时间:2019-02-23 作者:英语课 分类:英语时差8,16


英语课

By calculating how old the rocks are where we find these ancient compasses, we can figure out how long ago the magnetized parts were locked in. That tells us which direction was magnetic north tens of thousands of years ago. Surprisingly, it’s not always the same as north is now. Occasionally the poles change places. So, did the north pole drift slowly southward, so that at some point magnetic north was in, say Mexico city? No. The rocks tell us that, during pole reversals, there is a several thousand year period during which the earth’s magnetic field is either gone or very much weakened. At these times north and south become arbitrary terms. Eventually the magnetic field re-establishes itself, and it seems to be a matter of chance which side comes out north and which south.



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a streaker
a.m.
adenanthrea microsperma l.
AGA,A.G.A.
air cleaner
annual ring density
Bayerbach bei Ergoldsbach
Bence-Jones protein
blacklers
cagewashes
cartographic design
cerebral irritation
chief executives
ciprofibrate
clutter rejection
coherent brittle stage
commutator-controlled weld
cryogenic technology
digital to image conversion
discipleships
double faced hammer
dress
drewe
Dunnet
eeps
efficiency factor
enthalpy of swelling
equatorial system
exterior varnish
exult over
farigue
Fat Analysis Committee colour
flat billet
get his
Gojra
graynet
Guaranteed Death Benefit
half-binding
hexaquarks
high-sulphur fuel
improvement by lessee
injector feed
interaction volume
intoxilyzer
IP fragmentation IP
key variable
korahl
leakage spectrum
lenslets
linolenate
logolepsy
long - term care
loop termination
lql
lutnick
malgwyn
material for test
Medveditskiy
Metroval
mintels
miscellaneous asbestos product
Neolitsea pinninervis
newbattles
non-dividend payee
operational technical manual
penetration of grease
pole setting
pretell
primary mother-tree selection
production strategies
psauoscopy
Qarshi
random noise level
reference oscillator muting
reservoir sensitivity evaluation
reversible code
roller-ball
runners
salty milk
scarifie
see sth with half an eye
sentenceable
shilt
Shimabara-hantō
simple radical
special transfer paper
steinhausers
sulphur cement mortar anchor
superefficiency
temperature classification
thelephoid
theory of growth
thermal processes
thrash over
tooth abscess
USB stick
velascas
vermilions
voltaic irritability
wad hamid
with expedition
zygoplast