resistant rock mass behavior is the mica-poor nature of the rocks - by
definition best described as gneiss rather than schist."
|The rock is resistant
because Manhattan Schist is dense and hard. It varies between a
schist and a gneiss, in fact, this property has been known in NYC construction for over 150 years.
been reported by Merguerian to have more gneiss than schist.
(quotation will be provided)
|"The sampling and size of
specimens were not representative of the rock mass of Manhattan Schist,
and therefore did not conclusively prove that the rock is gneiss
convergent effects of unanticipated mineralogy and lithology, mylonitic
fabrics, and structure have resulted in a relatively anisotropic, tough
rock mass that has resisted excavation by mechanical means."
Contractor did not prove that it encountered a DSC since it did encounter
the same conditions that were described in the Contract Documents."