Featured Research

from universities, journals, and other organizations

Snail Fossils Suggest Semiarid Eastern Canary Islands Were Wetter 50,000 Years Ago

Date:
November 2, 2009
Source:
Southern Methodist University
Summary:
Isotopic measurements performed on fossil land snail shells found in ancient soils on the subtropical eastern Canary Islands resulted in oxygen isotope ratios that suggest the Spanish archipelago off the northwest coast of Africa has become progressively drier over the past 50,000 years, according to new research.

Fossil land snail shells from the Eastern Canary Islands.
Credit: Image courtesy of Southern Methodist University

Fossil land snail shells found in ancient soils on the subtropical eastern Canary Islands show that the Spanish archipelago off the northwest coast of Africa has become progressively drier over the past 50,000 years.

Isotopic measurements performed on fossil land snail shells resulted in oxygen isotope ratios that suggest the relative humidity on the islands was higher 50,000 years ago, then experienced a long-term decrease to the time of maximum global cooling and glaciation about 15,000 to 20,000 years ago, according to new research by Yurena Yanes, a post-doctoral researcher, and Crayton J. Yapp, a geochemistry professor, both in the Roy M. Huffington Department of Earth Sciences at Southern Methodist University in Dallas, Texas.

With subsequent post-glacial climatic fluctuations, relative humidity seems to have oscillated somewhat, but finally decreased even further to modern values.

Consequently the eastern Canary Islands experienced an overall increase in dryness during the last 50,000 years, eventually yielding the current semiarid conditions. Today the low-altitude eastern islands are characterized by low annual rainfall and a landscape of short grasses and shrubs, Yanes says.

The research advances understanding of the global paleoclimate during an important time in human evolution, when the transition from gathering and hunting to agriculture first occurred in the fertile Middle East and subsequently spread to Asia, North Africa and Europe.

"In the Canary Archipelago, land snails are one of the rare 'continuous' records of paleoclimatic conditions over the last 50,000 years," Yanes says. "The results of this study are of great relevance to biologists and paleontologists investigating the evolution of plants and animals linked to climatic fluctuation in the islands."

The researchers' isotopic evidence reflects changing atmospheric and oceanic circulation associated with the waxing, waning and subsequent disappearance over the past 50,000 years of vast ice sheets at mid- to high latitudes on the continents of the Northern Hemisphere.

The research also is consistent with the observed decline in diversity of the highly moisture-sensitive land snails.

Land snail shells are abundant and sensitive to environmental change and as fossils they are well-preserved. Measurement of variations in oxygen isotope ratios of fossil shells can yield information about changes in ancient climatic conditions.

The shells are composed of the elements calcium, oxygen and carbon, which are combined to form a mineral known as aragonite. Oxygen atoms in aragonite are not all exactly alike. A small proportion of those atoms is slightly heavier than the majority, and these heavier and lighter forms of oxygen are called isotopes of oxygen.

Small changes in the ratio of heavy to light isotopes can be measured with a high degree of accuracy and precision. Variations in these ratios are related to climatic variables, including relative humidity, temperature and the oxygen isotope ratios of rainwater and water vapor in the environments in which land snails live.


Story Source:

The above story is based on materials provided by Southern Methodist University. Note: Materials may be edited for content and length.


Cite This Page:

Southern Methodist University. "Snail Fossils Suggest Semiarid Eastern Canary Islands Were Wetter 50,000 Years Ago." ScienceDaily. ScienceDaily, 2 November 2009. <www.sciencedaily.com/releases/2009/10/091027170853.htm>.
Southern Methodist University. (2009, November 2). Snail Fossils Suggest Semiarid Eastern Canary Islands Were Wetter 50,000 Years Ago. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2009/10/091027170853.htm
Southern Methodist University. "Snail Fossils Suggest Semiarid Eastern Canary Islands Were Wetter 50,000 Years Ago." ScienceDaily. www.sciencedaily.com/releases/2009/10/091027170853.htm (accessed September 23, 2014).

Share This



More Fossils & Ruins News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Iconic 'Easy Rider' Chopper Bike to Go on Auction Block

Iconic 'Easy Rider' Chopper Bike to Go on Auction Block

AFP (Sep. 19, 2014) The iconic Harley-Davidson motorbike ridden by Peter Fonda in the 1969 classic "Easy Rider" is to go under the hammer in California, and auctioneers predict it will make at least $1 million. Duration: 01:09 Video provided by AFP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Egypt Denies Claims Oldest Pyramid Damaged in Restoration

Egypt Denies Claims Oldest Pyramid Damaged in Restoration

AFP (Sep. 17, 2014) Egypt's antiquities minister denied Tuesday claims that the Djoser pyramid, the country's first, had been damaged during restoration work by a company accused of being unqualified to do such work. Duration: 00:56 Video provided by AFP
Powered by NewsLook.com
King Richard III's Painful Cause Of Death Revealed

King Richard III's Painful Cause Of Death Revealed

Newsy (Sep. 17, 2014) King Richard III died in the Battle of Bosworth in 1485, and now researchers examining his skull think they know how. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins