from downtown Missoula,
you can still see parallel lines marking ancient shorelines carved by windblown
waves. The highest line stands 600 metres from the floor of the valley.

Then, some time around 15 000 years ago, the dam broke.

Studies of modern ice-dammed lakes give us some idea of what probably
happened. Glacial outburst floods, known as j枚kulhlaups, occur when the
water rises to about nine-tenths of the height of the dam. At that point the ice
barrier becomes slightly buoyant and rises a bit from its mucky foundations.
This allows water to insinuate itself underneath and drill tunnels through the
ice. 鈥淎t first this is only a trickle, but once the flow is established the heat
from the water enlarges the incipient tunnel,鈥� Waitt explains. 鈥淭o get from a
trickle to a reasonable flood can take weeks.鈥�

When the tunnel is big enough, the dam caves in. Lake Missoula spilled out
onto the lowlands in a rumbling, frothy flood peppered by chunks of the
shattered ice dam. Surging into the Spokane Valley, the waters headed west. At
the southwest corner of the present-day Scablands, the flood water pooled,
forming another large lake before it drained into the Columbia Gorge and then
into the sea. The whole Noachian spectacle probably lasted only a few days.

The surging waters carved landforms unlike anything else on the continent. As
Bretz remarked, the Scablands are aptly named, for they represent an unhealed
wound in the skin of the Earth. The waters scoured off the soft, windblown soil
near the surface and eventually reached bedrock, the hardened lava of the
Columbia Plateau.

Where the water cascaded off precipices in cataracts and crashed into the
rock below, it scoured out vast pits several kilometres wide called plunge
pools. In the northern tract of the Scablands, the water cut backward into the
rock and carved the Grand Coulee, a gorge twice as high as Niagara鈥檚 and several
times wider. Down in the Columbia River valley, the waters piled up gravel and
other debris into ridges as big as battleships. There are hundreds of them in
the Scablands.

In making sense of this histrionic landscape, Bretz and Pardee also left many
puzzles unsolved, including the question of how many floods there were.

In 1977, Waitt found evidence of dozens of floods in the Scablands, at the
very least. Poking around in a canyon in the Walla Walla Valley of eastern
Washington, he found 39 stacked layers of sediment deposited by water. Some of
the layers showed unmistakable evidence of multiple deluges: volcanic ash that
had rained down on one flood-borne layer before being covered by the next; also
rodent burrows dug through the lower reaches of the formation and then filled in
by later floods.

Similar formations on the Columbia River suggest there may have been as many
as 100 floods. Waitt estimates that about 25 of them were on a Noachian scale,
though some other investigators think only a handful were in that class.

Meanwhile, unknown to the Americans, Russian geologists were finding the
footprints of megafloods in Siberia. Not long after the Soviet Union collapsed,
an American geologist named Vic Baker went over to take a look. Earlier, in the
1970s, Baker had used a computer model to prove that the floods Bretz proposed
were physically possible and mighty enough to have carved the Scablands.

Baker, now at the University of Arizona in Tucson, confirmed what the
Russians suspected: megafloods had occurred in Asia, too, when its ice sheets
retreated. In fact, an ice-dammed lake in the Altay Mountains had released
deluges of comparable scale to the Missoula floods. Other floods also happened
at the margins of all the major northern ice sheets鈥攖he Laurentide and
Cordilleran in North America, and the Fennoscandian and Eurasian sheets on the
other side of the Atlantic.

How could geologists have overlooked such an important process for so long?
Perhaps because, as they scurried around like ants in exaggerated landscapes, it
was hard for them to get the big picture. 鈥淵ou go out there in the field,鈥� Waitt
says, 鈥渁nd once you get your eyes adjusted to the colossal scale of things you
are just astonished.鈥�

HERDS of cloned farm animals could be a common sight within a few years,
following a breakthrough by the American company ABS Global of De Forest,
Wisconsin. The company has developed a technique for mass-producing clones. Last
week, it showed off its first success, a six-month-old calf called Gene.

Gene was created from a cell removed from a fetal calf. But the process works
just as well with the cells of adults, says Michael Bishop, ABS鈥檚 director of
research. This is important because it allows the cloning of animals that have
proved their worth. More than 10 clones of adult cattle have been implanted in
cows and are due to be born over the next few months. Earlier this year,
Scottish researchers revealed that they had cloned Dolly from the cell of an
adult sheep (This Week, 1 March, p 4).

To make their clone, the ABS team took a cell from the donor animal and fused
it with an unfertilised egg that had its nucleus removed. The egg developed into
an embryo with the same genes as the donor cell. The team then divided the
embryo into individual cells and grew these into new embryos before implanting
them in surrogate mothers.

Although ABS won鈥檛 release details of its new process pending patents, Bishop
says the key breakthrough was establishing a 鈥済enetically stable鈥� cell line to
serve as the basic stock for cloning.

In 1994, Neal First of the University of Wisconsin in Madison cloned cows
using the cells of a developing embryo. But there is a limit to how many clones
can be produced this way. When the team at the university cultured more than a
few thousand copies, the cells began to accumulate genetic flaws. ABS says it
has found a way to prevent or repair those flaws. 鈥淭hese cells can be used to
make unlimited numbers of exact duplicates of the animal that they are derived
from,鈥� says Bishop.

Bishop also claims a high success rate. Half the embryos implanted in
surrogate mothers resulted in pregnancies. To date, 80 per cent of the
pregnancies have passed the critical 90-day milestone in the cows鈥� 10-month
gestation, after which the chance of miscarriage drops significantly. By
contrast, Dolly was the only success out of 277 implanted embryos.

Marc van鈥檛 Noordende, chief executive of ABS Global, says the technology has
enormous potential for the cattle-breeding industry. Cloning would enable cattle
and dairy producers to maximise the benefits of desirable traits, such as high
milk production or tender meat.

The new process could also speed the development of genetically engineered
cows鈥攆or example, those that produce pharmaceuticals in their milk.
Techniques for adding new genes to an animal鈥檚 chromosomes have a success rate
of one cell in a thousand. Performing it on millions of clonable cells at once,
says First, could vastly increase the number of successes.