1984

1807

mt.

st.

Hel

ens

1801 1794

1789

laki

178

3

1774 17

72

1763

tar

um

ai 1

739

1730 kr

aFla

172

8 o

rae

Fajo

kῡll

172

7

myv

aten

Fir

e 17

24

1721

kat

la 1

721

1719

Hel

ka 1

693

katl

a 19

18ta

mbo

ra

1815

1813

katm

ai 1

912

1909

tun

gu

ska

even

t 19

08

tar

um

ai 1

667

katl

a 16

6018

98

1896

1888

*

1885

WH

ite

riv

er a

sH 1

885

krak

a tau

188

3

1877

1876

Fur

nas

163

0

katl

a 16

25

1864

WH

ite

lig

Ht

Flar

e 18

59

sHev

elu

cH

185

4

cH

iku

rac

Hki

-tat

arin

ov

1853 18

51

1849

Hel

ka 1

597

co

siq

uin

a 18

35

babu

yan

cla

ro

183

1

1991

1990

1989

st. a

ug

ust

ine

1986

saku

ra-

jim

a 19

77?

1974

1972

Hek

la 1

970

sHev

elu

cH

196

9

1963

1962

n

ova

yaze

mly

a 19

61 H

-bo

mb

test

askj

a 19

61

1960

1958

1951

1949

Hel

ka 1

947

1942

1941

Plates ia and ib

micro-resolution records of simultaneous nitrate concentrations in relative units (bluecurve) and liquid conductivity (orange curve)from the central greenland ice sheet. the x-axis is proporational to the true depth belowthe surface (122m) and has not been adjust-ed for compaction. nitrate background dis-plays a prominent seasonal cycle. the nitrate anomalies are apparently caused in mostcasas by individuals solar particle events(dates have been marked in blue). black ar-rows at the bottom of the graph indicate timesof sunspot maxima (up) and sunspot minima(down). the numbers at the top of the graph indicate the approximate summer peaks ofthe years of the most recent maximum insolar activity. asterisks next to major peaks indicate that these anomalies are part of theongoing evaluattion programs. areas of gray shading represent portions of the core resam-pled for confirmation. Absorbance units (100 x 10-4 ) convert to 20.4 μg/l NO3-N or 90.3 ng/g no3. anomalous conductivity peaks indicate the years of specific volcanic eruptions.

1929

1928

rai

koke

192

4

1922

Hel

ka 1

693

tam

bor

a 18

15