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mary caperton morton

Did the Medieval Warm Period welcome Vikings to Greenland?

Vikings are often depicted as hardy folk and fearsome warriors, but they were not immune to the harsh realities of the northern latitudes. Archaeological evidence suggests that Viking migrations around the North Atlantic were highly influenced by climate, with new settlements being colonized during warm periods and abruptly abandoned during colder times. However, according to a new study of glacial movements in Greenland during the time of Viking occupation, the local climate may have been just as cold when the Vikings arrived as when they left 400 years later. The finding may further shrink the area thought to have been affected by the Medieval Warm Period.

09 May 2016

Looking for life in coldest, driest Antarctica

Antarctica is nicknamed the “White Continent,” but one site — University Valley in the continent’s McMurdo Dry Valleys region — has remained virtually snow-free for more than 150,000 years, making it the coldest, driest desert on Earth. For the past four years, researchers involved in NASA’s ASTEP (Astrobiology Science and Technology for Exploring Planets) program searched for signs of life in the valley because it is thought to closely resemble the northern polar regions of Mars where the Phoenix spacecraft landed in 2008. In a new study, though, the team reports that it came up empty-handed, confirming that University Valley is indeed one of the least-habitable places on Earth.

05 May 2016

Fish evolved quickly after earthquake

Evolution is often thought of as occurring over very long timescales, but as a tiny Alaskan fish demonstrates, significant changes can take place in just a few generations.

03 May 2016

Growth rings in rocks reveal past climate

Paleoclimate studies often depend on mineral or sediment layers deposited seasonally or annually in caves, lakes and ice, but such records leave gaps where caves, lakes or ice sheets aren’t found. Now, scientists using a new technique that analyzes calcite layers ringing pebbles and rocks in arid landscapes are opening a new window onto the climate history of western North America. And because such deposits are found all over the world, the technique might prove to be a useful new tool for studying paleoclimate globally.

02 May 2016

Humans evolved early to be more efficient sleepers

We humans spend about a third of our lives asleep. While that might sound like a lot, we require less sleep than most mammals. In a new study, researchers have quantified how much less sleep we need than other primates, and the findings may offer clues to how and when human sleep patterns evolved.

22 Apr 2016

China's Red Deer Cave people may have survived until the last ice age

In the 1980s, a collection of bones from very small hominids was excavated from a cave in southwestern China, alongside a number of bones from a species of large red deer. Nicknamed the “Red Deer Cave people,” but not yet declared a distinct species, researchers previously dated radiocarbon in the sediments where the bones were found to about 14,000 years ago. In a new comparative study, the same team has now found that the hominids from which the bones came appear to have been similar to — although far smaller than — Homo habilis and Homo erectus, suggesting it could indeed be a new species.

19 Apr 2016

An absentee note for ancient blueschist: Lack of metamorphic rock does not date onset of plate tectonics

Plate tectonics is a defining characteristic of our 4.5-billion-year-old home planet, responsible for earthquakes, mountain building, and much of the evolution of the planet’s oceans and atmosphere. But when this formative process began is a mystery. Some researchers have pointed to the lack of blueschist — a type of metamorphic rock that only forms in tectonically driven subduction zones — in rocks older than 800 million years as a clue to when subduction began. But a new study rules this option out, offering a novel explanation for the rock’s absence in ancient rocks.

05 Apr 2016

Downgoing plate topography stopped 2005 Sumatra rupture

In late March 2005, a magnitude-8.7 earthquake struck off the northwest coast of Sumatra, Indonesia, rupturing a portion of the Sunda Megathrust Fault and further terrorizing a region still reeling from the devastating 2004 Boxing Day earthquake and tsunami just three months prior. The March quake, however, could have been far larger than it was, according to new research. Scientists have identified a topographic barrier on the oceanic Indo-Australian Plate — which descends under the Sunda Plate in the Sumatra Subduction Zone — that may have stopped the 2005 rupture from propagating farther.

04 Apr 2016

Inside an icthyosaur's brain

While the dinosaurs were busy ruling the continents in the Mesozoic, an order of marine reptiles known as the ichthyosaurs ruled the oceans. Ichthyosaurs are well known from numerous fossils, but they are often found flattened, limiting researchers’ ability to study the skulls and braincases as they existed in life.

01 Apr 2016

Human-induced quakes included in new seismic hazard maps

The U.S. Geological Survey (USGS) regularly releases National Seismic Hazard Maps that summarize hazards from potential ground shaking produced by faults around the country. This year, for the first time, those maps include not only natural earthquakes, but also earthquakes induced by human activities — particularly injection of wastewater produced during oil and gas extraction practices. The new maps were released Monday on the USGS website.

29 Mar 2016

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