84 



A.B. SMITH ETAL. 



Lighthouse at 

 Cabo Mayor 



Fig. 2. Map showing the location of the main echinoid-bearing horizons in the Santander region. Cantabria, studied in this paper. 



There then follows a thick succession of bedded sandy limestones, 

 with thin calcarenitic limestones, and evidence of surge channels and 

 tempestites (Wilmsen et al., 1996), indicative of deposition within 

 normal wave -base. This part of the succession was deposited under 

 rising sea-level. There are a few thin conglomerates and shell-rich 

 calcarenites which probably represent storm debris flows from near- 

 shore habitats. 



The upper beds become unfossiliferous, and return to a series of 

 thinner bedded calcarenites and sandy limestones with abundant 

 hiatuses and hardgrounds; they are dolomitized and were presum- 

 ably emergent. Consequently, the boundary between the 

 Maastrichtian and Palaeocene cannot be determined on faunal 

 grounds. The dolomites are microcrystalline, or occasionally pseudo- 

 oolithic, with sparse gastropods and ostracods seen in cross-section, 

 and are succeeded by a thin succession of calcarenites full of 

 hardgrounds and sedimentary hiatuses. Above, there are thicker- 

 bedded calcarenites with abundant asteroid ossicles, sandy in some 

 levels, and with abundant Rhodoficiae algae and Microcodium at the 

 base. These dolomites and calcarenites together form the San Juan 

 Formation, and have been attributed to the Danian and Montian. The 

 succession is capped by a very thin series of calcarenites with 

 glauconite, the Sancibrian Formation, which has a Thanetian 

 microfauna (Heredia et al., 1990). 



In terms of depositional environment, the Cabo de Lata Formation 

 represents relatively shallow inner platform elastics deposited within 

 fair-weather wavebase (Heredia et al., 1990). The presence of 

 echinoids in these beds was first noted by Jimenez de Cisneros 

 (1910) and Mengaud (1910), who correctly attributed these beds to 

 the Maastrichtian. Jimenez de Cisneros (1912) listed the following 

 echinoid species as coming from Santander: Echinoconus conicus 

 Breynius [=Galerites albogalerus Klein], Echinocorys vulgaris 

 Breynius, E. conicus Breynius, Hemipneustes pyrenaicus Hebert, 

 Hemiaster prunella Desor and Cidaris cf. C. subvesiculosa 

 d'Orbigny. Later, Lambert (1920-22) identified five echinoids from 



the Maastrichtian of this area; Tylocidaris ramondi Leymerie, Conulus 

 gigas Cotteau, Clypeolampas leskei Goldfuss, Hemipneustes 

 pyrenaicus Hebert and Echinocorys tercensis Lambert. Wilmsen et 

 al. (1996) noted the presence of several echinoid events and listed a 

 number of genera and species. 



The San Juan Formation is interpreted as being deposited in a 

 shallow, restricted internal platform setting, which becomes pro- 

 gressively less restricted upwards into the Sancibrian Formation. 



Echinoids have been collected from 9 levels at ten localities along 

 the cliff section west of Santander (Figs 2, 3). 



The Basque region 



Only deep-water Maastrichtian-Palaeocene facies are represented 

 in the Basque region. During the early Maastrichtian continental 

 slope turbidites were deposited. However, near the end of the early 

 Maastrichtian there was a marked reduction in siliciclastic input, 

 probably marking the world-wide late Maastrichtian regression. 

 Following the K-T boundary there was an even more dramatic 

 reduction in siliciclastic input to the basin, resulting in the deposition 

 of pink coccolith limestones (commonly resedimented) during the 

 Danian (Ward & Kennedy, 1993). Hiatuses and non-depositional 

 surfaces are common in these Danian beds reflecting a major rise in 

 sea-level. 



From their study of coastal stratigraphical sections of the Zumaya- 

 Algorri Formation at Sopelana, Zumaia, Hendaye and Bidart, Ward 

 & Kennedy ( 1 993) recognised five Maastrichtian units, referred to as 

 Members I-V. Echinoids are found throughout the section "but never 

 in great abundance, and only rarely in bedding plane concentrations' 

 (Ward & Kennedy, 1993). They are most common in Members IV 

 and V. We have plotted the stratigraphic occurrence of echinoids 

 from these localities onto a single standard section. Ward & Kennedy's 

 (1993) Zumaia lithological section (Fig. 4). 



The echinoid fauna from this region has not been studied since the 



J 



