All contributions in the current memorial volume are briefly commented upon, with the emphasis on how these issues touched upon, or were linked to, the long and productive professional careers of the late Felder brothers, in the fields of geology, palaeontology and human prehistory. Pertinent literature references are added, some of which are covered in the various papers, while others illustrate their wide range of interests and prolific publishing lives.

Uphill and drainage line environments reveal many hiatuses or discordances, because of truncation by erosion. In downslope position accumulation often prevailed outside the drainage lines and prevented erosion, even during unstable periods. Consequently, downslope sections yield the most detailed environmental data, but often lack contact with uphill series. However, for stratigraphical correlation the contact between downslope and uphill series is essential. In the Veldwezelt loess sequence this contact is intact, which provides additional data on transitional processes. In view of these special palaeoenvironmental conditions, exhibiting a transition between downslope and uphill areas and a south-east trending stream, an extraordinarily detailed Late Saalian, Eemian and Weichselian loess sequence could be reconstructed. The Veldwezelt series furnished important pedological, sedimentological, faunal, tephrochronological and cryogenic data, on the basis of which palaeoenvironmental conclusions could be drawn and six types of pedo-sedimentological cycles distinguished. A stratigraphical overview was obtained by correlating the Veldwezelt section with other west European loess frameworks and tephra sequences; the sedimentary series at Harmignies (Mons Basin, southern Belgium) and the Greenland GRIP ice core.

A new lyelliceratid, Lyelliceras escragnollensis sp. nov., is described from the condensed Albian of Escragnolles (Var) and La Balme de Rencurel (Isère), as well as from the upper Lower or lower Upper Albian of Maurepaire (Aube), in France. The new species is precisely dated on the basis of a previous record from the lower Middle Albian Lyelliceras lyelli Subzone of the Hoplites dentatus Zone at Courcelles (Aube). It is regarded as a short-lived descendant of Lyelliceras pseudolyelli, and is characterised as a compressed species of the genus in which the inner ventrolateral tubercles are weak and apparently absent on the early phragmocone whorls, the outer ventrolateral clavi feeble, offset to opposite across the venter, the siphonal clavi being more numerous than the outer ventrolateral.

New specimens described herein add to our knowledge of uncommon parataxa (embedment structures, borings and a certain type of burrow) from the type area of the Maastrichtian Stage, the material originating from the ENCI-HeidelbergCement Group (Maastricht), Ankerpoort-'t Rooth (Bemelen) and former Blom (Berg en Terblijt) quarries in southern Limburg (the Netherlands), and from the CBR-Romontbos (Eben Emael) and CPL SA (Haccourt) chalk pits in the province of Liège (northeast Belgium). Although Centrichnus eccentricus Bromley & Martinell has previously been recorded from this area, it has not received formal description; the specimen documented herein shares a test of the echinoid Echinocorys gr. conoidea with numerous other episkeletozoans. Podichnus cf. centrifugalis Bromley & Surlyk occurs both on echinocorythid echinoid tests and guards of belemnitellid coleoids; two out of seven specimens display radial discontinuous channels, indicative of the extreme penetration of filaments from the attached brachiopod's pedicle. Renichnus arcuatus Mayoral shows a range of morphologies, from the embedment structure sensu stricto through to specimens retaining internal moulds of the producing, embedded vermetid gastropod to free shells of Vermetus binkhorsti Cossmann. Burrows packed with bioclastic debris, particularly primary spines and a few test plates of phymosomatid echinoids, present a systematic conundrum, although appearing comparable to the ichnogenera Nummipera Hölder and Baronichnus Breton in several respects.

A complete growth series of Terebratulina chrysalis (Von Schlotheim, 1813) collected from its type area near Maastricht (the Netherlands) is described and illustrated, with fully adult and gerontic specimens included so as to increase current knowledge of this taxon. Most specimens collected from other European outcrops are juveniles which are similar to juveniles from the type area near Maastricht. However, adults collected from the latter area and those from lower Maastrichtian white chalk deposits in northern Europe are quite different. These differences can be explained by palaeoenvironmental conditions and taphonomic processes.

A palynological study of the Chalk Group (Campanian-Danian) in the Meer borehole (northern Belgium), which penetrated the thickest succession known in the Campine Basin, has revealed diverse, well-preserved organic-walled dinoflagellate cyst assemblages. The succession contains numerous chronostratigraphically significant dinocyst events, which are based mainly on the highest consistent occurrences of index species. At least 35 bio-events have enabled a subdivision into nine intervals, at stage or substage level, within the Campanian to Danian interval, as based on comparison with coeval assemblages elsewhere in northwest Europe, inclusive of stratotypes of stages and stage boundaries. Bio-events allow correlation of the section studied with the Campanian Exochosphaeridium? masureae, Areoligera coronata and Samlandia mayi zones, the Maastrichtian Pervosphaeridium tubuloaculeatum, Deflandrea galeata and Hystrichostrogylon coninckii zones, and the Danian Damassadinium californicum Zone. In addition, a correlation with other zonal schemes for the southern North Sea Basin and with conventional northwest European belemnite zones is presented. Comparisons with Boreal and Tethyan realms confirm that most bio-events may also be useful for interregional and global correlation. The Campanian-Danian dinocyst biostratigraphy of the Meer borehole is put alongside geophysical well logs and an ecozonation, in order to check the validity of lithostratigraphical correlations across the Campine Basin. This first, detailed correlation attempt shows that sensitivities to facies change associated with differences in accommodation space and sediment supply appear to be at the base of slight, yet consistent, shifts between the local lithological succession and the standard lithostratigraphical scheme of the Maastricht type area.

An overview is presented of belemnitellid faunas of Santonian to Maastrichtian (Late Cretaceous) age in the Mons Basin and in the Brabant-Méhaigne and Maastricht-Aachen-Liège areas (Belgium, southeast Netherlands). As many as twenty-two species of the genera Actinocamax Miller, 1823, Gonioteuthis Bayle, 1878, Belemnitella d'Orbigny, 1840 and Belemnella Nowak, 1913 have been recorded to date. On the basis of these, thirteen zones can be distinguished: three in the Santonian (G. w. westfalica, G. westfalicagranulata and G. granulata), six in the Campanian (G. granulataquadrata, G. quadrata, Blt. mucronata, Blt. woodi, Blt. minor I and Blt. minor II) and four in the Maastrichtian (Bln. obtusa, Bln. ex gr. sumensis/cimbrica, Blt. junior and Bln. kazimiroviensis). Correlative schemes between these zones and those proposed for Norfolk (southeast England) and for the combined Lägerdorf-Kronsmoor-Hemmoor section (northern Germany) are presented. The belemnitellid assemblage of the study area closely resembles that of Norfolk, but differs from the late Campanian faunas of northwest Germany.

In the type area of the Maastrichtian Stage (northeast Belgium, southeast Netherlands), two species of the rare hemiasterid echinoid genus Leymeriaster were known to date. Here we describe a third, L. campestris sp. nov., from the so-called ‘Laagje van Müller’ (Gemmenich Member, Vaals Formation) at Vaals-Eschberg, southern Limburg (the Netherlands), which is of early Campanian age. It differs from its late Maastrichtian congeners in the area, L. maestrichtensis and L. eluvialis, in that the pore pairs in the frontal groove of ambulacrum III are not in small depressions and the adjacent interambulacral margins are not thickened, raised and/or overhanging. It differs from L. maestrichtensis by the lack of a clear notch in the ambitus in ambulacrum III, and from L. eluvialis in the presence of a distinctly longer groove in ambulacrum III. Leymeriaster campestris sp. nov. is the first undoubted species of Campanian Leymeriaster known from northwest Europe.

An exhaustive screening of public collections containing remains of the latest Cretaceous (late Maastrichtian) marine turtle Allopleuron hofmanni (Gray, 1831) from the type area of the Maastrichtian Stage (southeast Netherlands, northeast Belgium) shows the available material to represent almost exclusively adult individuals. The various skeletal elements are not preserved in proportionally equal abundance, with portions of carapace, pectoral girdle, cranium and mandible overrepresented. These observations can be explained by population characteristics and taphonomic factors. During the late Maastrichtian, while hatchlings and juveniles in all likelihood lived and fed elsewhere, extensive seagrass meadows might have supported a population of only adult marine turtles.

Having been inspired by the leaflet, ‘Natuursteen in Maastricht. Aardrijkskunde in een oude stad’, written by P.J. Felder and published in 1977, we here present descriptions of the main types of natural stones applied in the city of Maastricht. A concise overview of the provenance area, mineralogy and physical properties of a selection of so-called historical building stones used in Maastricht, from Roman times onwards, is given. On a walk, starting at the Natuurhistorisch Museum Maastricht and ending at the Vrijthof, the main square of the city of Maastricht, details of building stones seen on the way are highlighted.

In southern Belgium (Mons Basin and Tournai region) and northern France (area between Lille, Valenciennes and Maubeuge), condensed sequences have been referred to as ‘tourtias’ since the start of the nineteenth century. These levels correspond to a succession of trangressive systems tracts and generally appear as dark green, glauconitic and microconglomeratic facies. They are distributed all along the base of the more important transgressive systems tracts of the Cenomanian and basal Turonian from the Boulonnais (northwest France) to the Mons Basin (southern Belgium), through the Artois and Douaisis. Their age can now be determined more accurately by identification of their ammonite content, as housed in museums such as the Institut royal des Sciences naturelles de Belgique (IRScNB, Brussels) and the Musée d'Histoire naturelle de Lille (MHNL). Here material from the IRScNB collections is described, illustrated and discussed; specimens contained in the MHNL collections were described in a previous paper.

The origin of a peculiar type of silicified limestone with nodular flints used in parish churches at Sluizen and Vreren, south of Tongeren (province of Limburg, Belgium), has now been elucidated by the discovery of the same rock type in its natural setting, namely the silicified top of the Cretaceous which underlies Clay-with-flints (‘flint eluvium’) and Oligocene sands in a disused quarry at Elst, municipality of Riemst (Limburg, Belgium). Co-operation between professional geologists and amateur palaeontologists has allowed to characterise this rock type, here referred to as ‘Elst tauw’, both petrographically and palaeontologically. The rich echinoid fauna has also been assessed, on the basis of a comparison with assemblages from the Clay-with-flints at Halembaye (Haccourt/Lixhe, province of Liège, Belgium) and at Zichen-Eben Emael in the Hesbaye region. P.J. Felder's ecozones, based on bioclast assemblages, substantiated by analyses of petrographical biofacies features of the original calcarenite, has allowed lithostratigraphic correlation of the ‘Elst tauw’ with the ‘Roosburg block’, which is a variety of ‘Maastricht stone’. Both methods indicate that the ‘Elst tauw’ developed in beds that can be assigned to the condensed Valkenburg-Schiepersberg interval of the lower Maastricht Formation. Petrographical analysis has shown the ‘Elst tauw’ to be quite distinctive; in addition, its natural occurrence at the Elst quarry matches the building stone records in rock type. The latter stem from the same small area, situated southwest of Maastricht. The major steps in its diagenetic history could be reconstructed, starting with pervasive pyritisation of the calcareous allochems, followed by silicification of the grains and pore spaces (different silica cements that became partially recrystallised), completed by oxidation of pyrite with transformation into limonite and, finally, dissolution of the non-pyritised or partially pyritised skeletal allochems creating a mouldic porosity. Silicification probably was achieved prior to the Oligocene. This particular mode of formation has generated a discussion on the proper use of the vernacular term ‘tauw’, a term used in a different sense by the industry, stratigraphers and students of building stones.

Belemnitellid cephalopods from the Maastrichtian stratotype area (southeast Netherlands) are shown to be comparatively well preserved. Although partial diagenetic alteration has been observed, micromilling techniques have permitted the extraction of pristine belemnite calcite, suitable for the reconstruction of strontium (Sr), oxygen (O) and carbon (C) isotope variation of Maastrichtian seawater. A distinct Sr isotope pattern in the Maastricht record can be matched stratigraphically with records from Hemmoor (northern Germany), El Kef (Tunisia) and ODP site 690 (Maud Rise, Antarctica), leading to a new chemostratigraphical age model for the Maastrichtian stratotype section. Our data improve currently applied strontium isotope stratigraphical reference curves by revealing an Sr isotope inflection pattern near the lower/upper Maastrichtian boundary that is a potentially diagnostic feature for intra-Maastrichtian stratigraphical correlation between distant sections. Belemnites further show significant stratigraphical oxygen isotope variation through the Maastrichtian. We interpret this variation to have resulted from palaeoceanographic reorganisations in the Atlantic Ocean during this time interval.