Department of Civil & Environmental Engineering CVNG 1011 Geology ASSIGNMENT Due

Question

Department of Civil & Environmental Engineering CVNG 1011 Geology ASSIGNMENT Due Date: Monday 23 March, 2018 before 12:30 pm The information you'll need for this lab is, for the most part, in the course notes and in the extra reading material posted on the course website but you will need to dig around for some more background information, and you will need to use some engineering judgement to answer some of the questions. Consider the following geologic and stratigraphic features. Sequence of Events: The diagram above shows several types of rock bodies, unconformities, and crosscutting relationships. The major rock bodies, faults, and unconformities are labelled by letters, each representing a significant geologic event. These are shown in alphabetical, not chronological order in the column below. Study the diagram and list these events in their proper chronological order. Briefly justify your choice. Say why it is in that order giving reasons etc. A Inclined sequence of sedimentary rockG Igneous intrusion of dolerite B Igneous intrusion of granite C Erosional surface H Volcanic cinder cone Alluvial fan JLava flow K Erosional surface intrusion of granite E Metamorphic rock s intrusion of dolerite L Horizontal

Explanation / Answer

Metamorphic rock, E, is a rock that is formed due to intense pressure of the overload or reworking of elements at high temperatures due to the intruding igneous bodies. Bed E has been intruded the most and at the bottom of all sequence, indiactes it to be the oldest. Bed E is faulted and exhibits a great bit of differential erosion on the left hand block of the region.

This Bed E is intruded by bed G as can be seen in the right block of the region, where the Dolerite intrudes and ends at the same time as bed E and does not continue into the overlying beds.

This is followed by a period of erosion, forming a layer of erosion K. Followed by a sequence of sedimentary rock , A. These beds were initially horizontal but were titled at the time of faulting of the Rock E.

The sequence A is then intruded by an igneoud intrusion of Granite. This was followed by a period of non deposition , forming the erosional surface, C which levelled the entire region, indicating a strong force of wind/water/glacier acting on the region for a prolonged time.

This, was followed by a horizontal sedimentary sequence, L. Which subsequently has been intruded by a sill or an igneous intrusion,B parallel to the bedding surface.

This region is then intruded by a massive igneous intrusion of dolerite on the left block, forming batholiths or umbrella shaped igneous bodies, which generally form at depths, indicating a large degree of erosion or fracturing above it.

Followed by a deposition of the alluvial fan, I. The extent of the alluvial fan, indicates a wide and powerful stream and the depth of the canyon indicates, high degrees of incision within the stream.

There are small Cinder Cones, which are volcanoes, H, breaking through the entire sequence and a group of volcanoes on the central region has led to the supply of a laval flow, J.

Thus the sequence goes like ( from youngest to oldest):

J - Lava Flow

H - Volcanic Cinder cone

I - Alluvial fan (the fan can be said to be younger than G, because of the contact at the topmost part of the diagram, where I conforms with the topology of the intrusion G.)

G - Igneous intrusion of dolerite

B - Igenous intrusion of Granite

L - Horizontal sedimentary sequence

C- Erosional surface

D - Igneoud intrusion of granite, which forms a sill into the sedimentary sequence A-.

A - Inclined sedimentary sequence

K - Erosional surface

F - Igneous intrusion of Dolerite

E - Metamorphic rock

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