Extraterrestrial objects colliding with Earth can cause dramatic changes to the planet and affect the course of evolution.

Two CSM professors travel to a remote Siberian outpost to study a 35-million-year-old crater.

The break-up of the Soviet Union has brought a boon to science in the form of more open access to once-secret sites.

About 35 million years ago, an extraterrestrial object struck what is now the region around Popigai, Siberia. The impact instantaneously created a 60-mile-diameter crater and industrial-grade diamonds.

When the diamonds were discovered in modern times, the area was closed to outsiders in the event the diamonds might prove valuable some day.

But economic hard times have hit much of the former Soviet Union and today, tourist (and scientist) dollars are more valuable than diamonds.

Two geology and geological engineering professors, John Warme and Keenan Lee, traveled to Siberia this summer to study the Popigai impact site, an area rarely seen by Westerners. Studying the phenomenon of extraterrestrial (comet or asteroid) impacts on Earth furthers our knowledge of how they have shaped the planet and affected life.

Understanding impact crater morphology on Earth can also help us learn more about Mars. Its craters can also be studied and scientists will be able to tell if the planet once had water. If it did, the chance of Martian life is more likely.

The earth has been bombarded by objects from outer space since the beginning of time. Some impacts, such as an object that hit the Yucatan Peninsula in Mexico 65 million years ago, are believed to have caused mass extinctions, most notably of the dinosaurs. There have been many others.

Although the chances of a collision taking place on any given day is in the hundreds of millions to one, given millions of years of geologic time, such events must have occurred in the past and will occur in the future.

It’s something humans think about. Deep Impact, a movie about a comet colliding with Earth, depicts Hollywood’s idea of such an event. (In the movie, a lot of people die.) "I don’t know if it would actually look like that," says Warme, "but it certainly would cause that kind of destruction."

In January 1990, Warme and several students were working in the mountains of Nevada and noticed a rock anomaly that Warme believed could only have been caused by a catastrophic event such as an extraterrestrial impact. He has been studying the site ever since.

The Alamo Breccia, a fragmented carbonate rock now found in the mountains about 100 miles north of Las Vegas, Nev., is composed of pieces of lagoon sediments and fossils, typical of an ancient shallow ocean.

Of many plausible explanations for such a disturbed mixture, the only one that has withstood scientific analysis is an impact by a comet or asteroid, which occurred about 365 million years ago and created the Alamo Breccia over the course of a few hours or days.

The object itself was probably fairly small, only a few kilometers in diameter, says Warme, and no mass extinctions coincide with the collision. But the geography of the region changed dramatically.

The geological record indicates that eons ago, a deep ocean covered the area. At ocean’s edge, a lip of land created a lagoon filled with coral and marine animals. It appears that an extraterrestrial object crashed onto Earth near where the lagoon met the ocean and created a series of tsunamis and related water spouts that churned up the terrain.

Most significantly, the Breccia contains shocked quartz from the impact, carbonate spherules from the vapor cloud that was created, and iridium from the projectile itself. In the millions of years since the impact, tectonic plates shifted, mountains moved and the landscape was repeatedly altered. Today, evidence of the impact can be found in 15 different mountain ranges, now separated by desert valleys.

"Studying this impact site is a lot like putting together a three-dimensional puzzle," says Warme. "We’re putting mountains and strata back to where they started."

Learning more about impact sites in general and the Alamo Breccia in particular furthers our understanding of the development and evolution of Earth. "Documenting an impact site helps put the event into a time frame so scientists can have a better idea of the frequency of such events," explains Warme. "Paleontologists use the information to help understand how extinctions occur." Do life forms gradually become extinct on a regular basis or do occasional physical events cause extinctions in a dramatic fashion?

The Alamo Breccia is an especially good impact site to study because it is in the desert and well exposed. "It can tell us what to look for at sites that are not exposed [such as those in forests or jungles]," Warme says. "Alamo Breccia can be used as a model for discovering new sites."

To learn more about what to look for at impact sites, Warme and Lee traveled to Siberia in July to study the Popigai crater.

Three parts make up that crater deposit, says Warme: breccia, dense melted rock (tagamite), and less dense ashy rock (suivite). Studying the much younger Popigai crater gave Warme the chance to see the proper relationship between these parts, and then return to Nevada to look for those same relationships. "In the Alamo Breccia, there’s more disintegration and alteration, so although I’d seen the parts, I didn’t recognize what the original relationships were," he notes.

Lee wanted to study the Popigai crater in order to be able to compare it with the object of his research, an impact site in Tunguska, Siberia (See Mines Magazine, November/December 1998 issue for more details). What occurred in Tunguska in 1908 is still unexplained, though many believe it, too, was caused by an extraterrestrial object.

The professors’ trip to Popagai began with a flight to Moscow, followed by a 4½-hour flight to Krasnayarsk, half way across Siberia.

Despite the reasonable cost, Warme says the trip was first class and well organized. While in Krasnayarsk—a surprisingly sophisticated city of 1 million—they were treated to feasts of champagne, vodka, caviar and deliciously prepared food served on linen tablecloths.

Warme and Lee were part of a group that included seven other Americans (two of whom were simply tourists), and a Russian support staff, including a variety of scientists, a geologist guide, an expedition coordinator and an expert cook.

From Krasnayarsk, the group flew northward to Khatanga, an outpost built on permafrost north of the arctic circle, headquarters of a Russian polar expedition that assesses the resources of the region.

From Khatanga, the group was transported by helicopter to camp at a crater site along the Rossoca River across from the breccia pictured on the front cover.

They camped along the banks for several days and explored the area during the 24-hours-of-sunlight days. The next stop was the nearly abandoned town of Popagai, where just one family of fishermen lives during the summer months. The group reached it by floating, paddling and lugging rubber life rafts about 20 miles downstream.

While at the sites, Warme collected geological samples, something unheard of for foreigners in the past. "I shared the samples with a geochemist friend, Philippe Claeys, at the Geochemical Institute at the famous Berlin Museum of Natural History," Warme says. "He has state-of-the-art analytical equipment." Claeys will compare samples from Popigai and Alamo Breccia to determine if the impacts were caused by asteroids or comets.

Warme and his graduate students are still piecing together the record of what formed the Alamo Breccia those many million years ago.

They have studied about three eighths of a circular area, the middle of which could be near the precise site of the impact. Locating the center of the crater might prove difficult, however, because the site extends onto the secret military base known as Area 51. Extraterrestrial activity, it seems, may still be plaguing the area.

Mines Magazine, September/October 1999