H.M. Leach’s scientific contributions

... Island, French Polynesia and New Zealand), a wider variety of adze types were made , resulting in even more distinctive reduction sequences . Preform replication studies have also been applied to explore reduction sequences and to identify techniques used during adze manufacture Leach and Witter 1987;. Another common aspect of core analysis is determining why blanks and preforms were rejected. ...

Reference:

Polynesian quarrying and adze production in southern New Zealand: Social organisation and manufacturing technology

... The three quarries recorded in the greater complex exhibited scree and talus material, collected or excavated from subsurface deposits or flaked to produce blanks. Tataga-matau preforms were trapezoidal and triangular cross-sectioned types predominantly produced on flake blanks (Leach & Witter, 1990). Radiocarbon dates indicate that small-scale adze manufacture took place at Tataga-matau as early as the eleventh century AD, with organised intensive adze production during the 14th and 16th centuries (Leach, 1993). ...

Reference:

An archaeological review of Polynesian adze quarries and sources