How It Works - UK (2020-02)

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SCIENCE

Sediment cores retrieved by the JOIDESResolutionarerewritingthehistoryofplanetEarth

DISCOVERED BY THE JR

“Coresamplesare

helpingtoanswer

questionsabout

Earth’shistory”

corelab.Heretechnicianscleantheplastic

barrelsandcutthemdow ninto1.5-metrepieces.

Thesepiecesthensitinracksinsidethelabuntil

theyreachroomtemperature.Whenthey’re

readytheygothroughmachinesthatmeasure

theirdensit y,magnetismandacousticvelocit y–

thespeedsoundtravelsinsidethem.Thisgives

thescientistsa generalideaofwhat’sinside.

Nexttheteamsplitthecoreslengthways:half

ofthecorestayswholesothescientistshavea

recordofwhereallthepartscamefrom,andthe

otherhalfischoppedupforfurthertesting.The

teamneedtobequick;assoonasthesediments

areexposedtotheairtheystarttochange.

Rockexpertscalledsedimentologistslookat

theintacthalfofthecoreindetailanddescribe

ever y thingtheycansee.Thenstratigraphers

andmicropalaeontologistsgettoworkonthe

samples.Thesefossilscientistsspecialisein

ancientplankton,andthespeciestheyseeunder

theirmicroscopescantellthemhowoldthe

sedimentsare.

Chemistsalsolookatthesamples,probingfor

changestothecalciumcarbonatefromfossil

shellsandthecarbonfromliv ingthings.This

cantellthemwhathashappenedtothe

sedimentssincetheywerefirstdeposited.

Theyalsoperformsafet yteststostopthe

drillteamfromstrikingdangerousoilorgas

deposits.Theylookoutforchemicalscalled

hydrocarbons– a signthatthedrillmightbe

gettingclosetofossilfuels.

Backondeckwhenthecorecollectionhas

finished,theteamsendinstrumentsdow nthe

drillhole,a techniquecalled‘dow nholelogging’.

Sometimespiecesofthecorecangomissing.

Lookingbackintotheholehelpsthemtolinethe

fragmentsup,makingsurethattherecordisin

therightorder.

Whenanexpeditionendsthedatacollected,

andthecoresthemselves,becomeavailablefor

scientistsacrosstheworld.Keptsafeingiant

fridges,theseprecioussamplesarehelpingto

answerquestionsaboutEarth’shistor y,andto

predictitsfuture.

What’s in a core?

The sediment cores retrievedbythe

JOIDES Resolution contain stripesand

bands, a bit like the rings of atree.The

layers of rock are made fromparticles

that settled to the bottom of theocean

millions of years ago: clay, sandandsilt

washed from the land by riversandrains;

fossil shells and faecal pelletsbelonging

to ancient sea creatures; ashanddust

from volcanic eruptions; evenparticles

from space, deposited by asteroids.

Each layer records a point inthehistory

of our planet. Examining the sediments

can reveal the temperature ofthewater,

the sea level, the direction ofthe

currents, the movements of tectonic

plates and even the polarity ofEarth’s

magnetic field.

Sediments from the sea floor containthe

fossilised shells of microscopic plankton

©A

amy

DINOSAUR

DEATH RECORD

When the JR drilled into the crater left by the

dinosaur-killing asteroid, the sediments

revealed the aftermath of the impact. First

there’s a layer of glass, then a layer of ash,

then all the large plankton fossils disappear.

POLLUTION-

MUNCHING MICROBES

Sediments retrieved by the JR contain

billions of tiny fossils. JR scientists have also

found strange organisms living under the

sea floor, including microbes that eat oil and

bacteria that make electricity.

MAMMOTH-KILLING

MEGA FLOODS

At the end of the last ice age, melting

glaciers triggered waves of catastrophic

flooding. Sediments collected by the JR

contain the pollen and spores that washed

out to sea as water rushed over the land.

TREESBURIED

AT SEA

JR scientists drilling in the Bay of Bengal

found 19-million-year-old wood chips from

trees that grew high in the Himalayas. They

think melting glaciers tore the mountain

plants from the ground and buried them.

The JOIDES Resolution docks

in ports around the world

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