( ( On ( the ( human ( time scale ) ) ) ) ( , ( caves ( ( are ( a ( nonrenewable resource ) ) ) . ) ) ) )
(ROOT (S (PP (IN On) (NP (DT the) (JJ human) (NN time) (NN scale))) (, ,) (NP (NNS caves)) (VP (VBP are) (NP (DT a) (JJ nonrenewable) (NN resource))) (. .)))
On the human time scale, caves are a nonrenewable resource.
(ROOT (S (NP (NP (NNP Soil)) (, ,) (PP (IN for) (NP (JJ human) (NNS purposes))) (, ,)) (VP (VBZ is) (S (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-)) (VP (VB nonrenewable) (NP (NN resource))))) (. .)))