Geological History of Kelburnia: A Research Study

The report explains the geological history of various events that occurred in the landmass of Kelburnia. It details the formation of clasts due to mechanical weathering and their interaction with ground water or explosive exsolution emplaced with igneous bodies. The sandstones were formed by cemented grains joined through silica, clay, and calcite, accumulated from water streams and then compacted by increased pressure and mineral precipitation. The Paleogene marine clam fossils were deposited on sedimentary rocks after being burrowed in mud or deep water as well as on sea shores.

ESSAY PROJECT GEOLOGY

TABLE OF CONTENTS
INTRODUCTION...........................................................................................................................1
PRINCIPLES OF GEOLOGY.........................................................................................................1
GEOLOGICAL HISTORY OF KELBURNIA...............................................................................1
Metamorphic, granite and conglomerate rocks origin............................................................1
Origin of coal and Cretaceous leaf fossil in Kelburnia..........................................................2
Evolution of fossil rich segments in Kelburnia......................................................................3
Origin of Devonian trilobite and neogene marine snail fossil................................................3
Evolution of Tephra volcanic ash, Basalt intrusion and Breccia in Kelburnia......................4
Presence of sandstone and Paleogene marine clam fossil......................................................4
CONCLUSION................................................................................................................................5
REFERENCES................................................................................................................................6

INTRODUCTION
The geological history is an important area of interest for geologists. Geologists are
known to use various principles in order to find the sequence and origin of occurrence of events
(Harris, 2014). The report will explain the sequence and origination details of geological events
which occurred in the hypothetical landmass called Kelburnia. The report will use various
principles to determine the age and sequence of rocks and for identification of events.
PRINCIPLES OF GEOLOGY
For analysing the geological history of events at Kelburnia, the following principles are
used:
Original horizontality principle: According to this principle, sediments are deposited as
horizontal beds. The same principle is demonstrated in deposition of non-marine and marine
sediments as well.
Superposition principles: As per this principle, the sedimentary rocks can be considered as
vertical time line in which the layers below it is considered as older to it and the layers above it
are considered as younger than it.
Principle of Faunal succession: This principle states that the appearance and the structure of
fossils within sedimentary rocks can be used as the criterion to predict the age of the geological
component in which fossil is present (Richardson and et.al., 2015).
GEOLOGICAL HISTORY OF KELBURNIA
The geological sequence of the events in Kelburnia landmass occur in the following
sequence. The history of their occurrence is based on the principles of geology.
Metamorphic, granite and conglomerate rocks origin
Granite is an igneous rock and has a granular texture. The occurrence of Granite in
Kelburnia was caused when liquid rocks known as magma were pushed upwards from the
interior of the earth. This is the reason they are considered as the oldest rocks of Kelburnia.
When magma is pushed upwards then it undergoes into intrusion process which is followed by
cooling and hardening. When magma cools down then, it again undergoes a process called
fractional crystallization. This process enhances the constituent elements of Granite such as
1

silica, potassium and aluminium by lowering the content of elements like iron, calcium, and
other salts.
In Kelburnia region, evolution of Metamorphic rocks occurs via contact metamorphism
mechanism. With this approach, magma heat intrudes through Granite heat that causes
metamorphism (Reynolds and et.al., 2016). Contrary to the Granite rocks which were formed
earlier in Kelburnia and did not undergo into crystallization process from silicate.
Kelburnia region observed the formation of Conglomerate rocks after the evolution of
Metamorphic and Granite rocks. These rocks do not contain any kind of fossils. These rocks are
formed when boulders or gravels are subjected to the wave action and as a result, these are
transported to a region which is far from their source (Wood and plants, 2018). The existence of
conglomerate rocks in Kelburnia land mass indicated that the region was once occupied with
glaciers or had experienced water flow region.
Origin of coal and Cretaceous leaf fossil in Kelburnia
After many years of the formation of conglomerate rocks, the organic materials including
dense forests were buried in the swamps or underneath soil. These piles of organic materials
transformed into peat and different forms of coal, under the influence of excessive pressure and
heat.
When organic material was buried in Kelburnia, then gradually with time and soil
deposition, temperature was increased and deposition got compressed. The presence of mud
prevented the biodegradation of plant matter. Thus, dead vegetation is transformed into coal in
Kelburnia. Cretaceous leaf fossils are abundant in the sedimentary rocks. These fossils were
formed when vegetation was settled in finely grained sea bed (Adams, MacKenzie and Guilford,
2017). The accumulation of mud, silts and soil deposition helped these traces to accumulate as
fossil.
Evolution of fossil rich segments in Kelburnia
Limestone formation is the first evolution in fossil rich segment of Kelburnia. The major
proportion of the limestone is made up of calcium carbonate. The formation of conglomerate
rocks depict that this region has water flow. Thus, various types of marine organisms participated
in precipitation of calcium carbonate from the water flow to develop a protective shell called
exoskeleton. The sediments of shells undergo into process of compaction and cementing. It
2

causes crystallisation and hardening of rocks. Limestone is the most common source of fossils.
This sedimentary rock in Kelburnia is formed either by precipitation of calcium carbonate or by
the accumulation of shell, algal and corals.
After the evolution of lime stone, another fossil containing rock called mudstone was
evolved in Kelburnia. Mudstone is a sedimentary rock which is composed of mud and is finely
grained. When the pressure is raised over time period then finely grained clay or mud particles
gets aligned with each other and result in fissility. This structure which consists of thin layers is
called shale and has different characteristics as compared to mudstone (Seibold and Berger,
2017).
The mudstone does not comprise of layers because its layers are disrupted by the
burrowing fossils in sediments before lithification process. Some traces of mudstone in
Kelburnia region are also observed and as a result of this process, formation of compacting of
buried mud due to overlying sediments. And when water is squeezed out by natural processes,
the resultant component is obtained in the form of mudstone.
Most of the mudstones are finely grained but despite this, almost 70% of their structure is
composed of sedimentary rocks source (Wood and plants, 2018). These sediments which have
excellent level of fineness the fossil imprints are easily developed. The mudstones contain
organisms which were died or fell into the mud.
Origin of Devonian trilobite and neogene marine snail fossil
Devonian trilobite fossils belong to marine arthropods. Their presence in Kelburnia
provide significant proof that the region was flourished to a great extent in early Cambrian
period. The region may have a presence of sulphur dependent bacteria in the regions which was
the primary food source for trilobite.
The geological history of Neogene marine snail fossil in Kelburnia indicates that the
region was rich in marine diversity. With the water streams or high tides, the snail shells were
buried deep below soils and with the evolution of rocks and temperature variations, these marine
fossils were formed. Neogene marine fossils have very close similarity with the terrestrial fossils
(Seibold and Berger, 2017).
3

Evolution of Tephra volcanic ash, Basalt intrusion and Breccia in Kelburnia
The rock fragments which are ejected from volcano eruptions is known as Tephra. This
volcanic ash consists of minerals, volcanic glasses and pulverized rocks. The origin of this
volcanic ash in Kelburnia is formed when magma gases were expanded and violently escaped
into the atmosphere. In this process, magma was shattered and it undergoes into solidification of
rocks in atmosphere. There may be a possibility that in Kelburnia an interaction of water with
magma has caused shattering of magma.
After the evolution of volcanic ash, Basalt intrusions were evolved in the landmass.
Basalt are finely grained rocks. They usually develop in underground regions and below the
nucleation conditions, which are favourable after the volcanic eruptions (Delpueyo Español and
et.al., 2016). The geological origin of Basalt intrusion occurs in the situations when magma
intrudes with deep situated rocks or in comparatively low temperature. The magma temperature
is around 1100 degrees Celsius while intruding surface or rocks that are 20 and 100 degrees
Celsius respectively. Thus, it can be concluded that Basalt intrusions are formed due to
crystallisation of molten magma which is also affected by density gradient between magma and
local rocks.
Kelburnia also has traces of Breccia rocks. These rocks consist of angular fragments and
the composition of these fragments may be same or different. These clasts are formed due to
mechanical weathering and allows minimum transport. These rocks were formed in Kelburnia
when magma interacted with ground water and this interaction resulted in explosion. It is also
possible that they were formed when explosive exsolution emplaced with igneous bodies. The
exsolution was generated by volatile phases or interaction of magma (Wang and et.al., 2017).
Presence of sandstone and Paleogene marine clam fossil
The sandstones are formed in Kelburnia by cemented grains which are joined through
silica, clay and calcite. The sand layers are accumulated due to water streams and then these
layers are cemented and compacted by increased pressure and precipitation of the minerals
which occurs within pores of sand grains.
Sandstones are the most common source for the origin of Paleogene marine clam fossil.
These marine fossils have different characteristics as they are of same age of the terrestrial
fossils. Paleogene marine calm are the animal related fossils and do not contain traces of plant
4

bodies. These fossils consist of animal shells which were burrowed in mud or deep water as well
as on sea shores. With time, these shells or fossils were deposited on sedimentary rocks (Van
Roy, Briggs, and Gaines, 2015).
CONCLUSION
The report had explained the geological history of various geological events which
occurred in landmass of Kelburnia. Thus, it can be concluded from the report that the region of
Kelburnia has rich and significant history of geographical events which must be analysed for
research study.
5

REFERENCES
Books and Journals
Adams, A.E., MacKenzie, W.S. and Guilford, C., 2017. Atlas of sedimentary rocks under the
microscope. Routledge.
Delpueyo Español, X., Vilaseca Ricart, M., and et.al., 2016. Multispectral and colour imaging
systems for the detection of small vertebrate fossils: A preliminary study. Palaeontologia
electronica. 19(3). pp.1-9.
Harris, E.C., 2014. Principles of archaeological stratigraphy. Elsevier.
Reynolds, S.J., Johnson, J.K., and et.al., 2016. Exploring geology. McGraw-Hill Education.
Richardson, N.J., Richards, F.L., and et.al., 2015. Industrial structural geology: principles,
techniques and integration: an introduction. Geological Society, London, Special
Publications. 421. pp. SP421-15.
Seibold, E. and Berger, W., 2017. The sea floor: an introduction to marine geology. Springer.
Van Roy, P., Briggs, D.E. and Gaines, R.R., 2015. The Fezouata fossils of Morocco; an
extraordinary record of marine life in the Early Ordovician. Journal of the Geological
Society. 172(5). pp.541-549.
Wang, Y., He, H., and et.al.,2017. Origin of Permian OIB-like basalts in NW Thailand and
implication on the Paleotethyan Ocean. Lithos. 274. pp.93-105.
Online
Wood and plants. 2018. [Online]. Available through:
<https://jurassiccoast.org/fossilfinder/focus-on-fossils/wood-and-plants/>
6

7