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.lottrttttl o.f Puleolitnttologt
O 1998
Kltlrcr At ttdenttr 20:
-109-.122.
1998.
fttrltli.slrer.s.
Pritted in tlte NeÍlte
rltrrttl.s. 409
The end
of moai quarrying and its effect
on Lake Rano
Raraku, Easter
Island
Henri
J. Dumontr,
Christine
Cocquytr. Michel
Fontugner.
Maurice Arnoldz,
Jean-Louis
Reyss2,
Jan Bloemendal3,
Frank
Oldfield3,
Cees L. M. Steenbergen-+,
Henk
J.
Korthalsr
& Barbara
A. Zeebs
I In,stitttte
rf'Anintttl Ec'ologr,
(Jrtiver^Eitt'of'GenÍ,9000
(ient, Bel,qiLurt
(e-ntrtil:
Henri Dtuttont@RUG.AC.BE)
) CenÍre tles Fcribles
Rudiottctivités, Luborutoire Mi.rÍe CNRS-CEA,
GiÍ'-.sLtt'-Yt,ette, Frurtct
3 Deprtrtmení rlf Geogrctphr, [Jniversitt' of'
Liverltool, U K
1 NEI,
Centre.for
Linrnologr;
-lóJ t AC Niettv'er.slui.s,
The Netherlttnrl.s
5 Qtteen's IJrtiver.;itt',
Deprtr'Íment
of'Birilogt', PEARL Lul:xtrutor'1',
King.;tou, Otttrtt'io K7L -JNó,
Cttruttltt
Rcccivecl
3
April
lc)9-5:
acceptcd I .lanuarv
1998
Kev worcl,i.'
Lake cores. Easter Island culture, South Americii. diatorns. cladocerans.
ostracocls.
chrysophytes.
magnetic
properties.
palaeopigments
Abstract
We
reconstruct
aspects
of the
history
of Easter
Island
over
the last
zl-5
centuries
based on
the stucly of a cgre
from Rano Raraku Lake" sitr-rated in the crater that cclntains
the quarry of the islancl's giant statues
ctr motti. We
use microfbssils of plants and animals to identify five zones.
The last three of these
are separatecl
by r,vaves
clf
imrnigration
from South America and Írom the subantarctic.
We arsue that the first
or South American wave.
clatecl
to the second half of the l4th century, may represent
a visit by South American Indians. Magnetic infbrmation.
pollen, diatoms. chrysophyte stomatocysts
and fossil plant pigrnents reveal a synchronisnt between the Sg1rth
Anrerican
contact
and the cessation
of nutcti
quarrying. We thereÍore
suggest that Amerindians contributed
to the
cr.rltural
collapse
of the island.
The second
or subantarctic
wave may reflect an early European visit to the island.
possibly
by Cpt. James
Cook tn 1114.
or by Jacob Roggeveenin 1722.
Introduction
Rapa
Nui, or Easter
Island.
aÍier the Dutch name
'Paascheiland'
given
to it by its first
European
visitor.
Jacob
Roggeveen
in I 722 is
a small
(area
c. |
60
krnr
).
grassy,
hilly
(max.
alt.
5l l rn
a.s.l.). subrropical
(21
"
07' S. 109
' 22' W), windy
and rather
rainy
(aver-
age rainfall
c. 1200
rnm
a l,)
volcanic
islancl,
situatecl
on the East
Pacific
rise. The nearest
land. whether
continents
or other islands.
is alrnost
3 000 krn
away,
makin-q
Rapa NLri
the most
isolated
inhabitecl place
in
the world.
The
isliind
is f'arnous
fbr the
cultural
achievements
oÍ'its
inhabitants.
i.e.
the
giant
human
statues,
or moui.
that were
originally placed
on ceremonial platÍbrms,
the
uhu. The island
also
abounds
in petroglyphs.
and
possesses
a script,
the
rortgorongo,
that has remained
partially
undeciphered
to
date
(Bahn.
19961.
Two recent
books depict f'ascinating.
though
con-
flictin-e,
in-rages
of the cultr,rral history
of the islancl
(Heyerdahl.
1989;
Bahn
& Flenlcy.
1992).
Since
the
work
of Smith
(
l
96 I
a. b). there has
been
general
agree-
ment
that
the island's
cultural history
can be
divided
into
three
phases:
eurly
(from
-5tr'
century colonization
to c. ll00 AD), rniddle
(c.
ll00 to
c. 1680
AD).
and
late
(c. 1680
AD to the
present).
Thc last
phase
ush-
ered in an
era of decaclence
and
collapse.
the result
of
overpopulation
and
over-exploitation
of resourccs.
At the heart
of the conÍlict
between Heyerdahl
and
most
contemporary
archaeologists
and
ethnologists
is
the
question
of the origin
of the island people.
Heyer-
dahl
(
1952.
19U0. 1989)
Í.rrgues
for
a
rnultiple
invasion
rrodel.
in which Amerindians
came Ílrst.
Polynesians
.t
l0
later.
MainstreaÍn ethnology fhvors a single coklniza-
tion by Polyncsians.
Easter Island is noted Íor its low biological
diver-
sity. a conseqLlence of its isolation and small size.
Skottsberg's
(19-56)
fhmous dictLrm that the island's
fltlra of only :16
species
consists of 'waifs and strays'
is illustrativc. cvcn if some taxa. including the extinct
Jttlrueu
palrn
(Dransfield
et al.. l98rl), and the Írtrotrtiro
tree
were endernic.
Likewise. the terrestrial
i,ertebrate
and invertebrate fauna of the island is depar-rperate
(Carnpos
& Pena. 1973). and has neither endenrics
nor South Arnerican elernents. In cclntrast.
nunrerous
introductions
by hurnans
continuc to occur (Kuschel.
1963: Dunront
& Verschuren. l99l :
Desender
& Baert.
1996). There is
also
evidence fbr cxtinctions
Íclllowing
rnan s arrival on the island.
of flightless birds
(Stead-
rnan. 1995)
and of land rnolluscs
(Kirch et al.. in
preparation). The island has three permanent
fresh-
water lakes. situated
in the crilters Rancl Raraku and
Rano Aroi. and in thc caldera of Rano Kau. In addi-
tion.
numcrous srnall springs
and stagnant
pools
occur
across thc
island
(Figure
|
).
Until recently. thcir aqLratic
biota had not been str-rdied. The 1990 Gent Universi-
ty Expedition to E,aster Island
published
on diatoms
(Cocquyt. l99l). rotif-ers
(Segers
& DumonI. 1992).
and rnicrocrustaceans
(Dumont
& Martens. 1996). All
these
inventories
are extremely
species-poor. Dumont
& Verschuren
(
199 |
) note the absence of cnidarians,
molluscs. hirudineans.
and aquatic
hernipterans
and
coleopterans.
The Rano Raraku
crater
is asymmetric and of com-
plex geological
origin: it is Íamous as the source of
the
rtroui sculpturcs
(Bakcr. 196l: Baker & Buckley.
l()14).lts south
and south-east rims Íbrm a
clifïof tuÍf
fronr which Íhe nroul were carved
(FigLrre
2). Both the
inner
and outer
walls werc quarried.
In view oÍ-thc diÍ-
ficLrlty
of moving the
giant
statues
to their destination.
one of thc clcments of the
mysterious
questions
about
Easter Island. u,hich may havc involvcd (palrn)
tree
trunks
as
levers
or supports
(MLrlloy.
1910). and even-
tually led to the complete delorcstation of the island.
is why the inner wall was cprarried
at all. Yet, inten-
sivc curvins. involving only stone hand-axes
(rnetal
was unknr)wn
on the island)
occurred. In addition to
prodLrcing
statLles. quarrying gcnerrted
a lar-ec
amount
ol'erosivc rnaterial. This rubble later buried numer-
ous leÍi-behind nrouito the neck and spectacular
pic-
turcs
of re-excilvilted giants
can be secn in Heyerdahl
(
1989).
MLrch dcbris must have
been
washed into the
lake
(Flenley
et al.. l99l ).
An aerial
photograph.
taken
in Ar-rgurst 1990
(Figurc
2). shows
that the
slope
oppo-
site
the
qLlarry
is srnoother and
wider
than clsewhere.
and the
straight
lakc margin here suggests a filling-in
by
quarry
debris.
Palaeolirlnological
research on Rano RarakLr and
the othcr two lakes
was. to clate.
largcly lirlited to
palynology. The first sediment
cores.
raisecl
by the
1955 Norwegian expcdition.
revealed that the
island
was fornrerly Íorested
{Selling,
1961.
in Heyerclahl
&
Fcrdon. 196 |
).
Latcr
palynological stLrdics in
all three
lakes
(Flenley
& King. l9U4: Flenley et al." 1991)
revealcd
details
oÍ'the
island's vegetation
history.
Oth-
er
palacolirnnologicalvariables were
given less
consid-
eration
in these
papcrs,
and thc
validity of rnost
pr"rb-
lished racliocarbon
dates
was
qucstioned
(Karntninga
& Cotterell.
19U4).
Thc
present
investigation expancls
previous wurk. r"rsing
complcrnentary
techniqr-res.
Materials and methods
ln AugLrst
1990. we cored Rano
Raraku Lake
(surfhce
area.
inclnding
rnarginal
swarnp
c. t ha. maxintunt
depth c. 3 m. depth at coring
site c. 2 nt) from a
raft cornposed
of two Zodiacs.
upon
which it work-
ing
platforrn with a coring tripod
was ntounted.
Cores
were
taken
with a piston
corer that
possesses
a :l tn
plastic
core
barrel
of 5 cm diameter.
The corer
wíls
hammered
into the sediment
in
one continurtus
operul-
tion.
winched up. and
sectioned into I m len-uths fbr
subsequent
transportation by air.
Two
cores
were taken. one
in the
sor-rth-west.
one
in
the north-east
part
of the lake.
The
SW core
is located
ncar
the rniddle o1' thc 'transect'
of for-rr
cores takcn
by Flenley ct al.
(1991).
Here.
we rcport results frotn
the SW core.
Thc top
8-5 cr-n of sediment
consisted
of
a scrni-liqr-rid
peat.
rich in lcaf fragrnents of Scltoetto-
plectu,s
culiÍltnticu.E
(tolrtru).
a br"tlrush, ancl
Rtlt'gotr-
ttrtt rtcttrttirtuÍurtt
(ttn'uri).
a knotweed.
At the time oÍ'
sectioning.
there
was
evidence of considerablc
rnixing
within this
section. and thereÍclre
it was not
analyzed.
In the
laboratory. the sections
were first
analyzed
non-destrr"rctively
(with
the core still
in
the
plastic pipe)
fbr mineral rnagnetic
properties. The Íollowing vari-
ables were
measurcd:
1,,,-,,,.
the magnetic
sLrsceptibili-
ty. using a
Bartington
Instruments meter:
\. the anhys-
teretic
remanence.
irnparted
ursing
a 100
rnT
(T
=
tesla)
alternating
field and a steady
fleld of 32 Airn, and
SIRM. the
saturation
isothermal rcmanence. imparted
in
a I T pr-rlsed field.
1
. \ ",,'
and SIRM are
proportional
mainly to the concentration
of Íerrimagnetic
rninerals.
such
as
rlagnetite. HIRM, hard
IRM, is the
isother-
Áll
+l I
:
?.
E
a
.=
t
a
.=
')
J
i
=
2
a
=
-
=
=
a)
a
a
=
=
-
=
=
=
--
-
=
I
a
'l
Ea
a)
;
t'!
I .v'
,r lt
-u
.U
-.
.' =
--.
.E
é=
i--
a'a=
,i'
i.a
- iÍ
!;
c-tr
>:3
a
\'>
!^,
;\ --
I--_--r
ll
le I
|
; :, i
Itr ll
tF ilI
t(/)ltlt
l< ll I
I t o, l
| '{!
I
I
t
I
-J
t
i
:
i
i
ll
it
I
it
I
ll
ll
I
i
i
i
I
1
I
li
1
ii
ii
il
lr
Il,
rÍ I
li
l,
t
I
1i
il
ll
lr
I
iÍ
l,
lí
I
li
ir
li
l,
ll
t,
ll
I
li
I'
I l_ _
ll')
-lL
wffi,#'1
,S
-\"
ï
ffi
tl,&j,:
l',1' :l; i ii:il,
I
' ':ff:
+ír
"-'i:
{i.i: '',
rÍÈ|:
r.$.:i:
ds:t
::t{i
;*dili i
ffiiirl
s{:
I"igrrrt, l. Aerial photouraplr
ill'Rano Raraku showing thc lakc on thc Íloor oÍ'thc cralcr'.
cofing site is inclicatc-cl hy"u \\'hite
circlc. Thc clitl'Í.nrn which thc lrorrl wcrc clfvccl is to
thc clií'l'.
insiclc thc crater.
Fronl this cliÍl-. a gcntle slopc
of clebris.
gcncfatccl
bv centuries
stlaight lakc nrargin opposite thc quarrr'. sr-rsscstivc oÍ'infilling bv quallv clcbris.
ll'ith Ír-inuing belt ancl Íloating islands ol'lr.,torrr. Thc
the leli. Sclr.r.rc rirr.rrl arc visible as dots at thc firot o1'
ot'quarrving. sradcs
to thc lakc. Arrou's dcliurit thc
rnal remanence
acquired
between 0.3 and I T. ancl
is
proportional
to the concentration
clf
irnperfèct
antifèr-
roma-gnetic minerals sLlch
as haernatite and
goethite
(Oldfield
et
al..
1985). All remanences were
measLlred
on a MOLSPIN flr.rxgate
spinner magnetometer. The
intervariate ratios
\,,rn,/\
and
\,,,.,,,/SIRM
reflect varia-
tions in
the
fèrrimagnetic
-9rain-size,
with
higher
valLrcs
indicating
finer
grains.
The IRM reverse valLles were
obtained by irlparting
a SIRM and then exposing
saln-
ples
to reversecl
pulsed
field strengths
of 20.
,10.
100
and
300
mT. Relative
changes in IRM reverse
values
Ítrr fields
of 20
and
40
mT mainly reÍlect
ditfèrences
in
the
grain-size
of the
fèrrimagnetic
fraction. The values
tor a 300 rnT reverse Íield reÍlect
the fèrrintiignetic:
i mperfèct
anti Íèrri magnetic riiti
o.
Next.
the core
sections were
opened and sampled
Íor anirnal and
plant
rnicrofbssils. fbssil plant pig-
Ínents,
and dating
by 'tC and
ll0Pb.
Except fbr clat-
ing,
samples
were
taken at
zl
or 5 crn
inter"vals
between
0.U-5
and 1.70 rn.
ancl at increasingly wider intervals
deeper
in the core. Son-re weighecl
snb-samples were
subjected
to alkali
(10%
KOH)
treatment for the
prepa-
ration
of cladoceran remains
and ostracod
valves.
and
tcl
stanclard acid treatment firr pollen.
spon-se
skeletal
elements.
diatom fr'ustules.
and chrysophyte stomato-
cysts.
Frfïeen samples
(see
Table 2) were
preserved
Ltnder a nitrogen atmosphere and subjected to fossil
plant pigment
analysis.
They were extracted in ace-
tone. separated by straight-phase high-perfbrmance
liquid chromatography. and
identified and
quantified
according
to Korthals & Steenber-uen
(1985).
Next.
macrofossils of Íotoru and of tuvori were assessed
on a presence/absence
basis by sieving the
sediments
through a 2 rnm sieve.
One large stem fragment of
Polt'gortunl
(at 130-13-5 cm)
wils recovcred
and
llC-
dated
by ./-counting. Two bulk sarnples.
at 170
cm
and at
220 cm were AMS-rrc dated.
Ei-sht samples.
at -5 crn intervals. between 100 and l3-5
crn. were
analysecl
1ot'
rtop6. ïrtal ll0Pb activity
was mea-
surecl by alpha-spectroscopy. through
ll{)p,r.
Thesc
mcasLrrements
were
checked by measuring
rl0Pb
and
116B',
directly by
garnma-spectroscopy, to
confirrn that
none
of the
total
rl{)p6
was Llnsupported. at the
low-
back-uround underground
laboratory of Modane,
at a
depth of
2km
below the
Alps. For details of the method,
see Reyss
et
al.
(
199-5).
tu
413
7, ./ '=
a) .,'-
/.r.4
?J)
ra2
!':
-Y;
'')-
.i>J
í-.-
': - .\
oí á!
=.a:
tl -- -,
= ,,
'-
-=:
'-!
^^È
.=.a
í'ó
>1:. =
:a 7 --
7.x l'r
-L;:
- ) -.=
=',
-!^
aj.-'=
^---
=.J=i
:!?t,v
---ítL
=-x>,
4'Vn;
..:
_- J>
/.?;a
'--
;-
tt7=
-..2-'
= :-+ -
:>x!
i ná c
- -, ;t -
71T..
:t-;;,7 \
: '- - Ír
j:-í F-
t^--'.
I i órc
-.*ó-
3i.-ï1
'- : -
=-: -:c
r4-^a
!i
-./.Va
.-J-a
1=:1 a'
-
5=ó':.
.27=
4.-'
'::=tf.
;- a ,-,, -
: .-' 'J - -:l-
\ L- -
RRRES
1
ctl
Ë'aoo
xr,-,
lJ-.|
-.
<>
l\r lrl
=.
o
l\t
êl
LJ.J
-.
o
t\l
cÍt
lr I
=,
o
ÈI
<F
lrl
-.
o
,\l
U)
o
F
QU;
LU<
o2
z. au
oh
àË
Za
ul H
-' ió
fió-É
ïe zo
t
b3
TIÀHÀ
OOOÍD
Es Q:
9- [m
Fg
sH
c
.u)
8 [o
? à6
cc..cDo
F^(I
CD\ <
o 9a
<
4
I,U Y
()O
c)<t!
azz
Íqm
ó43
o
tr,
Ë zoo
x
UJ
co
l1Z
- tr.l
>+
IJ
ïo
íL(L
Itl
N.
o
I zoo
:È
8R
cvN
ooo
Í(oco
(O
.(r
^v'rJ ^tlts
3lilv9uorí
oslvNrhrvl l't'lvco'l
1000
soo
)o?$gRPaag1e9aa'rrr
PT=FÈFNXHEER?E
lr!(\Nc\Jí)c,)è() tl t tt t
03'ldwvs s'l:l^3'l
414
Results
The core stratigriiphy is sirlple: below
2210
cm. the
sedirnent is an
inclr-uanic
silty
clay.
lclcally larninated.
that
gradually
changes into
an unlaminated
silty
clay
abclve
220
cm.
The
upper zone
consists
of an organic
silt with numerous
plant
fr-agments Íiom 135
cni to
the
top. The transition between thesc two zones is
sharp.
and takes
place
over a distance of less than
5 cn-r
(Fi-ur.rre
3).
Because
of the availablility of a detailed
pollen
study by
Flenley
et al.
(1991).
we recorded
pollen
by
broad categories
(palrnae
and non-palrnae) fbr striiti-
graphic
correlation with Flenley's study. Palrn pollen
declined
strongly frorn
220 cm Llpwards,
to become
insignificant
at 120
crn. Only a fèw
samples
contained
several
grains
above that level. This
profile
comparcs
perl'cctly
wrth
the record
of Flenley
et
al.
(1991).
Our
category
'others'
was
dominated by grasses
and rud-
erals. and
shows
the sarne spcctacular increase
above
130
cm:rs in Flenley
et al. (loc.
cit.).
We
did not
atteÍnpt to sepiirate Poltgoruln.
and
did not diflèrenti-
ate CyperÍiceae frorn
grasses.
The sr.rbfbssil
content
of the core showed a low
species richness,
in keeping with the poverty
of the
island's
present
biota.
There
were 38 diatorn species
(ourt
of c. 70 extant species.
the latter including
brackish-water fbrrns). one sponge
(not known in
extant
forrn Ír'om
the island).
one chydorid cladoceran
(identical
to the one
extant
species
on the
island).
ancl
one ostracod
(oLrt
of the three
extant
species
).
Chrysophyte storxiltocyst morphotypes"
analysed
by constrained incremental surn
of sqLlares
(CONISS)
cluster analysis
perfbrmed
using TILIA (Grimm.
1992), revealed
fbur distinct assemblage
zones
(Fig-
ure ,1).
Zone I extends frclrrr
the base of the core tcr
250
cnr and contained not
only the highest abundancc.
but also the
greatest
diversity of stoniatocysts
(Zeeb
&
Sn'rol. in
prep.).
This
zone is characterized
by a
group
of srnall. highly
ornamented cysts which have
previ-
ously been associated with
deep, oligotrophic waters.
Zone 2 extends tr"om 2-50
ct'n to ltlO crn and is
characterizecl by a sudden
drop
in cyst diversity
and
a switch
to simple.
unornamented
morphotypes. This
zone
is dorninated
é2-52c/c
relative abundance)
by
stomatocyst I (Zeeb
& Smol. 1993).
the sirr-rplest
cyst
rnorphotype, which
is
completely smooth
and lacks a
collar.
It is a comrnon
cosmopolitan type fitund
over
a broad range
of environrnental
conditions
(Duff et
al.. 199-5).
A collective
clitegory
cclnsisting of three
snrooth
cysts with simple
cylindrical
collars accounts
320
7y',ó l-o.2 0.4
0.6 o.B
1.O 1.2 1.4
Toïol
sum of squores
["igura J. Vclticll zonation of'chrvsophvtc
stomittocvsts in thc Rano
Raraku corc. showing ÍirLrr
zoncs
(zolrc:1
li'as Í'urthcr sLrhcliriclcd on
cr
idence ol' other nriclolirssils
).
for another
20-25c/c of the relative cyst abundance
in
z.one
2.
Zone
3
extencls from
180
crri to
130
cm and
supports
a sirnif ar cyst diversity to zone 2.ln this zone
.
howev-
cr. the relative abundances of cysts are
split
between
several
diÍÍèrent
rnorphotypes
inclr-rding
both common
cosrnopolitan types
(e.g.
cysts
l. l 10,
and
234
of Dutf
ct al..
loc.
cit.;, and
new rnorphotypes
which
are
not
present
in the chrysophyte
literature.
Zone 4 extends
frorn I
30 crn to the
top
of the core.
and covers both upper
zones
ol-ther
animal-
and diatorri-
based
zonation. It is characterized
by the
presence
of
all ten previously
described
cyst Ínorphotypes. Full
descriptions and stratigraphic
distribLrtions of these
cysts
will be
presented in
a
later piiper
(Zeeb
& Srnol.
in prep.). The new rnorphotypes
account
ïor 2l-40c/r
of cysts. Cyst
135
(Duff
& Smol. 1995), a morphotype
commonly fbLrnd in shallow. arctic
ponds
and other
cold,
low-water level situatrons
(Duff
et
al.,
1995) is
present
only
in
this
zone at U-30% relative
abundance.
A second
cold-water.
littoral morphotype.
cyst cf. l3zl.
Zone r'nf.lïcq
20-,
40,
Qnl
100
tlv 1
140
I i8o
2OO',
-1300-1450
AD
c
L
aLv
240:,
10v
2BO
)
?nn
is present
only in zone 4. Zone :l was noted tbr its
paLrcity
of total cyst abundanccs.
The screerrine
of the sedintent for ntacrofossils pro-
clLrced
abrrndant
leaf and stern
fragments
of kttrtru ttnd
Íut'uri dclwn to 135 cnt (inclLrcling
the fragntent
of
tut'ut'iused fbr r+C
clating). Nclt
a single fragrnent
was
filLrnd
deeper in the corc.
Zone zl of the chrysophytes
coincidcs with the
occLrrrence in thc core of Meyertiu
sp.
(s.1.).
a sponue
genus
(or group
of alliecl
genera)Íl'orn
North and Sor-rth
Arnerica.
as well as with that of rnost
diatolns. thc
grasses
plus
ruderals.
and
the ntacroscopic rerlains
of
Íoloru and tuyttt'i.
Diatorns were not totally rcstricted
to zone :1.
bLrt
wcre rare
below it (Table | ). Further'r.nore.
their proÍilc
upwards frclrl 135
crn was r.tot homogeneours:
besides
a nunrber
of wide-r'iurging
species.
with a large share
of aerophilic species
(in f)rct.
only three
species wcre
pelagic).
a cold-water species.
Acltttutttlte^s
cf . ubttrt-
tlrrtt.s,
appeared
above I l5 crl. This taxon is restrictecl
to
sorne
subantarctic
islands
(CocclLryt.
199 |
).
Another
species
not occLtn"in.u
below I l-5
crn was ly'if:.scltiu
cf .
vitloyit'ltii. a species
with a largely Ar"rstralian range.
althoLrgh it has been recclrded
once along thc coast
oÍ'Tanzania
(John. 1983).
Both species
contriblltc
to
defirre zone
5. Two other'.
possibly
significant species
conlnon to zones
;l and -5
are Nuyi<'ulu
goeplterÍiutttr
vttt'.
rttortiÍa
and Pirtrtuluriu
luteyittrrtri. Both are large-
ly SoLrth American
and. like the sprtnge Merertiu.Íhey
surddenly
becorne abundant
above l3-5
cnt.
Zctne
-5. in addition
to the distinctive
assernblage
oÍ'algal remains. is well charactcrized
by the rnicro-
Íirssils
of two crLlstaceitns'.
Alotur weirtet'ki.
a chydorid
cladoceran.
othcrwise
knorvn
only I'rorn
a
series
o1'sub-
antarctic
islands
(Frev. 1988t.
and Sanlcrpridop.si.;
ct.
eli,urbetltue,
àn clstracod front the subantarctic. Both
species
are cLlrrently
abunclant in the fl'eshwaters
of
the island
(Durnont
& Martens.
1996).
The rnagnetic
variables
(
1
. \ rr,,,.
SIRM and HIRM )
all reveal
an increasc
above 135
cni (FigLrre
4) (zoncs
l-3). sLrggestin-u
a decrease
in the
grain
size
of mineral
particles
in the or-uanic silt above
the inorganic siltv
clay layer. This is reinfirrced
by the firct thar the top
zone shows
risirrg
\.r,,,/\ and IRM reverse
values. indi-
cating a decrease
in the
grain
size
oÍ'the fèrrilnagnetic
fraction in zoncs
:l--5.
Fossil plant
pigrrents
(Table
2) inclucle r"rbiqLritous
corlpounds. but alscl signatr-rre pigrrients
of Cyanobac-
te ria
(echincnone
and zeaxanthin
).
Íiturnd in large qLlalt-
tities bekrw 135 crr. Fucoxanthin fl'oln diator-ns
ancl
piuments from anaerobic prokaryotes such as pho-
.115
tosynthetic
sulphur
bacteria and
sreen
chlorobiacean
bacteria
(bacteriophaeophi,tins
and chlorobactene)
occur exclr-rsively in zones
:1-5.
Our
Íirst
two
AMS llC uget
present
the samc
prob-
lcr-r.rs
r,rs
Flenley
& King's
(198;tt
Íbr Rano Rarakur
ancl Rano Aroi. i.c.
they appear mrch too olcl
(GIF
A
92327 at l6-5
cnr wÍrs l6 090
+ 170 BP: GIF A 9232u
at
220
cm
was
2.+
590
+ 310
BP) Íor sLrch shallow
scd-
irnent
clcpths.
Thc
thircl date. on
an
identiÍied fi-a-ument
of a known
plant
species. Polrcorrrun.
at 130-13-5
crn.
appears rnore reliable. Harcl-water
efÍèct was rcjected
bccausc
ol'a
low ri lrC (fnrnr lu to
-3r+
l).
typical of
a C3 plant.
the basalts in thc watcrshcd.
and
ntixing
of the
lake's water
by persistent
strong
winds.
which
maintains
eclLrilibrium between
atmospheric ancl dis-
solr,'ed
CO:. This
date. -588
+ 60 BP. after calibration
according to Str-river
& Reirler
(
1986). was
assisnecl
to
the interval l
300-
1.1-50
AD (95%
corrÍidence
interval).
Analysis of unsupported
llt)pp,
in saniples
between
100
and
135
crl depth revealed no signal significantly
diflèrent fronr zerc. Wc conclr,rde therefore
that scd-
iments at l(X)
cm depth
were
at lcast 150-200 years
old. witlr evident irnplications Íbr yearly
seclir-r-rcnta-
tion rates
(see
discLrssion).
Discussion
Basecl on Íbssils.
the crlre studiecl was
dividecl into
five intervals:
3'10-250crn. 250-17-5
crn. l7-5-135
crn.
135-ll5 crn. ancl ll-5 crn to top. Litholo-gically.
this
corresponded to thrce zones:
a lanrinated
inursanic
clay below
(3110-2110
cm). an inorganic
clay
(220-
135
crn). and a highly
organic
peat
on top
(
l3-5-0
cnr).
It was
frurn thc
bottorri 5 crr of the upper zone
that the
sterr
fragment
o1' ttttwri. dated to 1300 1.150 BP. was
isolatecl.
This
yiclcls
an average sedirnentation rate
of
0.7 and 0.1J8 rnm
y I tirl the zone
between
100
ancl
l
35 cm.
Ages
of c. I 6 000 BP
and
2'1000
BP Íirr layers
only
35 and 8-5 cm clccpcr'. respectively. wor-rld
con'e-
sponcl
to apparent sedimentation rates
of only 0.02-
0.03 mm y-1. ancl thereÍirrc
appear totally Lrnrealistic.
Also.
the sedirnent
below l3-5 cm was r-nainly
rniner-
al clebris
or. as the rlineral rnagnetic
properties
show.
coarse-grained.
We
agree
with
Klammin-ua
& Cotterell
(
lgull)
that,
like
in Flenlcy
& Kings'
(
198,+) study.
our two AMS
dates
arc unusable fur
establishing a
reliable
chronol-
o-uy. but sLrpport
the clccurrence o1'
a rather rnassivc
inwash
of carbon
cll'inÍinite age as
part
of cluarry debris.
A srnall
amoLurt
of rnodern
carbon is sr.rfficient
to rnake
416
'lhble l. I)iatonrs in Lake Rano Raraku
core ancl
in surface \\'ater
of Easter lslancl.
(C=Cosrnopolitan: ' lbuncl bclow l3-5
cnt)
Tuxa Rcccnt in In othcr lakes on
Rano RarakLr Easte r Islancl
Ccneral
distribution
OccLrrrcncc
in corc
'\ L
l t
t t t t
t t t I
t c,s L'.t i iq
t t t t G r u r
t. r' tu'. I t c t t, n n' t t I v t r Krasske
Ac lr t t tttrt
I
r t,.s I i r t r, u ri,r
(
W.Snr.
) GrLrn.
t\L lttttrttIIte.s
cf
. tt|ttrtttIutt.s
Man-ur-rin
i\ Lt I t t c
r
t.s
t' i
ru,q
n t
t
r r r I t t ! t t (
Eh r.
) S i tnonsen
Attluco.seirtt sp.
Culorrci.s but'illttttr
(Glun.
)
Cl.
C
t
x'L't
ttr
a i.t
1t
I ttc a tt I tt I tt Ehr.
(-
w' I t t t, I I u r t te r t e,q lt irr iurur Kii1z.
Ct'L ltIeIIu nttlitt.stt
(Gnrn..1
l.e nrnr.
C.t'L lrilallu s1't.-
Cvtt
ltc
I I tt cl'. h u.st cdÍ i í Krasskc-
Cvrrht,l lu lclttot'c
nt.s
(
Ehr.
) Kiitz.
[',pirln'ntitt utlttulu
(Kiitz.
) Bleíb.
F rugiltt riu (()n.\Í
rtten.\
1Ehr.) l'..rrrb.ríl1rlr(/
Hust.
()otrrltltrtretuu
purvtrltttrr
(
Kiitz.
) Kiitz.
Htrrrl,.sc|riu utttphirt-xt'.s
(Ehr.)
W.Sm.-
itlut'ictrlu utotitu.\ Kiitz. var.
ltenniÍi.s (Hust.) L.-fl.
Ir,/
ut' i t' t r I tr t t
tttÍ
c tt Ít t Grun.
iVttyictrlu
gteltlvrÍiurtu (Bleisch) H. L. Sniith
iV tty i t' tr I tr,,4r
rc
1t 1te
rÍ
i
tt tr
tt t ar'.
trt t
tn
i Ítt (
Hust.
) l-.- B.
iti tr t' i t' t r I tt trt
t t t
i
('
u Klil/..
i\t
uy iL'tt lu cl'.
1t
ltr
I lc
1tu Klitt.
Ir,!ttt'it trIu 1tu1tuItr
Ktrtt.
llit-.sL ltiu cï'.
vilttviL
hir Grun.
Nrt:.rr'/trrr lr/rrtr Nortrtan
(
)
rr I t t
t.s
c i
n r r(
)
(',\
( (
t t
l
(
t (
E,hr.
) Cral,'' Íirrcl
P i rr rr Lt I tt ri tr trt' n
t.sp
lrtte ri u Rabh.
P i rt tr tt ltt ri tr lx trt'tt
I
i.s Elrr.
PirtrrttIttritr lxtre
ttIi.s
l. rct'tuttgttItu
'r.r
Carlson'
P i t t r t u I u r i
u tl i
v
t'
r,qc t
r
t i.ssh irrr
(
Gru n.
) Cl.
I' i t
tttu
ltt ri
tt,gi
ltlut Ehr.-
P i tttt u ltr ritr I trtav
itÍttttt Cl.
P i t t t t tt I tt r i o tt tt,.st
t
I L'
pl
tr (
Ehr.
) W.Srn.
I' i tttttt
I tr
ritt vi
ri
I i.s
(
Nitzsch ) Ehr.
Rhi:tt.srtlenitt sp.
RItttltuI tttliu,qi blrc ru Iu (
Ehr.
) O.Mi.ill.
S Ítt t t ntt t c i.s r
t
bl t t su Lagcrst.
'l'lt
tr I tt.s,s i
t
t.s
i nr sp.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
C
cl
Subantarcl.ic
(.
L
C
C
C
(
C
C
(
t,
C
cl
C
C
S. Arnerica
C
L
t
Australia
(+ East AÍrical)
C
(
nrostll'
-l'rcpical
t
C
C
C
N. & S. Arncrica
C
C
C]
C
93 crrr
l2l e^rn
l0c) crrr
129 crr Il-5 crn
-l17
cnr l0l crl
-l0l cnr
-97
crn
I 17
cnr
105 crn
ll7 crn l0l crri
-l-15
cnr l13 crl
- I 65 crrr
ll5 crrr
l0I crrr
125 crn
-125
crn to top
315
cnr to top
12.5 cnr
-1.5 crn to tol-r
105 crtt
125
cnr
-97 crrr
12.5 cm to top
-l l3
crrr
- I 0t) cnr
-97 crl
l2-5 cnr to top
l2-5
cnr
to top
l2-5 cnr to top
-12-5
crn to
top
-16-5
crn to top
-l l7 cnr l0-5
crn
-3 l-5 crn
- l0-5
crn
-12-5
crn 93
cnr
ll7
crr l0I crl
- 1 f .5
crn
-93 cnr
-l2l cnr
-l l3 crn
-97
crn
-93 cnr
-I 33 cnr
+
a sample
of infinite age
appeiir
Íinite. i.e.
c. 30000
years
old (Olsson.
l99l). It is noteworthy that Flen-
ley & King (19U4)
originally
rejected most of their
IrC
dates on similal'grouncls,
but later accepted them
(Flenley
et al., l99l). perhaps
because they show a
weak
statistical increase
of age with depth below a
break in the seqLlence. identical
to the one revealecl by
oLlr core and
sitLrated in theirs at 0.9-1.0 m (,180
+ 60
BP). This
date
is
well
in
line with
oLrr 588,l60 BP
at
I 30- I 3-5 cm. Only
20
crn deeper,
however. Flenley et
al.
record a r'+C
age of 6850
+ 50
BP.
We attribute the inwash
of old carbon and coarse
rnineral particles, to the
quarrying
of ntoai, which may
have produced a layer of sediment thicker than any
411
Tublc 2. Signature
photosynthetic
pi-urncnts
lirund in the Lake Rano Raraku
core
Pigrrent
(trr,-e
g-l Dw) 88
at diÍlèrent
clepths
(crn)
in
core
-90 -107 -ll0 -11.5
-t!t -130 -13.5 l-12 16-5 190 -205 -22-5 -24-5 3(X)
chlorobactene
biictcliophaeophvtin
(anaerobic
Bactcria)
t'Lrcoxanthin
cliadinoxanthin
(cliatonrs
)
cchinenonc
zeaxanthin
(Cyanohacteria)
l'iolaxanthin
lLrtein
0.-5 l0l trace (l)
trace 0.89 trace (
I )
(l) tracc (l) (l) trace
(l) trilce (l) (l) tftlcc
lrlrec ().18
0.15 0ll () () -s0 8l
1a
+.+
2-5
I
18 .+l
29 -530 32-s
t.t(x)
1213.5
l3
(-): bey'ond
detection lo,el.
core so Íar lifted fiom the
lake
bed. It would
definitely
be of interest
to try and
core to well beyond this layer
in future.
and
see if younger
laC
chtes reappear
there.
The
top of the
quarry
debris is well defined. It is
situated
between 100
and 120
crn in core RRA3 of
Flenley
et al.
(1991),
and
at 130-135
cm in our
core.
It is accompanied
by a number
of concurrent.
sud-
den
changes in the
paleobiology
of the
lake.
such
as
the appearance
of totorct
and tor,ori
(the latter neat-
ly confirmed
by the
pollen
distribution
of Po1.r'gotlutn
in core RRA 3 of Flenley
et al.
(1991);
traces krwer
down
may be due
to hand
coring).
the sponge Met,e-
rtict
sp.,
the diatom s Nnviculct goeppertiotto
var.
monitu
and Pinnuluriu
lutet,ittutu,
zone
4 of the chrysophytes,
and
anaerobic bacteria.
All fully identified
species
are
of exclusive
or dominant American
origin. For
a dis-
cussion of the
biogeography
of the
totonr. see Heiser
1911, 1919.
Although
Flenley
et
al.
(1991)argue
Íor
the
presence
of this
species
on the island fbr at least
the last
30000
years.
this
claim is based on accep-
tance
of questionable
laC
clates
and
on distinguishing
the pollen
of Schoenoplec'tu.s
front at least four oth-
er species
of Cyperaceae
on the island. Flenley
et al.
(
l99l )do
not
provide
evidence
fbr
their identification.
We
thus regard
our record
of macroÍossils
as
more
reli-
able and
conclude
that there is no proof
of the
presence
of totrtra
on Easter
Island
before
the l4th
century.
Because
of the synchronous
appearance
of multi-
ple taxa
above
l3-5
cm. we rule out that they were
introduced
passively,
by wind or birds. Most of the
diatoms
are either
epilithic
or epiphytic,
and the Meye-
nra sponge
also
grows
on water
plants.
sr-rggesting
an active
importation
of whole plants
(along
with
their epibiota) to the island. Furthermore. we note
the
absence of South American
elements
from
the
terres-
trial
fauna
of the
island
(Kuschel.
1963). such
th:rt,
should anemochory
or zoochory
have occurred.
they
were
strongly
biased to fl'eshwater
elements.
a sitr"ra-
tion
which is
hard to explain. in view
of the distance
to be traveled. and the
absence of freshwater
birds
on
the
island.
We
therefore
propose
that humans introduced
these
neotropical
biota. in one single
event.
There
was
il
later wave
of introductions
at c. ll-5 cm. i.e.
the top
of the transition zone.
Once a,sain there was a sudden.
simr,rltaneous
appearance
of diffèrent taxa, this tirne
involving
a cladoceran
(Alona
vreinecki).
an ostracod
(Sur.sct'prídop.sis
cf . eli.sabethtte).
two types of cold-
water
chrysophyte
cysts. and two
diatoms,
Aclutunthe.s
cÍ. nhuntlnn.r and Nit:.schiu
cf . yidovichii.
The twct
crustaceans and the Achnurttltes
are of Íar southern
(subantarctic)
origin.
the
l/ir:^rc'hia
rs. in all
probability.
Australian.
Both
crLlstaceans are
currently common
in
the
island's
freshwaters. where
they were recorded
in
1990.
and again in 1993
(Durnont
& Martens.
1996).
While
the south American invasion
event
was
laC
dated to I 300- 1450 AD. the sr,rbantarctic wave
can be
dated only approximately.
Applying
the
sedimentation
rate
of 0.7 to
0.88 mm
y-r upwards from
135
cm. leads
to a date between 1527
and 1685 AD. fbr
the horizon
at I l5 cm. Downwards from I l0 cm
we
arrive
at dates
between 1586
and l6U0 AD.
,+
l8
Applying a unilorm
sedimentation rate between the
top oÍ' thc core and l3-5 cm is probably incorrect. For
thc
scrni-liqLrid
peat. which we
discarded.
Flenley et al.
(1991)
arrivecl at an accLrr-nuliition rate of c. I cm per
1,ear.
If we accept this. then the 8-5 crn of cliscarded
peat
represent
about 8-5
years: burt
if the age at 100 cnr is
l-50-200
ycars
as su-tgestccl by rlt)p6.
this wourld meiln
a
rate
of |
.3 to 2.3 mm per year
for the
zone between 8-5
and 100 crl. Cclmpaction thus
probably
caused a
strong
vertical decrease in apparent sedimentation
rates. It
firllows that our extrapolated dates of AD c. 1680 at
I l5 crn
rnay be too old.
Wc cxplorccl
the historical rccords to see
whether
there are ckrcLrrnentccl
historical
events that might cor-
relate with the irnnriglutit)n wllvL-s
rt I l-5 and l3-5 crn.
The Íirst European visitor to thc islancl
was Jacob
Roggeveen in 1122. Htwtn-u
crossed the Atlantic. he
sailcd along thc coasts of SoLrth America. halting in
Rio cle Janeiro to take in freshwater.
He then proceecl-
cd across the Falkland Islands
(a site
fl'om which A.
weitrccki is knorvn)"
but did not stop there. ror-rnding
Cape Horn to land again tor water at Juan Fernan-
dez Island
(FigLrre
-5). His visit to Easter island
was
brief: only a single day was spent
on land. but by
about
130
people.
and there
was
cert:.iinly contact
with
Iocal inland water. which was described
as 'tastin-u
brackish'
(Mulert, l9ll). The second visitor. Felipe
Gonzalez
(in 1770)
came
strai-uht frclr.n mainlancl Peru.
Forrr years later,
on ll March 1111. Captain James
Cook rcached thc island. He had sailed tl'onr New
Zealand
to subantalctic wrters in search of the myth-
ical Austral continent.
Having takcn water on hoard
in Ncw Zcaland, his ships had remainecl out ol'sight
of larrd firr 102 days. occasionally replenishing their
watef
reserves by collecting ice frorn Íloating icebergs
(FigLrrc
-51. On Easter Island. his crew collectecl
thrce
casks oÍ'Íl'cshwuter
(scc
Beaglehole. 1961. lbr
the
ÍLrll
rccrlrd
ol'Cook's
journals).
No dor-rbt. these casks
were
rinsed well befbre being filled and. hcnce. all livirr-u
or restirlg sti"lges
of planktclnic
organisms
pr.esent
we|e
washed out. The trajectory o1'
Cook was fully with-
in the range
of A. weitrcr'fri
and the other subantarctic
biota now occurring on this subtropical island.
Rest-
ing stages may have
been
present
in the ice collected
(n ft)ute. bLrt it is also possible
that the contarnina-
tion
occurrcd during Cook's long stay on South
lsland.
New Zealand. There irre no pLrblished
records of A.
vrcirrecki ll'onr New Zealand.
br-rt
the late D.G.Frey (ri
/ir.) discovercd specimcns on Macqr.rarie Islancl. That
Cook's visit rrray be at the origin of Easter Islands'
prcscnt population is reinfilrced by the sintr-rltaneoLls
introducticln
oÍ' the Australian Nit:..scltiu
t'itktt'iclti i.
IÍ-James Cook is thr"rs
likely to have introdr-rced
the subantarctic asserr-rb
I
age of tnicroorgan
i stns.
Jacob
Roggcvcen cannot be exclucled. Infbrmation on the
zoclplankton of Juan Fernandez wor-rld be welcotlc.
Many sixteenth and scventeeth century
sailors indeed
stopped
at the
Falklands. and Juan
Fernandez
may havc
rcciprocally contarninated
the
planktot-t of both islancl
groLlps prior to Roggeveen s visit. Whalers
are
another
possible source of introductions. but they
only becatne
actir,'c at the
close o1'the
lSth and dr.rring thc l9tn
cen-
tury.
which postdates
thc deposition
of sedirtient
at the
l l-5 crr depth.
Because
pollen is
allochthonous.
its
distributictn
in
the lake sedirnents
is not necessarily
linkecl to events
that charactcrize
the autochthonous
biota. Yet. like
Flenley et al.
(
l99l ).
we noted
a
substiintial
increase
of
-grass
polle n frorn l3-5 crn upwards.
inversely relatecl to
the
quarrtity oÍ'palrn
pollen. This
Jubuca
pollen
occLn's
until well aÍtcr the
first E,urclpean
visits. and is cclrrobo-
rated by si-uhtings
of srnall
'coconut'
trees
(doubtlessly
Jubueu) by Cpt.
Bouwrnan ol'Roggeveen's
party.
Even
well into
the l9th centLrry. boles
of decayin-e
palrn
trees
wcrc seen on the island by sorne visitors
(e.g.
Palmer.
IU70). Sorne
palmtree fl'uits. Íirund in caves on the
island. have been dated
to the lTth centurv
(Arnold et
al.. 1990).
The qr,rcstion
then arises
what caLlsed the wavc of
inrrni-tration
(ancl
the change
in pollen)
at 135
crri'l
In
ten'ns of diversity
introdr-rccd. it is ntore
irrportant than
the subantarctic event
at I l5 cm" and
suggests that the
aquratic biota
of the
island.
prior
to the l-lth- I
5tr'
centu-
ry.
were
even
rrol e depauperate than today.
with alrnost
no anirnal
elernents
present.
This confilms
once again
that the island
is so ren.rclte. and
such
a srnall target. that
nrechanisrls of p:lssive
dispersal
were ine l'fèctive for
populating
it. The nrost
pat'sit.t.ttlrtioLts
explanation
for
the Sor-rth
Arnerican wave. which clearly predates
the
arrir,'al of the Europeans.
mi.elht
be an introducticln by
seaÍaring
people frorr Peru
or Chile. Hcrc. we touch
upon the controversy arron-q archaeologists
and eth-
nologists,
with Heyerdahl
(
1952. 1951
.1980)
clairning
that there
were early contacts between
South America
and Easter Island, and that its first irtintigrants ciure
frorn the east.
This thesis has been under
severe
attack
by nrainstream ethnologists-archaeologists.
A sutnnia-
ry of their
view
can
be lirund in Bahn & Flenley
(
199l
).
who -ucr
to grcat
len-etl"ts to praise
the
navigational skills
of the Polynesians.
These people presumably reached
Easter Islancl clurinÍr the 5t'' centLlrv
AD.
119
'-a
z.a
ry.:
=
;t
:-=
-?
z.<
a/ z.
=d
-a
,í *>
=-
U/
t
=-\
--
')/
at
E;
,,'
z'?.
v,t
7 z,:
-:
,' )
í2
tj
-=
= r')
_a^
a-_
tl
!a
--^
3l) Á
-'a
2-
?=
Jn:
?v
?.
^a
i+.
:1 \
'=--
à,==
:.-
.J-
=t!
trr "r :
c.)
ín
L\J
o(o
obq
L_ v
LJ
É"
O
N
o
É. ï ^
a,Éï
Èb o
-t3:+
s'"
5N
X
O
j-
Ior
-Y
É.€
6
-rl O r^l
x
^ f.)
ïct)
-v
v.à
atrto
rN
c'r
>#
{-E r
><b
io
ïN
ol
!
n
X.E -
!o
x
-o
O
o
N
O
O
(..) r.ltdê0
lrl
z.
o
I\I
lJ-l
-.
O
I,J.J
=,
o
l\l
lrJ
-.
o
lrJ
-.
o
I\{
O
420
Írl
I
J
-c
2
È
)
-
z
f,4
However,
the Polynesian
theory raises
two impor-
tant
questions:
First. if they were highly
skilled navi-
gators.
why did they not extend their explorations
as
Ír.rr
east as South Arnerica'l
Second. what about
the
navigational
skills
of the Amerindians?
Historical records.
lacking
tor Polynesia.
are
of
considerable help in
South America,
since the
Spanish
conqLrest in the l6th century was rapid, profbund,
and
left us with detailed
chronicles. Two of these. writ-
ten independently
and using
difÍerent sources. were
by
Sarmiento
de Gamboa
(1572)
and Cabello
de
Balboa
(l-5U6).
Both relate.
in
considerable
detail,
the
voyage
of the
Inca
prince
Tupac
Inca Yupanqr-ri.
west into
the
PaciÍlc.
This
journey.
said
to have involved
200
bal-
sa
ships
and
20
000 men.
lasted for about
one
year.
Its
timing,
three
generations
befbre
the arrival
of the
Spaniards. places
it in
the second half
of the l4tr'
centu-
ry.
compatible with
the
introductions
noted
by us.
The
Inca
trip was
prompted
by the fact
that trade had long
existed
between
the South American
shorelands
and
sailors
coming across
the Pacific.
This suggests
that.
not only had
the Polynesians
crossed
the
PaciÍic,
but
they
were
capable
of doing so on
a
regular
basis. Thr.rs,
it would
be surprising
if they had no knowledge
of the
existence
of Easter Island
and did not.
at
least
occa-
sionally. visit
it. Conversely,
Amerindian
sailors may
also have visited
the island.
That
the Incas,
through the
coastal
people
they had
subdued. were
indeed
capa-
ble of complex maritirne
expeditions
is confirmed
by
authorative soLrrces.
Buse
(1911)
provides
a detailed
description
of large
balsa ships with one or several
masts.
and living cabins roof-ed
with tcttoruL
(l) and
other
plant
materials
that
were
used on such
expedi-
tions. Such ships were
capable of sailing against
the
wind.
There is
one other fhct
tit which
surprisingly
lit-
tle attention has
been
given.
When Roggeveen
arrived.
thc islanders
showed
neither
Íèar nor surprise
at see-
ing
such large
ships,
but
rather
measured
their length.
although
being unacquainted
with
such
objects as nails.
mirrors.
and musical
instruments.
The
suggestion
here
is that, frorn
time to time. visitors
Írom outside had
been ashore
at the island
before
the
arrival of E,uro-
peans.
Had
TLrpac's
entire fleet
landed
on Eiister Island,
verbal
ilccoLrnts
abor,rt this would
almost
certainly have
becn
handed
down. Yet,
it is unlikely that
all balsas
stayed
together. and
one, or
a
few
may have
stranded
on
the island.
by then already
largely
deforested
(Flenley
& King. 1884).
The presumably
small number
of rnale
Indians
may have
left
an
as
yet
undiscovered genetic
121
imprint.
but their signature is still seen in
the biota they
i nvoluntari ly imported.
It is intriguing
that this
wave
of introductions
coin-
cides
with
the end of Íhe
tttocri
carving, which
changed
the lake environment
deeply.
From deep
and rather
oligotrophic
durin,s
phase
l. it evolved into a turbid
enl
ironment,
in which mainly Cyanobacterizr
flor.rr-
ished
(leaving
the
signature pigrnents
echinenone
and
zeaxanthin),
and
then
back into a shallow. clearwa-
ter
lake rich
in diatoms
(producing
fucoxanthin)
and
with
a
littoral
fringe of Íotoru. A bottorn
mat
of decay-
ing water plants
created
an anoxic
benthic zone. rich
in sulphr.rr bacteria
and green
Chlorobiaceae. lt is
tempting to assume that the
Incas.
even if incapable
of escapin-9 from the island. besides
planting
toÍoro
and Íttvttri, halted
the tradition of carvilrg
giant
stone
images. Whether
this eqr-rates to the period
of tribal
conflicts which
eventually destroyed
the
island's
cul-
ture.
an event
which genealogy places
at c. 1680
AD
(Englert.
1948). renrains
cn open
question.
Should it
be
conÍlrrned by independent
evidence.
however.
it would
mean
that the so-called rniddle
period
ended
earlier
than hitherto
believed.
Acknowledgements
The Íield work tbr this study was Íinancially
support-
ed by the National
Science
Fund. Belgium.
We
thank
our colleague Dr S. Cabrera
(University
of Santiago.
Chile) fbr his assistance
in preparing
the expedition
and during the field campaign. We
also thank Patrick
Dumont
and Dirk Verschuren Íbr help in carrying
out
the
corin-e. Lilian Gonzalez
(Hanga
Roa)
made neces-
sary logistic
connections
on the
island.
Mark Brenner
and
an anonymous reviewer made numerous
construc-
tive
remarks
on an earlier draft. The Flemish
commer-
cial television
(VTM)
videotaped
the coring
operation.
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c1.r : ll8 120.
Srrrith. Cl.
S..
196 lb. Radiocarbnn clatcs
lhrnr Eustcr lslancl. In T. Hcy'-
erclahl & N. Fcrclon
Jr.
(ecls).
q.r.:
393-396.
Steaclnrarr.
I). W.. 199-5. Prchistoric extinctions o1' Plcilic Ishncl
hircls:
bioclilersitl'
nreets zooalchacolo-u1'. Scicncc 1667: I l13-
ll3l.
Stuiver. M. & P. J. Rcirncr'. Ic)8ó. Conrputcl
pr'osranr
f'or rarliocarbon
agc calib|ation. Radioca[bon
]8 (lBt: l0l2 1030.
Zccb. B. A. & j. P. Snrol. lc)93. Chn,soplrvcean
stonralol,sl Ílora
ll'onr
F,lk Lakc. Clcaru'atcl Countr'.
Minncsota.
ClLn. J.
Bot.7l:
1 31
-1
56.
