Meded. Werkgr. Tert. Kwart. Geol. 25(1) 7-10 1 fig. , maart 1988

The Zuurland borehole: introduction

by

Leen+W. Hordijk Brielle.

Hordijk. Leen W. The Zuurland borehole: introduction.—Meded.

Werkgr. Tert. Kwart. Geol., 25(1): 7-10, 1 fig. Leiden, March 1988

The previous history and a concise description of the drilling techni-

ques applied for the borehole Zuurland-2 at Brielle, province of Zuid-

Holland, The , are given.

L.W. Hordijk, Annahoevestraat 69, 3232 VB Brielle, The

Netherlands.

Contents Samenvatting, p. 7

7 History, p.

Methodology, p. 8

10. References, p.

Samenvatting

De boring Zuurland: inleiding.

introductie de hierna artikelen worden in het kort de de Als op volgende voorgeschiedenis en

Brielle. toegepaste boortechnieken beschreven van de boring Zuurland-2 te

HISTORY

As I curious learn about the Earth below feet and I the a young boy was to our investigated upper-

in the of the of Oostvoorne the island of Voorne-Putten with most layers area village on very primitive drilling equipment. It was impossible for me to arrive at levels below 10 metres below the surface because the successive boreholes continuedto collaps. The application of casings and a pulse with a valve was not only unknown to me, I could not have afforded such equipment either.

In 1969 I obtained drilling equipment with a pulse. During that year I reached a depth of 25

in available 44 metres and 1972, using all casing, even metres.

work the In 1979 I obtained a piece of land in the polder Zuurland where I could on borehole

After of I in of 1980 for a longer period. buying a large quantity expensive casings made, the period

of to 1983, a borehole with a depth 95.02 m. 8

I studied the lithology of the sedimentary succession and paid only little attention to the remains of flora and fauna. On the one hand much material was lost because of the use of a sieve with a mesh of 5 and the hand I the value and the the mm, on other was not aware of significance of fossils.

Although I had some literature about mammalian fossils I did not realize that there could also be

fossils the which in layers I was investigating. Nevertheless, I noted the presence of shells. I divided

them into two categories: those with smooth and those with ribbed surfaces.

which I did hand and without I into contact During my drilling activities, by any help, came

A.C. with Mr Janse from the city of Brielle. He showed me a better way to take my samples and he also into with other who fossils. brought me contact persons (professionally) studied Quaternary

This resulted in the of The a visit to Geological Survey Netherlands at on the 11th of

November 1982. Since then the investigation progressed rapidly.

With the knowledge of the lithology and realizing that the sampling had not correctly been

I executed, decided to start all over again and make a new borehole close to the previous one. I started

the 2nd 1984 and I that it will still take several on February expect years to complete (Hordijk, 1985,

The first results called 1986). of this "new" borehole, Zuurland-2, were presented at a symposium, held the 14th of 1986 The the various contributions on November (van Kolfschoten, 1986). texts of are printed in this special volume of 'Contributions to Tertiary and Quaternary Geology'

( = 'Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie').

METHODOLOGY

The drilling technique applied is a bailer sampler. The equipment consists of a pulse: an iron pipe

1.5 diameter 7 with valve the and in with of 2 (length m, cm) a at bottom, casings pieces a length

and 3.5 9 attached with wire and metres a diameter of inches (almost cm). The pulse is a synthetic brought into the casing. After dropping the pulse several times from a small distance above the bot-

of the it fills with sediment is of the tom borehole, gradually up and pulled out casing. By preventing

the it is let the sediment well and take from casing to sink, possible to up large samples particular

that the this borehole layers. Therefore we must realize large quantity of fossils from cannot be com- pared to the results of other, "normal" drillings.

For further is taken from of the section. investigation an unprocessed sample every metre Special attention is paid to the sampling of clays, claystones, gravels and wood. Most of the collected sedi-

is washed mesh is done the The ment on a 0.4 mm sieve. Sieving near borehole. residue is dried

and sorted binocular at home out with a microscope followed by a provisional identification.

The fossil of the section well other material is the content as as registered per metre. Lumping

metre realize that in certain thin with different contents per we must some cases layers a (fossil-)con-

fossils be with sections tent or thin layers without can not recognized. This is the case at a depth between -22 and -23 -23 and -24 -28 and -29 and -36 and -37 In the of the m, m, m m. description lithology and the fossil contents this will be discussed further. 9

Netherlands. Fig. 1. The Zuurland-2 borehole at Brielle, The R.G. General impression of the drilling equipment (November 1987). (Photograph Meijer). 10

REFERENCES

Hordijk, L. W., 1985. Verslag van een grondboring in de polder Zuurland nabij Brielle, 1. Het traject van

Brielle 0 tot 20 m diepte. (unpublished report), 156 pp.

Hordijk, L.W., 1986. Verslag van een grondboring in de polder Zuurland nabij Brielle, 2. Het traject van

20 tot 40 m diepte. Brielle (unpublished report), 237 pp.

1986. Van Kolfschoten, T. van, Uitreiking van de der Lijn onderscheiding, 14 november 1986.—Meded.

Werkgr. Tert. Kwart. Geol., 23(4): 113-114, 1 fig.

Manuscript received 9 February 1988