The Upper-Maastrichtian Formation of Maastricht (if fully exposed) consists of 6 chalk members, each one separated from the latter by a horizon. In every horizon vertebrate remains can be found, some are better than others. The presence and/or thickness of those horizons are very different from quarry to quarry. Sometimes gorgeous specimens can be found in situ in the surrounding chalk members itself.
At the base of the Valkenburg Chalk and on top of the Lanaye Chalk (top of the underlying Gulpen Formation), the Lichtenberg Horizon can be observed: a small layer, very much varying in thickness (forming lenses), where shark teeth can be locally more abundant (see picture below). This horizon, best exposed in the ENCI quarry near Maastricht (Netherlands), gives the best view on the inhabitants of the sea at the end of the Cretaceous period. A profile of the ENCI quarry (after Felder & Bosch) can be found on the website of the Dutch Geological Society NGV. In other quarries this horizon is not so well exposed.
The Valkenburg Chalk is covered by the Gronsveld Chalk (with the Horizon of St. Pieter at the bottom), followed by the Schiepersberg Chalk (with the Horizon of Schiepersberg at its base).
The Emael Chalk starts with the Romontbos Horizon, again usually a small horizon, but rarely forming lenses bearing lots of vertebrate remains. Sometimes the Lava Horizon is also exposed, half way the Emael Chalk member (Marnebel quarry, Eben-Emael). Also this horizon can be locally thicker and yielding nice specimens. The Emael Chalk comes to an end with the Horizon of Laumont.
The last two chalk members, the Nekum chalk and the Meerssen chalk, are highly fossiliferous. Sedimentation took place in shallow water in a tropical climate (Felder & Bosch, 2000).
Palaeogaleus and Centrophoroides are among the most common
species. With the exception of Pseudocorax and maybe Palaeohypotodus,
generally larger teeth are scarce. Squalicorax pristodontus is present;
Synechodus, Protolamna and Anomotodon are only
Other fossils present are Mosasaur remains (teeth and vertebra), sea urchins (huge Hemipneustes...more than 25 species in the Nekum chalk!), different brachiopods and belemnites, the lobster Protocallianassa faujasi (Desmarest, 1822) and many other.