22 scientists from 10 countries (including Japan, Russia and the USA) met on September 13 at the Colegio Mayor Miguel de Unamuno of the Universidad del País Vasco, in Bilbao, Spain. This ‘university residence’ is a very comfortable student hostel, where all the participants except Marcos Lamolda (who preferred, understandably, to sleep at home) stayed throughout the meeting. The first evening during a most pleasant icebreaker party we exchanged news, looked at posters and enjoyed a wonderful assortment of tasty titbits and Spanish wines.

On Saturday, September 14, we travelled to Olazagutia. In the Cementos Portland quarry (Cantera de Margas) at Olazagutia (Navarra) two sides of the quarry were studied by the group, but more time was spent on the east side. M. Lamolda, J. Gallemi, G. Lopez, R. Martinez, J.M. Pons and C.R.C. Paul explained the results of their work on the quarry, below and above the level of the Coniacian/Santonian boundary. Among the macrofossils found while our group was studying the eastern side mainly echinoids and magnificent inoceramids should be mentioned. The condition of the outcrop was not ideal but the indications of the excursion leaders were thorough and the various levels were clearly marked.

After the visit to the Cementos Portland quarry the participants were presented a memorable lunch at the inn which the late Gundolf Ernst patronized during his pioneering geological work in the area.

On Sunday, September 15, we visited the Villamartin (Burgos) section situated on the northern part of the North Castilian Platform (El Paño Range) showing an intermediate position between basin and platform sequences. In the Villamartin section the Coniacian-Santonian boundary is situated in a part of the section with abundant macrofauna especially in the lower part of the section. J.M. Pons, J. Gallemi, G. Lopez and R. Martinez were the leaders of this excursion.

On Monday, September 16 we had scientific sessions: Jake Hancock gave an introductory lecture on ‘Some Coniacian-Santonian boundary sections in the USA’, explaining amongst other things why the Texan locality Ten Mile Creek near Dallas mentioned in Brussels (1995) as a possible candidate for the Coniacian-Santonian boundary is not completely satisfactory. We also had papers and posters on varied happenings (Foraminifera by Petrizzo, and by Premoli-Silva and Petrizzo; Nannofossils by Melinte and Lamolda; benthic Foraminifera by Peryt and Lamolda; bivalves by Dhondt; brachiopods by Gaspard) and on varied regions (the South Central Pyrenees by Gallemi et al.; the Seaford-Head exposures in England by Hampton et al.; the Mangyshlak Peninsula and the Peri-Caspian Basin (W. Kazakhstan) by Kopaevich and Beniamovskii; on comparative microfossil chronostratigraphy of the W. Interior and U.K. Chalk by Sikora et al.; Japan by Toshimitsu et al.; the Pueblo section (Colorado, USA) by Walaszczyk and Cobban) all around the Coniacian/ Santonian boundary. Finally, to remind us that geological history extends beyond the Santonian, Chris Paul gave a talk on stable isotopes at Zumaya.

The booklet containing the abstracts of the meeting and the excursion guides, also contains abstracts on the Coniacian-Santonian transition in the Urals (Amon), in the Basco-Cantabrian Basin (Gräfe), in Germany (Tröger), in Austria (Wagreich) and in the Russian Far-East (Yazykova and Zonova).

The last item on the scientific agenda concerned the suitability of Olazagutia as a possible boundary stratotype. Long discussions stressing positive and negative aspects of the quarry followed.

On the negative side the discussion mainly stressed the fact that the Olazagutia section is situated in a working quarry and that the ammonite fauna is poor. The first aspect means that its accessibility in the present circumstances is not fully guaranteed. The lack of ammonites means that correlation with other regions using macrofossils can best be based on inoceramids and echinoids.

On the positive side it was mentioned several times that the micropalaeontological data on the section are well studied including nannofossils, foraminifers (both planktonic and benthic), and that stable isotope dates exist. Also the inoceramid Cladoceramus undulatoplicatus occurs fairly commonly thus making it possibly to locate the Coniacian/ Santonian boundary fairly precisely.

It was proposed by several participants that other sections should be designated – or in case this is not possible according the ICS rules - to add a ‘para boundary stratotype’, for example at Villamartin. The alternative sections studied in the same area were shown to be either less useful because they are situated in sediments with poor microfauna or are less well studied.

The participants finally agreed that the Olazagutia section should be chosen among the three possible candidates for the Coniacian-Santonian boundary stratotype designated in Brussels (1995).

For the immediate future our Spanish colleagues agreed to prepare a very detailed description of the eastern side of the Olazagutia quarry as it is today and to publish this, possibly in Cretaceous Research. This description can also be used for submission first to the members of the WG and then to the voting members of the Cretaceous Subcommission, even if for this report to the Subcommission and to the ICS some aspects must be added (such as the comparison to other similar sections).

It was stressed and agreed upon that beyond the agreement with the present quarry owners a complete protection of the geological site should be obtained if possible by the authorities of the region (Navarra). According to the Spanish participants, laws existing in Spain make this possible.

A short speech of thanks to the local organiser and to all the participants for having taken such an active interest concluded the scientific part of the meeting.

The meeting was concluded by a very pleasant evening banquet.

It is hoped that the papers presented at the meeting will be published in a special volume of Cretaceous Research and Annie Dhondt has sent details about preparation of manuscripts to all participants who submitted abstracts.

Annie Dhondt

This report is a part of the Newsletter 5 of the Subcommission on Cretaceous Stratigraphy