The discovery of a colossal head at Tres Zapotes in the nineteenth century spurred the first archaeological investigations of Olmec culture by Matthew Stirling in 1938. Seventeen confirmed examples are known from four sites within the Olmec heartland on the Gulf Coast of Mexico.lthough most of the facial detail is lost, the crinkling of the bridge of the nose is still evident, a feature that is common to the frowning expressions of the other Olmec colossal heads. La Venta Monument 4 measures 2.26 metres (7.4 ft) high by 1.98 metres (6.5 ft) wide and 1.86 metres (6.1 ft) deep.