Simplified view of the submarine real, showing the location of most submarine canyons relative to the continental landmass and slope.

Turbidity currents are dense mixtures of sediment and water that move under gravity down the continental slope and into ocean basins. They can form when underwater landslides occur and disintegrate, when oceanic storms whip up sediment from the sea floor, and where rivers discharge sediment into the ocean. Over time these turbidity currents erode the seafloor and carve out vast submarine channels and canyons. The turbidity currents that carve these canyons can transport as much sediment in one week as all the world’s rivers do in one year, and are some of the largest mass transport process operating on our planet.

Schematic showing the different types of mass transport that occur on the continental slope. Turbidity currents transport sediment to the more distal areas of the ocean.

The Nazaré canyon, off the coast of Portugal, is one of the most spectacular examples of a sinuous submarine canyon. It begins 50 m offshore the town of Nazaré, and extends down to a water depth of 5 Km. Its deepest point relative to the surrounding seafloor is 1 Km, and at its widest it spans 9 Km. In addition to being one of Europe’s largest submarine canyons, it is also home to a unique marine ecosystem consisting of mesopelagic and benthic organisms.

Bathymetric map of the Nazaré Canyon and the Iberian Abyssal Plain, off the Central Portuguese Margin.

In recent decades human impact on the oceans has become strikingly clear. The vast quantity of plastic and other discarded material in the oceans is soon estimated to outweigh the quantity of marine fish. Despite their extreme depth, submarine canyons have not escaped the problems associated with marine pollution. Aluminium and plastic refuse have been observed by ROV cameras at a depth of 4,500 m in Nazaré Canyon.

Images of marine litter in the deep sea (Image credit: MBARI).

Submarine canyons are unique environments, and they are host to unique species and ecosystems. However, like all other habitats they are susceptible to pollution and degradation. While we know much about submarine canyons, we know relatively little about the ecosystems that exist within them, as well as the effects that environmental degradation is having on their trophic structures. Considerably more effort should be afforded to understanding this secret world.

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Contrary to popular belief, euphemisms, idioms and trite sayings often have little relevance to real life. Foraminifera on the other hand, lend credibility to the notion that big things do indeed come in small packages.

Foraminifera are small, single-celled marine plankton; more specifically known as Protists. They live at various depths within the oceans but are most commonly found in shallow water depths (<50 m). Many species of Foraminifera feed on small marine plants and other detritus, while some are carnivorous and feed on other smaller species. They have lived in the oceans for millions of years and are found throughout every ocean on Earth. Their ubiquity and persistence through time makes them remarkably useful in studying ancient oceans.

Many species construct their shells out of calcium carbonate (CaCO₃). Other species construct it using fragments of other shells, or even grains of sand. The CaCO₃ which makes up the shell of many species can contain a record of a large number of environmental variables that can help us understand the past ocean. Carbon and Oxygen both have 2 dominant stable isotopes (¹²C, ¹³C, ¹⁶O and ¹⁸O respectively). The record of past changes in these isotopes locked in these Foraminifera shells can be used to infer changes in water mass distribution, changes in terrestrial ice volume, and nutrient distribution in the oceans.

Aside from basic stable isotopes, Foraminifera also contain useful radioactive isotopes. One of these isotopes called radiocarbon (¹⁴C), is particularly important to paleoceanographic studies. When Nitrogen 14 (¹⁴N) in the upper atmosphere is bombarded by incoming solar radiation, it gains a proton and becomes ¹⁴C. This radiocarbon diffuses into the oceans and is taken up in small amounts into the (CaCO₃) shells of the Foraminifera. By measuring how much of this radiocarbon is left in an ancient shell we can know its age and the age of the sediment which surrounds it. This helps us tie down the ages of important ocean events like landslides and glacial changes on land.

Several additional proxies exist including Uranium decay series elements. These are used to detect the source of water masses by using their chemical fingerprint to trace the source of their suspended and dissolved material. Even the numbers of Foraminifera can help us. Certain species thrive in cold water, while others prefer the warm waters of the sub-tropics and equatorial regions. Using the percentage of these different species in a sediment sample, we can compare this past assemblage with modern ones and infer sea surface temperature changes that help us understand the effect of glacial cycles and climate change on the worlds oceans. Calcium/Magnesium ratios in formainiferal shells can also give us an indicator of temperature, while Barium/Calcium can be used to indicate palaeosalinity. The list of these ‘proxies’ goes on, and existing ones are often refined or replaced with new ones.

To sum up, these grains of sand may only be the remains of tiny dead critters, but they provide us with a immensely powerful tool in our quest to understand the oceans and their role in the changing climate.

Josh Allin

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Photo: Me in Svalbard, 2014

I am part of the larger ‘Arctic Research Program – Landslide Tsunamis’ project that aims to evaluate the role of climate change on the frequency of submarine landslides in the North Atlantic. The goal of the project is to determine any potential risk which may exist to the UK coastline from possible tsunamis, which can be created by submarine landslides. I have also contributed research to the ASTARTE project, which aims to increase tsunami resilience in the North East Atlantic and Mediterranean regions, and to improve the preparedness of coastal populations to save lives and assets.

Photo: Me presenting my research on submarine landslides at the European Geosciences Union, 2016

I first became interested in geography and Earth sciences during my GCSEs, after which I did geography for A-level. I was accepted onto a bachelor degree in Earth science at University College Cork and graduated in 2011. The following year I completed a masters degree in environmental science at Trinity College, Dublin. In 2013 I began my PhD the University of Southampton, and completed it in December 2016.

Photo: Me (far left) and the Landslide-Tsunami team in the North Atlantic aboard the RV Pelagia, 2014

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Given that your first task is to give us examples of images which you feel best represent the oceans, here are a few which I feel highlight their significance.

1. Cliffs of Moher, Ireland

Few places give us a more spectacular view of the influence of the oceans on Earth. Over millions of years they shape the continents through the processes of erosion and deposition, redefining landmasses and providing one of the most important environments we have – Coastlines.

2. January storms over the UK and Ireland

This storm, which hit western Europe during January of this year, highlights the power of the oceans over the weather systems of continents. The oceans play a large role in the redistribution of the heat from the sun; the Gulf Stream being one such example. This heat redistribution creates atmospheric systems which dominate and define the climates of many parts of the world.

3. Algal blooms off the South-West of Ireland

Similar to forests, the oceans are now considered to be vital in contributing oxygen to Earth’s atmosphere. Marine Cyanobacteria (algae) alone contribute nearly 20% of oxygen involved in chemical cycling between the oceans and the atmosphere. This photosynthetic marine life also forms the basis of nearly all food-webs in the oceans, sustaining countless numbers of species.

4. Shoal of Bigeye Travellies in Cabo Pulmo National Park, Mexico

The smallest of organisms, such as cyanobacteria and other photosynthetic life, support vast quantities of large marine life. Much of this marine life is vital to coastal communities and their economies.

5. Before and after satellite image of the 2004 Indian Ocean Tsunamis, Phuket, Thailand

The tsunamis which occurred in the Indian Ocean in 2004 claimed an estimated 230,000 lives and displaced roughly 1.6 million people from their homes. This image highlights the raw and unpredictable power of the ocean. Events like this one can be devastating and are evidenced in the historical record of many countries; hence why they are one of the focusses of my PhD.

Image credits:

1. Cliffs of Moher Visitor Centre

2. UK Meterological Office

3. Jeff Schmaltz, MODIS Rapid Response Team/NASA

4. Octavio Aburto, National Geographic

5. NASA: Climate Time Machine

The post What does the ocean mean to me: Josh Allin appeared first on Exploring our Oceans .

While most people are aware of terrestrial landslides, few people  know that landslides also occur underwater. Because these canyons have steep sides, they are prone to failure from time to time, after which the sediment flows down the canyon, sometimes for hundreds of miles. This landslide more closely resembles a sandy soup. Here is a video in which you can see this process occurring.

These landslides can vary hugely in size, from small like the one in the video, to landslides that could theoretically cover the whole of the UK (Don’t worry, we’re safe from being buried). These landslides do pose one particular risk though: They can cause tsunami waves!! Here’s a video showing how that can happen. This video is observing from an underwater perspective and the waves generated above it are actually on the surface of the ocean

Landslides are a very significant oceanic process, and one which we don’t fully understand. my research focusses on records that these landslides leave behind, and what they can tell us about them. The number of landslides has changed over time, and there are many possible causes, which all helps us analyse the risk of tsunamis. This research will also help us understand how climate affects landslides, and how future climate change might change their frequency

The post My research; Josh Allin appeared first on Exploring our Oceans .

Hi, I’m Josh and I’ll be one the facilitators here on the Exploring our Oceans MOOC.
My journey into Earth and ocean sciences began at A level Geography, where I became interested in physical geography and geology. This led me to undertake a Bachelor of Science (B.Sc) degree in Earth science at University College Cork. While at UCC I studied many different disciplines of Earth science, including oceanography, geology, climatology and palaeontology. As part of the degree we got to visit loads of interesting places, and even went as far as the sunny south of Greece, where we some saw exceptional geology and some ancient Greek ruins from nearly 3000 years ago. The degree was great fun and Cork is a fantastic place to study science.

This degree led me into a Masters (M.Sc) degree at Trinity College, Dublin focussing on environmental sciences. This degree encompassed aspects of coastal and estuarine science, hydrology, environmental chemistry and environmental change. My M.Sc thesis involved the study of marine geology and geochemistry, as well as marine micropalaeontology, to better understand the dynamics of marine sedimentation from glaciated margins along the west coast of Ireland. For the the residential field trip we got to spend a week in the sun near Faro in Portugal, where we visited coastal, estuarine, and lagoon environments. We even got to tear across the lagoon in a powerboat

Following on from my masters, I gained a NERC funded Ph.D position here at the National Oceanography Centre (NOC) in Southampton, focussing on marine geology and submarine geohazards. My research evaluates the frequency of large submarine landslides within open slope and submarine canyon settings, and the role of climate and glacial cycles in the triggering of these landslides. My research has taken me to Norway, Italy, Spain, The Netherlands, The Arctic, The Irish Sea and to the North Atlantic aboard the research vessels Celtic Explorer and Pelagia. Oceanographic research is an exciting field with many opportunities for excursions and exploration. I hope you enjoy the course as much as we do.

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Seeing as the topic of the week is scientific cruises, here’s a few images from a cruise I participated in back in Feb ’13. It’s just a little flavour of what living on a research vessel is like.

The cruise was part of the INFOMAR programme whose task is integrated sea bed mapping of the Irish continental margin. More information can be found here. The vessel was the Irish research ship The Celtic Explorer, operated by the Marine Institute. It’s a 65 m ship and can berth up to 20 scientists and 11 crew members for up to 31 consecutive days.

The cruise had a number of aims; increased resolution seabed mapping using multibeam bathymetry was one aspect of the cruise which took place at night. Daytime activities were dedicated to sediment coring, drop-camera work and shallow seismics

Here are a few of the tasks underway

Living conditions on the ship are surprisingly comfortable, as long as you can get used to the constant pitching and heaving of the ship. The food is also good (a man can gain a fair amount of weight on a scientific cruise!)

Working conditions are also comfortable (depending on the task at hand!). Bathymetry work was mostly carried out at night, meaning some of us were on duty from 8pm to 8am, then up all day to help with daytime activities. Only a few hours of sleep in a 24-hour period is not uncommon on research cruises, given how much they cost and how little time there is to collect data.

All in all, cruises are one of the most exciting aspects of oceanographic research. It puts one right at the forefront of the science. July of this year will entirely occupied by an Arctic cruise for me and Millie and our colleagues, which will take us to nearly 80 degrees North in the Atlantic Ocean, well inside the Arctic circle. The cruise will involve a huge sediment coring effort to help understand how the frequency of large sediment failures might change in response to climate change in Atlantic and Arctic basins, and what effect this might have on the UK coastline in the form of landslide-generated tsunamis.

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Given that the topic of landslides came up during week 1 of the course, here is a little about my daily work on submarine landslide deposits.

First of all, how do we learn about submarine landslides? Seeing as the ocean is so large and we can’t really have any cameras permanently on the ocean floor with which to observe them, we have to primarily look at their aftermath (i.e. the material they leave behind). This material is often a number of meters thick, meaning we have to use specialist equipment to recover it, termed corers. These corers can penetrate from a few to a few hundred meters into the sea bed and retrieve a vertical section, giving us a look at what lies beneath. Here is an example of a core section showing a landslide deposit:

One important aspect of the study of landslides, one which was discussed in week 1, is prediction. The 2011 tsunami which struck the Eastern coast of Japan was caused by an earthquake-triggered landslide. Knowing the destruction that these events can cause, determining how often they occur is important in understanding when they might happen again. For this we need dating techniques. As some of you may know, dating is done using a number of methods, the most common of which is called radiocarbon dating. In order to gather material to date, we need to sample the material just underneath the landslide (landslides don’t tend to have any datable material), known as hemipelagic sediment, or ‘background’ sediment. This sediment contains the remains of a very important little group of organisms called Foraminifera, which we can use as datable material. Their remaining shells contain Calcium Carbonate, which contains carbon we can test and calculate an age based on the amount of radiocarbon remaining. Here are some Foraminifera ready to be picked. They’re pretty small!

Landslides generally occur many times throughout history in deep sea basins, and so build up on top of one another, with datable material in between. Once we have dates for the landslides we can begin to unravel the frequency of the events and compare the occurrence to climatic events, possible sediment loading from erosion and other possible triggering mechanisms.

Aside from the research, I act as a teaching assistant on a number of undergraduate modules, which is always a good laugh. I also edit the postgraduate newsletter, which is just a bit of a spoof really, but it’s good fun writing it.

The post PhD “Life” appeared first on Exploring our Oceans .

Given that your first task is to give us examples of images which you feel best represent the oceans, here are a few which I feel highlight their significance.

1. Cliffs of Moher, Ireland

Few places give us a more spectacular view of the influence of the oceans on Earth. Over millions of years they shape the continents through the processes of erosion and deposition, redefining landmasses and providing one of the most important environments we have – Coastlines.

2. January storms over the UK and Ireland

This storm, which hit western Europe during January of this year, highlights the power of the oceans over the weather systems of continents. The oceans play a large role in the redistribution of the heat from the sun; the Gulf Stream being one such example. This heat redistribution creates atmospheric systems which dominate and define the climates of many parts of the world.

3. Algal blooms off the South-West of Ireland

Similar to forests, the oceans are now considered to be vital in contributing oxygen to Earth’s atmosphere. Marine Cyanobacteria (algae) alone contribute nearly 20% of oxygen involved in chemical cycling between the oceans and the atmosphere. This photosynthetic marine life also forms the basis of nearly all food-webs in the oceans, sustaining countless numbers of species.

4. Shoal of Bigeye Travellies in Cabo Pulmo National Park, Mexico

The smallest of organisms, such as cyanobacteria and other photosynthetic life, support vast quantities of large marine life. Much of this marine life is vital to coastal communities and their economies.

5. Before and after satellite image of the 2004 Indian Ocean Tsunamis, Phuket, Thailand

The tsunamis which occurred in the Indian Ocean in 2004 claimed an estimated 230,000 lives and displaced roughly 1.6 million people from their homes. This image highlights the raw and unpredictable power of the ocean. Events like this one can be devastating and are evidenced in the historical record of many countries; hence why they are one of the focusses of my PhD.

Image credits:

1. Cliffs of Moher Visitor Centre

2. UK Meterological Office

3. Jeff Schmaltz, MODIS Rapid Response Team/NASA

4. Octavio Aburto, National Geographic

5. NASA: Climate Time Machine

The post What does the ocean mean to me? appeared first on Exploring our Oceans .

I’m Josh and I’ll be a facilitator here on the ‘Exploring our Oceans’ course. I’m also a PhD student at the National Oceanography Centre, Southampton. I am part of the larger project which is evaluating the role of climate change on the frequency of submarine landslides in the North Atlantic and Arctic Oceans. The goal of the project is to determine any potential risk which may exist to the UK coastline from possible tsunamis which can be created by submarine landslides.

More information on the larger project can be found here

My current research is focussed on the timing of submarine landslides in the Iberian Abyssal Plain (IAP), off the coast of Portugal.  Landslides documented in a number of deep-sea basins offshore Portugal have been shown to respond in the long-term to climate dynamics, but also to past earthquakes. This research aims to clarify the various controls on the observed landslide events by comparing their frequency with longer term climatic variability, and to establish whether any overarching palaeoseismic influence exists from the Azores-Gibraltar boundary to the South. Our dataset consists of a deeps sea cores taken from below 4,500m depth in the IAP, which penetrate a maximum of 12m into the seabed.

Current analytical methods involve ITRAX-XRF geochemistry to establish turbidite provenance, Geotek MSCL to examine core physical properties and other geochemical methods for age determination. These methods will enable us to reconstruct landslide histories along the margin and incorporate these into the larger evaluation of landslide hazard along the Atlantic and Arctic margins.

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