 Dating the monuments remains difficult because of the movement of many from their original contexts prior to archaeological investigation . Most have been dated to the Early Preclassic period ( 1500 – 1000 BC ) with some to the Middle Preclassic ( 1000 – 400 BC ) period . The smallest weigh 6 tons , while the largest is variously estimated to weigh 40 to 50 tons , although it was abandoned and left unfinished close to the source of its stone . 
 Dating the monuments <a href='uninflect' title='1'><mark>remains</mark></a> difficult because of the movement of many from their original contexts prior to archaeological investigation . Most <a href='been_done' title='2'><mark>have</mark></a> been dated to the Early Preclassic period ( 1500 – 1000 BC ) with some to the Middle Preclassic ( 1000 – 400 BC ) period . The smallest weigh 6 tons , while the largest is variously estimated to weigh 40 to 50 tons , although it was abandoned and left unfinished close to the source of its stone . 
Dating da monuments remain difficult because of the movement of many from their original contexts prior to archaeological investigation . Most done been dated to the Early Preclassic period ( 1500 – 1000 BC ) w/ some to the Middle Preclassic ( 1000 – 400 BC ) period . Tdasmallest weigh 6 tons , while thdaargest is variously estimated to weigh 40 to 50 tons , although it was abandoned and left unfinished close to the source of its stone .