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3.1. The Borobudur Lake 
The discussion about the existence of an ancient 
lake near and around Borobudur was started in 1931 
by the famous painter W.O.J.Nieuwenkamp, who had 
spent several years of intensive studies on Hindu- 
Buddhist architecture, in particular on the Island 
of Bali, and who also visited Borobudur several 
times. As an artist he visualized Borobudur, sit 
ting on top of its hill, as a "lotus flower 
drifting on a lake, on which the new-born Buddha 
was seated". Support for this idea is found in the 
conventional lay-out of Buddhist sanctuaries, very 
often surrounded by a moat symbolizing the cosmic 
ocean from which the earth was created. Typical 
examples of such moats exist around the various 
temples of the Angkor Vat complex in Cambodia, 
whereby it should be remembered that the Buddhist 
Khmer civilization of Cambodia was much inspired by 
the older Javanese Hindu-Buddhist traditions. 
Modern examples are the ponds with their lotus 
flowers, so often found in front of the Balinese 
temples. 
Several geologists took part in the debate which 
was carried around 1933 in the monthly journal 
"Nederlandsch-Indie Oud en Nieuw ", and the daily 
paper "Algemeen Handelsblad", Amsterdam, in par 
ticular the two friends Prof. Dr. L.M.R.Rutten and 
Dr W.Nieuwenkamp, the latter son of the painter. 
Furthermore, persuaded by W.O.J.Nieuwenkamp , 
Cr.Ch.E.A.Harloff and Dr. A.J.Pannekoek carried out 
a serious geological and geomorphological study, 
first reported in 1937 and finally published in 
1940 (Harloff and Pannekoek, 1940 ). The subject 
was studied again in 1966 by two Indonesian 
hydrogeologists (Purbohadiwidjojo and Sukardi, 
1966). These studies confirmed that a lake could 
have existed here in pre-historic times, filled up 
by at least 10 metres of sandy-clayey alluvium. 
It is true, the hill on which Borobudur stands, 
consists largely of man-made fill requiring a 
borrow-area of fair dimensions. This could have 
created a new, although artificial small lake at 
the time of construction of Borobudur (Soekmono, 
1969, 1976). However, the study of large-scale air 
photos of the Borobudur site, undertaken in 1968, 
failed to reveal traces of such a major borrow- 
area, which once could have formed a large pond or 
small lake corresponding to the moats found in 
Angkor Vat or the ponds in front of the Balinese 
temples (Voûte, 1969, 1981). 
Moreover, soil samples taken from archaeological 
trial trenches on Borobudur hill and on the plain 
immediately south of it, were analyzed for their 
content of pollen and spores, in order to obtain 
information on the vegetation of the area surround 
ing Borobudur at the time of its construction and 
immediately thereafter. No indications were found 
of a vegetation characteristic of an aquatic en 
vironment (lake, pond or marsh); on the contrary, 
Borobudur at the time of its construction appears 
to have been surrounded by agricultural land and 
palm trees as is still the case today 
(Thanikaimoni, 1977, Dumarçay, 1977). 
3.2 The eclipse of the Mataram Kingdom 
The second theory refers to an entirely different 
phenomenon. Formulated in its final form by Dr. Ir. 
R.W. van Bemmelen in 1949 after a first publication 
in 1941, it is based originally on a translation 
and interpretation of ancient Hindu-Javanese 
Sanskrit texts by the archaeologist van Hinloopen 
Labberton (Van Bemmelen, 1941,1949). In a study 
published in 1921 the apparent destruction of the 
old Mataram State in the Sjaaka year 928 
(equivalent to AD 1006) was assigned to a "Maha 
Pralaya" (natural calamity of terrible 
proportions), interpreted as a major volcanic 
eruption accompanied by intense rainfall and very 
extensive flooding, during which King Dharmawangça 
and many people of high standing and noble birth 
died. The King’s son-in-law, 16 years old, escaped, 
and under the name of King Erlangga ("He, able to 
escape the floods") , founded a new kingdom in east 
Java, which under the name Daha (Kediri) continued 
the Hindu-Javanese traditions in a modified form. 
This found its apogee in the 14th century in the 
empire of Modjopahit (also in East Java). 
Meanwhile, during two centuries the ancient sources 
kept an absolute silence on once flourishing and 
densely populated Central Java (Van Hinloopen 
Labberton, 1921). 
Van Bemmelen, who had formulated new hypotheses 
about geology, including the role of gravity- 
induced large-scale sliding movements in relatively 
recent times, interpreted this calamity as a 
cataclysmic outburst in 1006 AD, of Merapi Volcano, 
depopulating, desorganizing and destroying the 
prosperous Hindu state of Central Java , and con 
verting its fertile fields into grim deserts of 
ashes and mudflows (lahars). This outburst would 
have been accompanied by the collapse of much of 
the western slopes of Merapi, which slided down 
along slipfaults, pushing up the Gunung Gendol 
hills south of Muntilan village, blocking the Kali 
Progo valley, and through this damming up, flooding 
the Borobudur area by a large lake (van Bemmelen, 
1941, 1949). 
The volcanic cataclysmic theory has remained very 
popular with the Indonesian archaeologists as a 
rational explanation for the shift of political 
power and architectural/cultural activities from 
Central to East Java (Boechari,1976, 1976/82, 
1977/82; Moendardjito, 1978/82; Soekmono, 1976). 
They were convinced to have found further confirma 
tion when the various archaeological trial trenches 
made in the surroundings of Borobudur from 1973 
onward showed the presence in several places of an 
ash layer from a few millimetres to a few cen 
timetres, and locally also a 30 cm. thick layer of 
sand, below which there occurred to a depth of 1 
metre, occupational soil with many potsherds of 
Indonesian and Chinese manufacture (Boechari, 
loc.cit; Mandardjito, loc.cit ; Voûte, 1981). 
However, this sand layer could very well be the 
product of local downwash and sheetfloods from the 
Menoreh Hills somewhat farther South. In any case 
the accumulation of soil and debris of a magnitude 
as found here, need not put an end to human occupa 
tion, as is quite evident from the fact that the 
layers with potsherds and other artefacts, sign of 
regular religious festivals over a period of about 
two centuries, are rather thick. 
Some other evidence also pleads against the deposi 
tion of large masses of materials (pyroclastics and 
lahar deposits) during the ill-fated year of 1006 
AD of the old chronicles and descriptions. In the 
districts immediately surrounding Borobudur no less 
than 207 archaeological sites have been inven 
toried, including the remains of 43 temples 
(Voute, 1975/82) , none of which are deeply buried. 
At Mendut temple, east of Borobudur, several feet 
of ashes and lahar deposits had to be cleared away 
to reach the original surface of the temple square, 
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