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IimeslOne conglomerate have been found.
131
] 4 3 facics I H2- Thick- IQ Very Thick.bedded Sandstone
Facies LH2 is dominated by thick- 10 very thick-bedded. massive. medium- to
coarse-grained sandslone (plate 3.17). Particularly in the Bay of Islands area. beds may
be as gceal as 10 m thick, although it is unclear as 10 whether some of these beds may
be amalgamated. Bases of the beds are commonly non-erosive and lopS lend (0 be friable
and poorly defined. suggesting a poorly developed normal distribution grading. The only
sU"uctures commonly displayed by the saooslone are a variety of fluid escape suuclures
and concretions. The fluid escape structures are cemented by calcite and are resistant
10 weathering. Concretions occur as spherical features in which calcite cementation has
nucleated around shale chips (cannonball concretions), and in continuous rinds or layers
up 10 10 cm thick which may refleci bedding parallel variations in the mud/sand ratio
wilhin Ihe bed. which are otllcrwise invisible to the !\aXed eye. Some beds display a
crude parallel stratification defined by coarser and finer layers of saoo which may show
inverse· normal grading within the layers.
The bases of the beds may contain large
!lutes (20 cm wide) or grooves. and horizonlal feeding trace fossils are present on the
bases of a few beds. Botsford ([988) has identified a suite of trace fossils in the Lower
Head Formaliondominatedby~and~, which he considered 10
be Iypical of the low diversity ~ ichnofacies, and which moreover aTe
characteriSIK: of a 'l1ysch related assemblage'. Facies LH2 QndStOrlt beds are laterally
continuous wilhin the scate of the available outcrop. but may be amalgamated; however,