History of Geophysical Research in The Netherlands ... - DWC - KNAW

the North Sea and in the Atlantic Ocean. In the beginning especially the bathymetry
of the sea bottom was determined, but later on also the structure of the
sedimentary layers and the geomagnetic field. Soundings of the ocean bottom
by the Marine Geophysics Group are discussed in the chapter on seismic research,
and the gravimetric measurements in the chapter on gravity. Below a
summary of the geomagnetic research is given; the results were presented in
a series of publications and a number of doctor's theses.
In the years 1964 and 1965 the Royal Navies of Great Britain and the Netherlands
, in cooperation with the U. S. Naval Research Laboratory , carried out
extensive oceanographic research of the Atlantic Ocean under the name of
NAVADO Project (North Atlantic Vidal and Dalrymple Oceanography). At the
request of the organizing committee the Netherlands took part in the third
phase of this project by making available H. NI. M. S. Snellius. The Snellius
crossed the North Atlantic ten times, and made possible measurements in a
region between 22°N. and 49°N. latitude. Collette and his co-workers (R.A.
Lagaay, A.P. van Lennep, K.W. Rutten, J.A. Schouten, R.D. Schuiling, F.W.
Warnaars and C. H. van der Weijden) were responsible for the geomagnetic measurements,
making use of the proton magnetometer of the KNMI. Gravity measurements
were carried out by G. L. Strang van Hees and T. J . Poelstra (TH at
Delft). Recordings of the bathymetry, the geomagnetic field and the gravity
field have been published by the Hydrographer of the Royal Netherlands Navy
(Anonymous, 1967). The Netherlands Organization for the Advancement of Pure
Research (ZWO) gave ample financial aid.
During these voyages between Europe and America, Collette and his colleagues
tried to measure the heat flow at some places at the bottom of the Atlantic Ocean,
but these measurements were not completely successful (Collette et al., 1968).
I. 8. 3. Atlantic Ocean: Kroonvlag Project
The NAVADO Project was followed by the Kroonvlag Project (1967-1980),
again with considerable financial aid by ZWO. This project aimed to carry out
geophysical measurements aboard freighters of the KNSM (Royal Netherlands
Steamboat Company) and the SMS (Suriname Shipping Company). The name
Kroonvlag (Crown-Flag) was derived from the Company's flag to which these
ships belonged. A group of marine geophysicists of the Vening Meinesz Laboratory
crossed the North Atlantic Ocean more than 40 times and made a dense
network of geophysical measurements over the Atlantic between 6°N. and 37°
N. latitude. During the crossings the bathymetry, the structure of the ocean
floor, and also the strength of the geomagnetic field were determined. The result
of the magnetic measurements can be found in a publication by Collette et ...
al. (1974). The following scientists cooperated in this research: K. W . Rutten,
J.A. Schouten, A.P. Slootweg, W. Twigt and J. Verhoef. One of the results of
the Kroonvlag Project was a detailed survey of the Mid-Atlantic Ridge, especially
of the fracture zones and the central rift zone. Collette (1974) explained
the fractures in ocean ridges as shrinking cracks in the cooling oceanic crust.
1.8.4. Atlantic Ocean: Vaarplan Projects
In 1977 a new period for oceanography in the Netherlands commenced with
the commissioning of the research vessel H.NI.M . S. Tydeman. It was built to
replace the hydrographic vessels H.Nl.M.S. Snellius and Luymes (see Chapter
11, section 7.5).
A scientific program, Vaarplan (Sailing Scheme) 1974-1978, followed by Vaarplan
1978-1982, was developed by the Netherlands Council of Oceanic Research
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