The Hesbaye Group is a stratigraphic group

Group (stratigraphy)

A group in stratigraphy is a lithostratigraphic unit, a part of the geologic record or rock column that consists of defined rock strata. Groups are divided into formations and are sometimes themselves grouped into "supergroups"....

 (a set of sedimentary layers) in the subsurface

Subsurface

Subsurface is the seventh studio album by British progressive metal band Threshold. The album was released in August 2004, and received an Album of the Month award in several European music magazines....

 of northeastern Belgium

Belgium

Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

. This group was deposited during the early Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 epoch

Epoch (geology)

An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

 and is subdivided into two formations: the Houthem Formation

Houthem Formation

The Houthem Formation, named after the Dutch town of Houthem, is a geological formation that crops out in the south of Belgian and Dutch Limburg. It has also been found in borings in the northeastern part of the Campine Basin...

 (lower) and the Opglabbeek Formation

Opglabbeek Formation

The Opglabbeek Formation is a geologic formation in the subsurface of the eastern part of Belgian Limburg. The formation consists of lagoonal and fluvial clay and sand and was deposited during the early Selandian...

 (upper). The group is named after the region of Hesbaye

Hesbaye

Hesbaye or Haspengouw , is a region spanning the south of the Belgian province of Limburg, the east of the Belgian provinces of Flemish Brabant and Walloon Brabant, and the northwestern part of the province of Liège.The Limburgish portion contains the cities of Tongeren, Sint-Truiden, Bilzen and...

 in the south of Limburg

Limburg (Belgium)

Limburg is the easternmost province of modern Flanders, which is one of the three main political and cultural sub-divisions of modern Belgium. It is located west of the river Meuse . It borders on the Dutch provinces of North Brabant and Limburg and the Belgian provinces of Liège, Flemish Brabant...

.

The Houthem Formation consists of shallow marine sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

y limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

s of early to middle Danian

Danian

The Danian is the oldest age or lowermost stage of the Paleocene epoch or series, the Paleogene period or system and the Cenozoic era or erathem. The beginning of the Danian age is at the Cretaceous-Tertiary extinction event...

 age (about 65-63 million years old). It is found in the province of Limburg

Limburg (Belgium)

Limburg is the easternmost province of modern Flanders, which is one of the three main political and cultural sub-divisions of modern Belgium. It is located west of the river Meuse . It borders on the Dutch provinces of North Brabant and Limburg and the Belgian provinces of Liège, Flemish Brabant...

 and the north of the province of Antwerp

Antwerp (province)

Antwerp is the northernmost province both of the Flemish Region, also called Flanders, and of Belgium. It borders on the Netherlands and the Belgian provinces of Limburg, Flemish Brabant and East Flanders. Its capital is Antwerp which comprises the Port of Antwerp...

. This formation also occurs in the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

, where it is considered part of the Chalk Group. The Opglabbeek Formation is an alternation of continental to lagunary clay, sand and lignite

Lignite

Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

 layers of early Selandian

Selandian

The Selandian is in the geologic timescale an age or stage in the Paleocene. It spans the time between and . It is preceded by the Danian and followed by the Thanetian. Sometimes the Paleocene is subdivided in subepochs, in which the Selandian forms the "Middle Paleocene".-Stratigraphic...

 age (about 60 million years old). This formation only occurs in the north and east of the province of Limburg. Corresponding deposits in the Netherlands are divided with the Landen Formation

Landen Formation

The Landen Formation is a lithostratigraphic unit in the subsurface of the Netherlands. This formation shares its name with the Belgian Landen Group, but the Belgian unit is thinner and has different definitions...

.

The Hebaye Group lies stratigraphically on top of older, Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 formations, such as the Maastricht Formation

Maastricht Formation

The Maastricht Formation , named after the city of Maastricht, the Netherlands, is a geological formation in the Netherlands and Belgium whose strata date back to the Late Cretaceous, within 500k years of the K-Pg boundary, dated to 65.5 million years ago. The formation is part of the Chalk Group...

 (sandy limestone). The late Paleocene Hannut Formation

Hannut Formation

The Hannut Formation is a geologic formation in the subsurface of northern Belgium. The formation consists of marine clay and silt, alternating with moer sandy layers. On top of this the lithology changes to limestone, siltstone and sandstone and the top of the formation is formed by a layer of...

(marine clays, sands and limestones) is normally lying stratigraphically on top of the Hesbaye Group .
(eds.); 2001: Paleogene and Neogene lithostratigraphic units (Belgium), Geologica Belgica 4(1-2), p. 135-152.