Taxonomy term

sediment

Sinking sediment in deltas is as important as swelling seas

Sea-level rise due to melting ice is a common worry in coastal areas. But the sea-level story is much more complicated: What lies below the surface — sediment, and the rate at which it compacts — is also an important consideration, especially in deltas.

In a new study, researchers exploring the role of subsurface sediment compaction in coastal subsidence along Egypt’s Nile Delta, most of which lies just a meter above sea level, found subsidence rates there are four times greater than the rate of sea-level rise.

26 Sep 2013

Mississippi Delta drowning

The Mississippi River Delta is arguably the most geologically (and politically) dynamic delta in the United States. Subsidence, sedimentation, sea-level change and human manipulation constantly alter the landscape at the end of North America’s longest river. But now, researchers say, the beloved delta may be irrevocably shrinking.

24 Nov 2009

Re-examining the Burgess Shale

About 505 million years ago, the continent that would become North America straddled the equator. With no terrestrial plants or animals, the land was a barren landscape. The warm, shallow sea bordering the continent, however, hosted a carbonated reef teeming with a diverse array of organisms, most of which were relatively small bottom-dwellers. Periodically, the animals would get washed over the reef and deposited at its base, where their bodies accumulated in the muddy sediments. Today, these creatures are beautifully preserved in the Burgess Shale.

24 Aug 2009

Giant dunes, not mega-tsunami deposits?

About four years ago, a group of scientists proposed that a series of giant, wedge-shaped sandy deposits found along the shores of southern Madagascar might be evidence of a giant tsunami — a “mega-tsunami” — generated by an asteroid that may have blasted into the Indian Ocean sometime in the last 10,000 years. Furthermore, the scientists said, such impacts and the resulting tsunamis may have occurred fairly frequently during this period. To search for evidence of these impacts, the researchers formed the Holocene Impact Working Group.

05 Aug 2009

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