 Archaeological investigation of Olmec basalt workshops suggest that the colossal heads were first roughly shaped using direct percussion to chip away both large and small flakes of stone . The sculpture was then refined by retouching the surface using hammerstones , which were generally rounded cobbles that could be of the same basalt as the monument itself , although this was not always the case . Abrasives were found in association with workshops at San Lorenzo , indicating their use in the finishing of fine detail . Olmec colossal heads were fashioned as in @-@ the @-@ round monuments with varying levels of relief on the same work ; they tended to feature higher relief on the face and lower relief on the earspools and headdresses . Monument 20 at San Lorenzo is an extensively damaged throne with a figure emerging from a niche . Its sides were broken away and it was dragged to another location before being abandoned . It is possible that this damage was caused by the initial stages of re @-@ carving the monument into a colossal head but that the work was never completed . 
 Archaeological investigation of Olmec basalt workshops suggest that the colossal heads <a href='uninflect' title='1'><mark>were</mark></a> first roughly shaped using direct percussion to chip away both large and small flakes of stone . The sculpture was then refined by retouching the surface using hammerstones , which <a href='uninflect' title='2'><mark>were</mark></a> generally rounded cobbles <a href='null_relcl' title='3'><mark>that</mark></a>could be of the same basalt as the monument itself , although this <a href='negative_concord' title='4'><mark>was</mark></a> <a href='negative_concord' title='5'><mark>not</mark></a>always <a href='None' title='6'><mark>the</mark></a><a href='negative_concord' title='7'><mark>case</mark></a> . Abrasives <a href='uninflect' title='8'><mark>were</mark></a> found in association with workshops at San Lorenzo , indicating their use in the finishing of fine detail . Olmec colossal heads <a href='uninflect' title='9'><mark>were</mark></a> fashioned as in @-@ the @-@ round monuments with varying levels of relief on the same work ; they tended to feature higher relief on the face and lower relief on the earspools and headdresses . Monument 20 at San Lorenzo <a href='drop_aux' title='10'><mark>is</mark></a>an extensively damaged throne with a figure emerging from a niche . Its sides <a href='uninflect' title='11'><mark>were</mark></a> broken away and it was dragged to another location before being abandoned . It is possible that this damage was caused by the initial stages of re @-@ carving the monument into a colossal head but that the work was never completed . 
Archaeological investigation of Olmec basalt workshops suggest dat the colossal heads was first roughly shaped usin direct percussion to chip away both bigass and small flakes of stone . The sculpture was then refined by retouching da surface uusinhammerstones , which was generally rounded cobbles could be of the same basalt as the monument itself , although this ain't always no case . Abrasives was found in association with workshops at San Lorenzo , indicating their use in tdafinishing of fine detail . Olmec colossal heads was fashioned as in @-@ thda-@ round monuments with varying levels of relief on thedame work ; they tended to feature higher relief on the dae and lower relief on the earspools and headdresses . Monument 20 at San Lorenzo an extensively damaged throne with a figure emerging from a niche . Its sides was broken away and it was dragged to another location b4 being abandoned . It is possible that this damage was caused by the initial stages of re @-@ carving the monument into a colossal head but tdatthe work was never completed .