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Climate Change


Dry summer reveals ancient remnants; an aquatic meal for ruminants

by Alexandra A. Taylor
August 18, 2018 | A version of this story appeared in Volume 96, Issue 33


A monumental find

An aerial photograph of a field of dried wheat with the imprint of a henge visible.
Credit: Anthony Murphy/Mythical Ireland
A well-cropped photo: The drone’s aerial view plus the right ground conditions finally revealed this henge.

Anthony Murphy made the discovery of a lifetime when his hovering drone spied a potentially 4,500-year-old circular monument, or henge, sitting in a wheat field in Ireland’s Boyne Valley.

Murphy has been documenting the valley for 19 years and has authored a book on local history and lore called “Mythical Ireland: New Light on the Ancient Past.” But it wasn’t until a severe drought this summer turned the Emerald Isle beige that the henge’s footprint, located minutes from his home, became visible from the air. The discovery was a surprise; thanks to prior knowledge of archaeology and the landscape, “I knew fairly quickly that what I was looking at was likely to be a henge,” Murphy tells Newscripts. “I was very excited from the moment I saw it.”

The footprint consists of a series of double dashes in a circle broken at regular intervals. The dashes are surrounded by two rings of dots, which likely held posts. This henge was made from different materials than Stonehenge, the Neolithic ring of standing stones in Wiltshire, England. “There’s no immediate sign that there were any stones involved, but rather some sort of very large wooden structure,” Murphy says. On one side of the circle sits a large rectangle, which he suggests may have been an entrance feature. The entire structure is 150 to 200 meters in diameter and may once have accommodated thousands of people.

Over time, the wood from the structure would have rotted away, but the footprint remains visible because of differences in the soil makeup, Murphy theorizes. The archaeological features are likely located less than a meter beneath the soil surface, but the true depth will be known only if an excavation takes place. The site is located on private farmland, though, which makes any dig unlikely in the short term. Other, less disruptive strategies are possible, such as thermal imaging and further aerial surveying.

Conditions had to be just right for the footprint to be visible. If the field had been plowed or sprouted grass instead of wheat, “you wouldn’t be able to see this henge at all,” Murphy says. “And of course, that’s the reason it has remained invisible up until this point.”


Chewing over a change in diet

A photo of a cow chewing on red seaweed.
Credit: C&EN/Shutterstock
Surf and turf: A seaweed-spiked diet cut bovine methane emissions by 58%.

Though the Irish drought and associated heat wave may have revealed a long-lost henge, researchers in California are looking for ways to slow the planet’s warming.

Cows and other grass-munching livestock are notorious polluters. Fiber and starch ferments in their stomachs during digestion, causing the cattle to belch and otherwise emit the greenhouse gas methane. Ermias Kebreab at the University of California, Davis, has been supplementing cows’ diets with seaweed to see if it will tone down the large amount of the gas they produce—a timely endeavor, seeing as the State of California has passed legislation to cut emissions of this and other pollutants to 40% of 2013 levels by 2030.


Enter Asparagopsis armata, a marine red algae species that contains compounds that inhibit methane production. Kebreab’s team feeds the seaweed to dairy cows by grinding it and mixing it with molasses and hay. The cows are trained to make use of a Breathalyzer-like instrument that measures their postprandial output. Kebreab’s preliminary results show that the cows on the seaweed diet exhale less than half the methane of their control-group counterparts.

The seaweed supplement could be a promising way to reduce agriculturally produced methane—that is, if the conclusions are borne out by further animal testing and if the seaweed can be grown and distributed in a way that doesn’t significantly contribute to greenhouse gas emissions. Unfortunately, though the seaweed feed could mean the cows’ burps are less polluting, it won’t make them any more polite.

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