The assemblage types are defined as follows (see also Figure 1):
Long blade assemblages. Terminal Upper Palaeolithic assemblages, characterised by the presence of long and giant blades, opposed platform technology, use of a soft stone hammer, platform faceting, the presence of bruised blades and a variety of different microlith types (obliquely blunted points, often with a pronounced concave truncation, trapezes, Blanchère or Ahrensburgian points) (Barton 1989; 1991; 1998).
Star Carr-type assemblages. Defined by the presence of simple obliquely blunted points, large isosceles and scalene triangles and trapezes (Radley and Mellars 1964; Reynier 2005).
Deepcar-type assemblages. Characterised by the presence of slender obliquely blunted points and partially backed points, often with retouch on the leading edge, and usually lateralised to the left (>70%). Also present at lower frequencies are rhomboids and triangles (Radley and Mellars 1964; Reynier 2005).
Basally modified assemblages, including Horsham-type and Honey Hill-type assemblages. This is defined by the presence of microliths with basal modification taking a variety of different forms, ranging from simple basal truncations to asymmetric concave truncation (Horsham points) or invasive inverse flaking (Honey Hill types). These are accompanied mainly by small obliquely blunted points, isosceles triangles and rhomboids, though a range of other types can also be present. Microliths in Horsham and Honey Hill assemblages are strongly lateralised to the left (95%). The rationale for subsuming two previously identified Mesolithic types, Horsham (Clark 1934) and Honey Hill (Saville 1981), into a single category is partly because of the small number of radiocarbon dates associated with these types, but also because there exists a range of microlithic assemblages that contain basally modified points that do not fit within these tightly defined groups. These include sites beyond the classic geographical range of Horsham and Honey Hill types, such as at Mother Grundy's Parlour, Derbyshire, and Cramond in Edinburgh. Though this larger category encompasses considerable variation, so too do the Star Carr and Deepcar groups. The presence of basally modified points is taken as a chronological marker elsewhere in Europe, indicating the appearance of middle Mesolithic assemblages.
Small scalene triangle assemblages. Defined by the presence of small scalene triangles (usually backed on two edge only during the earliest part of the late Mesolithic) and narrow backed bladelets. Small obliquely blunted points are also occasionally present at the start of the period. This group has traditionally heralded the appearance of the late Mesolithic, though it is worth noting that small scalene triangles are also present in some basally modified assemblages, such as Longmoor I.
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