The Eternal Frontier: An Ecological History of North America and Its Peoples (review)

The Eternal Frontier: An Ecological History of North America and Its Peoples. By Tim Flannery. New York: Atlantic Monthly Press, 2001. Pp. 404. $27.50.

Tim Flannery is the Director of the South Australian Museum and a professor at the University of Adelaide. While a visiting professor at Harvard University, he dived into the wealth of North American fossils to read their story. For his efforts, we are all richer. Flannery's book The Eternal Frontier, covering the ecological history of North America, is one you will not forget: it is extremely well-written and covers an enormous temporal scale with detail, style, and intellectual rigor. Flannery's prose leads us through time on a most enjoyable journey. He sparks the imagination to conjure images of changing flora and fauna in North America, while globally, continents rip apart and collide. Nearly half the book entails the history of people entering North America in various waves over the last 13,000 years.

When the narrative arrives at the present, a point where most history books end, Flannery takes the lessons of the past and predicts future directions for nature on this continent--something we residents fail to do in a serious manner. Our blindness has already ravaged much of the continent's grandeur. At what ecological cost can we maintain an economy described as a "perpetual cornucopia machine"? Is the wealth of the land really eternal, or is it now only a figment of our ingrained frontier mentality?

Flannery's extraordinary history of North America begins when the continent was divided, north to south, by an inland sea. As this sea shrank in size, the land increasingly was covered with flowering trees, including relatives of the magnolia. This evergreen blanket extended to Alaska, while at the same time Mexico was submerged under warm, azure waters that teemed with marine life. It was the late Cretaceous, about 65 million years ago.

Meanwhile, low on the southern horizon, an asteroid 10 kilometers in diameter approached our planet on a collision course at 90,000 kilometers an hour. The intensity of the impact is almost beyond comprehension: it left a crater 180 km across and 5 km deep. Because the meteor struck at a low angle, it generated more heat than if it had been a vertical strike, exceeding the solar energy we receive by three orders of magnitude. Because the atmosphere held 10 percent more oxygen than it does today, the event was predictably flammable. Flannery likens the impact to a giant divot from a chip shot, raining molten rock and debris directly on North America--from the point of impact to 7,000 kilometers north. As the giant crater filled its cavernous depth with water, the seas retreated from their shorelines. Then, the waters returned in a tsunami, perhaps as high as one kilometer. Krakatoa, which released energy equal to 10,000 atomic bombs, was a micro-event by comparison.

There were global impacts, and indeed the iridium layer circled the planet. Dinosaurs, which had ruled the globe for roughly 160 million years, vanished, along with many other species. From the cinders came a new North America, which because of the direction of meteor had received the brunt of the blow. Life here was confined to scattered fern spores. Moving to the north, 80 percent of the species were lost in what is now North Dakota, and that pattern extended to the Arctic Circle. On the other hand, to the south of the crater, there was no tsunami, no huge shock wave, and perhaps no fires. Some of the species that vanished in the north thus survived in the south.

At that time, North and South America were separated by water. So, early recolonization by immigration had limited opportunities. The rebirth of North America may have been driven by indigenous plants, perhaps sheltered from the impact...