But at the same time, there is a lot of instability below the surface, where different age groups are grinding against one another like shifting tectonic plates.

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Engineers have now said it cannot carry traffic due to the "potential instability of the road surface".

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She told him (and the rabbits that sometimes surreptitiously accompanied the riders) that people were becoming more and more unbalanced: studies had proved it, which led the psychiatrist to conjecture that perhaps mental instability was not so much a disease as a stratum of normality, just below the surface of normality as it was commonly conceived.

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