Course:EOSC311/2020/Linking the Interior and Exterior: Earth and It’s Human Inhabitants

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Psychology and Geology are two disciplines in which understanding the bigger picture is both useful and necessary. In order to do so, one must examine subjects as a whole, looking at both the interior and the exterior. In the case of psychology, this would entail observing both the internal processes of the mind, as well as the exterior behaviours that are observable. For geology and the study of the Earth as a whole, this involves observing the internal processes such as convection currents, that stimulate external processes such as earthquakes, plate movements, and hotspots. Gaining a comprehensive understanding of the subject of study goes both ways as they are interconnected and part of a complete system. Observing the interior can aid in understanding external process, and observing external processes can also aid in understanding the internal processes that are occurring.

Psychology involves studying both the mind and the body, as well as behaviours that may be observed. By examining various signs and symptoms that people portray, psychologists are able to gain an understanding behind the internal processes that are occurring and driving specific behaviours. Studying behaviours, symptoms, and thought processes is particularly important to psychology as it allows for the ability to diagnose disorders or disabilities, such as mental disabilities or anxiety disorders.

Geology, or the study of the Earth as a whole, may look at the exterior features of the Earth such as rocks, volcanoes, or mountain ranges, in order to understand the processes that occurred internally to allow for such features to be constructed. Or one may turn to the interior workings of the Earth to understand the processes that stimulate the construction of the observable features on the surface of Earth. In either sense, they are interconnected and thus must be viewed as one system with many different connections and systems at work.

Throughout this page, the relation between the psychological phenomena of Obsessive Compulsive Disorder, as well as Savant Syndrome, will be compared with geological processes such as hotspots, earthquakes, and plate tectonics. The interior and exterior processes of each will be discussed in order to provide a thorough understanding of both subjects and how they may be related.

The Relations Between Geology and Psychology

Overview of Earth's internal and external layers

The study of geology is a science that examines Earth’s structure as well as it’s processes. Geology looks at the internal processes that maintain the Earth, as well as the external features that result from these internal workings. By examining the external features of the Earth, such as rocks and other physical features, geologists are able to discern information about the happenings of the interior of the Earth. The notion of viewing both the interior and the exterior as a whole, in order to understand the entire system, is also evident in another field of study, namely psychology. Psychology is the study of both the human mind and human behaviour. Similar to geology, psychology analyzes the interior, the mind or brain, as well as the exterior, the behaviour that is exhibited, in order to understand humans in the broader perspective.

The Earth, as well as the human brain, function in similar regards as they both depend on various cycles and systems. The Earth is fueled by systems such as the carbon cycle, the water cycle, and convection currents. Similarly, the human body is fueled by systems such as the central nervous system and the glucose system, with the latter being the primary system that fuels the human brain.

Connections of the human brain

The study of psychology encompasses various psychological disorders, such as anxiety disorders or developmental disorders. Psychological disorders often entail the mind functioning in unusual ways, which often results in a subsequent outward display of behaviours that may be considered unusual. Studying the inner workings of the mind and it’s systems, such as the central nervous system that controls most functioning of the spinal cord and brain, can help us to better understand the outward presentation of behaviours that are evident. In a similar regard, but from a geological aspect, we can look at internal proceedings of the Earth, such as hot spots, and view the outward presentation on the exterior of the Earth in the form of islands that have been created by such hot spots.

The relation examined throughout, specifically the relation between geology and psychology, was notable as it was particularly interesting to observe that both disciplines may gain knowledge about their respective subjects of study by focusing on the internal and external functions, in order to build an overarching and comprehensive view of their respective subjects of study, pointedly, the Earth and humans.

Linking the Interior and the Exterior

Psychological Perspectives

Obsessive Compulsive Disorder (OCD)

Obsessive compulsive disorder cycle - negative feedback loop

Obsessive Compulsive Disorder, otherwise known as OCD, is a psychological disorder. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), OCD may be classified further as an anxiety disorder. The disorder manifests in the form of repeated behaviours, otherwise known as compulsions, as well as repetitive thoughts, known as obsessions.[1] Individuals who suffer from OCD do not have control over their compulsions and obsessions and suffer from anxiety as a result.

The causes of OCD are a combination of neurological, genetic, behavioural, cognitive, and environmental factors that trigger the disorder.[2] The repetitive behaviours or compulsions that an individual who suffers from OCD engages in are the external manifestations of the disorder. Whereas the repetitive thoughts or obsessions that a person experiences are the internal manifestations of the disorder.

OCD may be associated with an uncommon mutation of the human serotonin transporter gene.[2] Serotonin is a chemical within the human body that contributes to the overall wellbeing and happiness of an individual and if this chemical is low internally, the decreased levels can lead to anxiety, as is the case with OCD.

The compulsions that an individual with OCD experiences are learned responses that help an individual reduce or prevent anxiety or discomfort associated with obsessions and urges.[2] The learned responses are behaviours, or external functions, that when completed, cause an internal response in the form of decreased anxiety or discomfort. The learned responses are therefore part of a negative feedback loop in which behavioural conditioning is contributing to the development and maintenance of obsessions and compulsions.[2] The individual who suffers from OCD understands that by performing the repetitive behaviour, the external act, then the internal component, the obsessions and anxiety, will diminish or disappear.

OCD is a psychological disorder that is similar in some aspects to the geological phenomenon of hotspots in terms of internal features influencing external features or expressions. Hotspots occur at areas in which mantle plumes cause magma to rise to the surface of the Earth.[3] The process of where hotspots occur and the external impact that they have on the Earth, such as island formation, cannot be controlled. In a similar regard, individuals with OCD cannot control when their compulsions and obsessions will arise and in a sense these compulsions rise to the surface and are released as an external expression of various repetitive or obsessive behaviours.

Savant Syndrome

Examples of superior skills possessed by Savants

Savant Syndrome is a particularly rare condition in which persons with developmental disabilities, including but not limited to autism, or other central nervous system disorders or disease have some spectacular ‘island of genius’ that stand in stark contrast to the individual’s overall limitations.[4] The condition may be one that is present at birth, known as congenital Savant Syndrome, or one that develops later on in life following a central nervous system injury or disease, known as acquired Savant Syndrome.[4]

The ‘island of genius’ or specific skill sets that are prominent in individuals with Savant Syndrome fall into five general areas, those being music, art, calendar calculating – the ability to name the date or day of the week when given a date ranging from decades to millennia with little to no effort, mathematics, or mechanical/visual-spatial skills.[4] Regardless of which skill set the individual with Savant Syndrome presents with, the skill is associated with superior ability in habit- or procedural-type memory.[4] Often times individuals with Savant Syndrome appear to have knowledge, abilities, or skills, that they have not previously been exposed to or learned, such as being able to play a musical instrument that they have never previously played.[4]

Autism and Down Syndrome are two mental disabilities that are commonly associated with congenital Savant Syndrome, although approximately only one in ten persons with autism possesses savant skills.[4] Savant Syndrome may be described as an internal disability of the mind, such as Autism, that results in an external display of superior ability in regards to specific skill sets, such as remarkable musical talent.

In the case of individuals who develop acquired Savant Syndrome, they have most often experienced an injury or trauma to the central nervous system, such as a blow to the head, which can result in the emergence of savant skills.[4] The internal trauma that an individual experiences, often injury to the left anterior temporal lobe of the brain, may be seen as a trade-off of cognitive abilities for external and new found savant skills.[4] Essentially, internal damage to one area of the brain results in recruitment of intact brain tissue in other areas and there is subsequent rewiring of brain connectivity that results in the release of dormant capacity for skills that are evident through external behaviours and actions.[4]

Looking at the internal structures of the brain and its subsequent connections can provide insight into the reasons in which the external skill sets associated with Savant Syndrome are pronounced. It is especially interesting to study individuals who have developed acquired Savant Syndrome as one may examine the areas of the brain that received damage to gain a better understanding of the causes of the external presentation of savant skills that presents themselves as a direct result of the internal damage.

The psychological study of Savant Syndrome can be related to geology on the subject of plate tectonics and earthquakes. Earthquakes originate from a point that is known as the epicenter and in order to understand the magnitude of an earthquake, the epicenter must be determined.[5] Acquired Savant Syndrome is the result of an external injury, such as a hit to the head, that causes internal damage. Damage is typically to the left hemisphere of the brain and by examining brain scans, the magnitude of the damage may be better understood.[4] The epicenter of an earthquake is located by seismologists using P- and S-waves to determine the located, while the location of brain damage with Savant Syndrome is located using images of the brain. Both techniques or practices allow for the focal point to be determined and the magnitude to be derived.

In regards to plate boundaries, focusing specifically on convergent boundaries, the subducting plate is being pulled internally towards the mantle and therefore the plate loses a portion of its size as it descends. With Savant Syndrome, the brain is also essentially losing a portion of its size, as a result of an injury, in the sense of decreased area in which neural activity occurs.[4] As well, old plate material that has been drawn into the mantle is eventually recycled and forms new plate material. Savant Syndrome is similar in this regard as the brain derives new neural connections in order to try and compensate for the loss of function in other areas.[4]

Geological Perspectives


Creation of island chains through volcanic hotspots

Hotspots are caused by mantle plumes, which are areas in which heat and often rocks from the mantle are rising up towards the surface of Earth.[3] Hotspots are the external presentation of mantle plumes and create the visible features that we can observe on Earth’s surface, such is the case of the island chain of Hawaii.[3]

The lavas which are erupted at the ocean island hotspots of Hawaii have diverse geochemical signatures, meaning that they possess different chemical compositions from within Earth’s mantle.[6] As mantle plumes rise towards to the surface, they entrain various materials, such as subducted oceanic crust, or more primitive materials.[6] The entraining of a variety of materials results in a combination of relatively young oceanic crust from the oceanic plate that is subducting at present time, as well as older oceanic crust that has been stirred in the mantle with more primitive material.[6] The internal recycling of oceanic crust through mantle reservoirs allows for different compositions of chemical complexity to exist within external hotspot lavas.[6]

Within the mantle, oceanic crust that is being internally recycled is continuously stirred which leads to the multi-scale compositional heterogeneity in space and time that is present on Earth’s surface.[6] Studying the chemical complexity of external hotspots lavas provides geologists with the ability to denote the contrasting ages of the material that is rising towards the surface from the mantle, which in turn provides a better understanding of internal convection currents of the Earth.

Hotspots are stationary as the existing mantle plume does not move.[3] However, the oceanic and continental plates that exist on the surface of Earth are in motion and therefore as the plates move, the point at which the hotspot contacts the plate will shift. In the case of island chains, the older islands were once situated above the hotspot during the time of the creation of the island and would therefore have been an active site of volcanism.[3] Younger islands that are currently being formed are therefore active volcanic sites as they are situated above mantle plumes at which lava is rising at present.[3] Examining external features on the surface of the Earth, such as areas where there are new islands being created or external expressions of lava flows, allows us to understand where the internal features, such as mantle plumes, currently exist.

Plate Tectonics

The influence of convection currents on tectonic plate movement

Plate tectonic theory was established to explain surface deformation and the movement of continental plates on Earth’s surface.[7] The process of tectonics is the surface expression of the mantle-lithosphere system, otherwise known as the system of convection currents.[7] Convection currents involve the transfer of energy and heating within the mantle that drives continental drift in the lithosphere, the surface, to move.[7]

In order to gain a better understanding of the inner workings of mantle convection, surface kinematics, the study of surface movement, can be examined to discover what forces move and deform the plates.[7] Another technique that may be used in order to gain information about the role of mantle convection in shaping the surface of Earth is dynamic topography.[7] Dynamic topography is the study of elevation differences on the surface, which is driven by differences in buoyancy within the crust.[7] Both surface kinematics and dynamic topography involve looking at the external processes that are occurring at Earth’s surface in order to gain insight into the internal processes that are occurring within the Earth.

Mantle convection drives plate tectonics and the movement of plates on Earth’s surface results in various plate boundaries. The three types of plate boundaries are divergent, transform, and convergent. Convergent plate boundaries are boundaries at which there is a collision between two plates.[8] Convergent boundaries typically result in subduction zones, with the less dense plate being pushed down under the other. As the slab is descending into the mantle beneath, earthquakes may be generated within the descending slab and at the interface between the two colliding plates.[8] The external destruction that results from the collision of the two plates causes the subducting plate to be drawn internally towards the mantle and it is at convergent boundaries, specifically subduction zones, that the deepest earthquakes occur.[8]  

Studying plate boundaries and the external division of plates on Earth’s surface is useful in that understanding where specific plate boundaries exist can aid in understanding the types of processes that may occur at those specific boundaries. For example, understanding where external convergent boundaries and subduction zones exist aids in predicting where major earthquakes are more likely to occur, as well as where plates are being internally recycled within the mantle.

The Bigger Picture

Both psychology and geology are disciplines in which it is beneficial to employ techniques that look at the overall picture. Psychology involves the connection of the internal, the brain/mind, and the external, the body and behaviour. Geology involves the connection between the internal, the inner processes of the Earth, as well as the external, the surface expressions of the inner workings. In order to gain a comprehensive understanding of both systems, the human body and the Earth, it is necessary to consider all processes as interacting with each other.

Another similar way in which psychology and geology are related is in the fact that there exists systems that drive the varying processes. In regards to Savant Syndrome, the central nervous system, especially incurred damage to the system, plays a large role in the potential development of the syndrome.[4] Similarly, the mantle-lithosphere system, or convection currents, are the driving force behind the movement of plate tectonics and the subsequent external surface features of the Earth.[7]


The psychological study of obsessive compulsive disorder is much like the processes of hotspots on Earth. Hotspots are the result of areas within the mantle that generate intense heat that subsequently allows magma to rise to the surface unbound.[3] Individuals with OCD are unable to control their compulsions and obsessions and therefore the intense obsessions and compulsion that an individual with OCD experiences, may also be seen as a process that is unbound.[2] Examining the internal workings allows us to better understand the external expressions that are evident. In the case of hotspots, the rising magma creates external hotspots, and in the case of OCD, the compulsive thoughts creates external behaviours such as repetitive actions.

The geological study of earthquakes may be related to Savant Syndrome in that there is a focal point, or an epicenter, from which both are derived. The epicenter of an earthquake is established by using P- and S-waves, whereas brain scans are used to establish the area of damage to the brain from which Savant Syndrome, in the acquired case, results. In considering both earthquakes and Savant Syndrome, processes occur that result in outwards features. Earthquakes result in the outward features of shaking and sometimes tsunamis, whereas Savant Syndrome results in skill sets that are evidently remarkable.

Psychology allows us to interpret outward behaviours, such as repeated actions or superior skills sets and connect them to internal workings of the body and mind. In doing so, we gain momentum towards an all-encompassing understanding of the internal processes behind the types of displays and behaviours that are evident.

Geology also allows us to interpret various physical or outward features, such as hotspots or volcanoes and gain an understanding of the internal workings, such as convection currents and the subsequent movement of plate tectonics, that worked to build these features.


  1. Dryden, W. (2018). "Understanding how the OCD mind words and acting constructively: Brianna". Very Brief Therapeutic Conversations. 1st ed.: 109–121 – via Routledge. doi:10.4324/9781351105002-8.
  2. 2.0 2.1 2.2 2.3 2.4 "What Causes Obsessive Compulsive Disorder (OCD)?". BeyondOCD.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Peckyno, R. (2011). "What is a hotspot and what is a mantle plume?". Volcano World: Supplement.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 Treffert,, D. A (2014). "Savant syndrome: Realities, myths and misconceptions". Journal of Autism and Developmental Disorders. 44(3): 564–571 – via doi:10.1007/s10803-013-1906-8.CS1 maint: extra punctuation (link)
  5. "How do seismologists locate an earthquake?". USGS science for a changing world.
  6. 6.0 6.1 6.2 6.3 6.4 MingMing, L., McNamara, A. K., Garnero, E. J. (2014). "Chemical complexity of hotspots caused by cycling oceanic crust through mantle reservoirs". Nature Geoscience – via DOI: 10.1038/NGEO2120.CS1 maint: multiple names: authors list (link)
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Coltice, N., Gérault, M., Ulvrová, M. (2016). "A mantle convection perspective on global tectonics". Science Direct. 165: 120–150 – via Elsevier Science Direct.CS1 maint: multiple names: authors list (link)
  8. 8.0 8.1 8.2 "Plate Tectonics". British Geological Survey.
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