( ( ( The ( Earth 's ) ) ( continental plates ) ) ( ( ( ( are ( ( an average ) ( ( 125 kilometers ) thick ) ) ) and ) ( were ( formed ( ( ( more ( ( than 3 ) billion ) ) years ) ago ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN Earth) (POS 's)) (JJ continental) (NNS plates)) (VP (VP (VBP are) (NP (NP (DT an) (NN average)) (ADJP (NP (CD 125) (NNS kilometers)) (JJ thick)))) (CC and) (VP (VBD were) (VP (VBN formed) (ADVP (NP (QP (JJR more) (IN than) (CD 3) (CD billion)) (NNS years)) (RB ago))))) (. .)))
The Earth's continental plates are an average 125 kilometers thick and were formed more than 3 billion years ago.
(ROOT (S (NP (NP (NP (DT The) (NN earth) (POS 's)) (JJ continental) (NN crust)) (, ,) (PP (IN on) (NP (NN average))) (, ,)) (VP (VBZ is) (ADJP (NP (CD 35) (NNS kilometers)) (JJ thick))) (. .)))