Uploaded by Nick Cutrupi


Mapping Assessment: Geological History
Nicholas Cutrupi
Nine Rocks were identified to make up the area investigated; two igneous, four sedimentary and three
metamorphic. Of the two igneous rocks, one was identified as granite due to its phaneritic and
porphyritic texture, light colour and pink tinge due to the presence of potassium feldspar. The other
igneous rock was identified as basalt due its black aphanitic texture with olivine phenocrysts present.
In order of ascending grain size, the four sedimentary rocks identified were; fossiliferous limestone,
mudstone, sandstone and conglomerate. Of these four sedimentary rocks three of them were
metamorphosed along their contact line with the granite, creating three non-foliated metamorphic rocks.
Contact metamorphosed limestone, mudstone and sandstone forms respectively; marble, hornfels and
The sedimentary rocks present would have been deposited first, as the granite is an intrusive pluton that
the basalt crosscuts. The fossiliferous limestone was the first to be deposited as it is part of the bedding
of the other two sedimentary rocks. It was deposited at an angle of forty-five degrees upon some
unknown bed. This angle of deposition affects all later deposits due to the nature of deposits to settle
equally. Next the mudstone was deposited; then the sandstone; then the conglomerate.
The Granite pluton would have then been formed, with the immense heat and slow cooling rate
metamorphosing the limestone, mudstone and sandstone that were in contact with it. After the intrusion
had cooled and metamorphosed its neighbour rocks, the basalt dyke formed and cut across both the
fossiliferous limestone and the granite intrusion. This dyke was at a temperature that well exceeded that
of its granite cousin, but no meaningful metamorphosing occurred due to its fast cooling rate, (being an
After the formation of these rocks, their surfaces underwent varied forms of uplifting, faulting,
weathering and erosion to produce the present topography; this being quite clear in the southern section
of the area where a sixty-degree fault occurred. The the north section of the fault is the hanging wall,
indicating that the fault plunges into the earth northward.