10: at location y the boundary between the red sand- stone and the black shale marks the

(1) beginning of the cenozoic era
(2) beginning of the mesozoic era
(3) end of the cenozoic era
(4) end of the mesozoic era

11: an unconformity can be observed at location z which rock layer was most probably removed by erosion during the time represented by the uncon- formity?

(1) conglomerate
(3) black shale
(2) gray siltstone
(4) brown siltstone

12 the fossils in the rock formations at location xindi- cate that this area often was covered by

(1) tropical rain forests (2) glacial ice
(3)desert sand
(4) seawater

13 which rock layer was formed by the compaction and cementation of particles that were all less than 0.0004 centimeter in diameter?

(1) red sandstone
(3) brown siltstone
(2) green shale
(4) conglomerate