Earth articles from April 1997

Earth archives from April 1997

Tuning in to tornadoes. (sound wave prediction)
April 1, 1997... Tornadoes twirl across the land in a dance of destruction, and researchers are learning that it's a noisy step that shakes the ground. By tuning in to sound and seismic waves, scientists hope to detect the deadly funnels before they appear...

EarthChronicles. (significant geological events in the November 13, 1996 to January 14, 1997 period)
April 1, 1997... This dateline covers the period from November 13, 1996, to January 14, 1997. It includes all reported earthquakes of magnitude 6.4 and higher. November 14 -- Torrential rains cause a landslide in the Makaha Valley on the island of Oahu,...

Jurassic ants: a 160 million-year-old ant nest.
April 1, 1997... A picnic in the park, even Jurassic Park, wouldn't be complete without ants. The oldest known fossil of an ant dates to the middle of the Cretaceous period, 90 million years ago. But a surprising new, fossil suggests that ants have been...

New angle on a killer? (dinosaur extinction caused by asteroid impact)
April 1, 1997... Finding a killer 65 million years after the crime was committed is no easy task. But when it comes to the culprit behind the death of the dinosaurs, paleontologists have assembled some remarkably specific circumstantial evidence. Most think...

Living proof. (stromatolites)
April 1, 1997... "Here's the situation," John Grotzinger explains. "If you take a rock and you don't see fossils in it, how do you know that it ever had anything to do with life? It's as simple as that." Grotzinger, a geologist at the Massachusetts Institute...

Life on the brink. (extinction of species)
April 1, 1997... The bizarre beak -- a short lower bill topped by a long, sabrelike upper bill -- poked up at Helen James from a collection of bird bones held out to her by a Hawaiian man. James, a paleontologist, realized she was looking at the beak of a...

Voyage to the bottom of the lakes. (bathymetric maps of Great Lakes)
April 1, 1997... The Detroit River begins where Lake St. Clair ends, where eastern Michigan and western Ontario pinch the lake into the shape of a tilting heart. From the bottom of that heart, the river squeezes south past Detroit and into Lake Erie. But...

Earth in action: portraits of the planet.
April 1, 1997... The high peaks of the Rockies that soar above my home in Boulder, Colorado, cut the same jagged outline against the sky day after day. These mountains seem monumental -- and eternal in their majesty. Yet in geological time, they are as...

Loihi rumbles to life. (Hawaiian undersea volcano)
April 1, 1997... Somewhere beneath the waters southeast of Hawaii, the ground was shaking. In mid-July 1996, seismometers at the Hawaii Volcano Observatory began to register a furious series of tremors from the region. Fred Duennebier, a seismologist from...

Bridge to the past. (Asia-America land bridge)(includes related article on fossilized bison)
April 1, 1997... Did the first people to arrive in the New World have to get their feet wet, or could they have crossed on dry land? Did they come by boat or on foot? Such are the questions facing researchers studying the history of the peopling of...

Crystal clear. (crystal formation)
April 1, 1997... The brilliance of the ancient Greeks still illuminates our politics, philosophy and science, but even they didn't always get it right. Take, for instance, the name they applied -- or misapplied -- to the common mineral quartz. Greeks...

Ice Age journey. (Alaska's Harding Icefield)
April 1, 1997... A steady 20-knot wind has been blowing out of the west for several hours. It comes up off the water and travels over some 20 miles of solid blue ice and cold white snow. By the time it reaches us, it is frigid enough to blow out our lives...