A cliff is defined as a steep rock face. Where marine erosion is powerful, the coastline is eroded to form a cliff. Erosion is concentrated at sea level. A notch is cut in the rock at the level where wave attack is concentrated. When the notch is cut too far, the area above this notch collapses forming a cliff.
These cliffs are found on the coast of Peru
The process of erosion continues and the cliff retreats further and further back. As the cliff retreats, a flat area which is exposed at low tide is left at its base. This feature is known as a wave-cut platform. Watch the video below which explains how wave cut platforms are formed.
The rocks along the coast may contain joints, fissures or other weaknesses. These can be enlarged by wave action, eventually forming a cave.
This cave is found on the coast of California, USA
If a cave is formed in an exposed headland, it may be enlarged until it runs right through this headland. The resulting feature is called an arch. Natural arches can be seen in the photos below.
This arch is found on the west coast of St. Lucia, near the city of Castries
This arch is found near the village of Etretat, France
Over time, erosion may act upon the arch, widening it until the roof collapses. The piece of rock which is left stranded away from the headland is called a stack. In the picture above, a stack can be seen next to the natural arch. The diagram below shows how caves, arches and stacks are formed.
This diagram shows how a cave can develop into an arch and eventually a stack
Coastal Features formed by Wave Deposition
Constructive waves deposit material on the shore. Some features formed by wave deposition are:
Bayhead beach
Beaches are the most common features formed by wave deposition. One type of beach is the bayhead beach. This type of beach is formed when waves deposit material between two headlands. The picture below shows a bayhead beach in Brazil.
This bayhead beach is found in Buzio, Brazil
Bars
These are linear deposits of material which are approximately parallel to the coast. Some are submerged whereas others appear above the waves. They may be stabilized by vegetation and grow large enough to become barrier islands.
A sand bar off the coast of Barton in the Philippines
Some features are formed by a process known as longshore drift. Therefore it is important that this process is understood. Longshore drift is the process by which material is moved along the beach by wave action. This process is responsible for forming coastal features such as spits and tombolos. The video below explains the process of longshore drift.
Spits
These are formed when material is deposited along the coastline by longshore drift. They are usually linear. They are connected to the land at one end and free at the other. Spits usually form where there is a bend on the coastline.
Dungeness Spit, Washington
Tombolo
This is a linear deposit of material formed by longshore drift which joins an island to the mainland. The diagram below shows how tombolos are formed.
This tombolo is found near Hong Kong, China. Notice how the small island is joined to the mainland by the deposition of sand.
10 Examples of Renewable and Non-Renewable Resources
Our demand for natural resources steadily rises every year. Until 1970s, our consumption remained within the natural capacity of our ecosystems to replenish these resources. But since then, we have crossed the threshold of the sustainable resource management, and began using more resources than one planet Earth can possibly provide.
Currently, we live as if we had 1.7 planet Earths available to sustain our needs. This means that we all are living with the growing ecological debt to our planet.
We are using resources as if we had two planets, not one. There can be no ‘plan B’ because there is no ‘planet B. —Secretary-General Ban Ki-moon
We are depleting our planet so much that we have started tracking when this “overshoot” takes place. For example, in 2017, the demand for natural resources exceeded what our ecosystems can regenerate on August 2nd [1]. All resources and ecosystem services we had used in the remaining four months of the last year collectively add to the debt.
What Is the difference between renewable and non-renewable resources?
Our planet’s finite resources and the rate at which we are depleting them has led to a lot of debate about the efficient use of our planet’s natural wealth, as well as the type of resources that we should prefer in order to minimize the impact we are having on our planet.
A key distinction in terms of the resources that are at our disposal is whether they are renewable or non-renewable. So, what exactly are renewable and nonrenewable resources? Renewable resources are resources that are replenished naturally in the course of time. The use of these resources corresponds with the principles of sustainability, because the rate at which we are consuming them does not affect their availability in the long term.
In contrast, non-renewable resources are those that are available to us in limited quantities, or those that are renewed so slowly that the rate at which they are consumed is too fast. This means that their stocks are getting depleted before they can replenish naturally.
Let’s have a look at some examples of renewable and non-renewable resources to get a better understanding of this concept.
Quick Navigation for Examples of Renewable and Non-renewable Resources
Solar energy is a perfect example of a renewable resource. Our planet receives in a single hour the same amount of energy from the sun that the entire world’s population uses in one year!
If we captured and used all this energy at once, we would not deplete the solar power in any way. The sun will still keep on sending its energy our way every day, until it will cease to exist and our planet with it. Therefore, this resource is inexhaustible to our consumption rates.
#2 Wind energy
Wind energy was amongst the first resources harvested by us to improve our livelihoods. Wind pushed our sailboats, and helped mills to grind grains or pump water. No one has really paid special attention to it – some days wind was blowing, some days not. But it has never crossed anyone’s mind that we would run out of wind.
In principle, wind is just air that moves from high pressure to low pressure areas. The different pressures are created in response to changing temperature of the earth surface, which is affected by the amount of sunshine the area receives.
This means that we can use wind as a source of energy for as long as the sun is shining on our planet, without having to worry about overconsuming this resource.
#3 Geothermal energy
The temperature of the earth’s inner core is 5,430 degrees Celsius [2] and it is the hottest part of our planet. This heat is constantly radiating outward, making its way through the outer core all the way to the earth’s surface. This phenomenon is also referred to as geothermal activity. Once it reaches the surface, we can witness this proof of geothermal activity in the form of hot springs, geysers, volcanic lava flows, or steam vents.
The potential to harvest this naturally generated energy is large, especially in areas where the heat can easily reach the surface, like at tectonic plate boundaries, or where the earth’s crust is thinner.
For example, the magma chamber of the supervolcano under the Yellowstone National Park releases the same amount of heat into the atmosphere every day, like six industrial power plants produce to generate electricity [3].
In areas with geothermal potential, we can easily make use of this renewable source of energy for as long as the earth’s core stays hot.
#4 Water
Water is one of the most important resources on our planet. Life without it would not be possible at all.
Throughout the earth’s history, we have always had the same amount of water. This means that the water running from your tap today might have been drunk by a dinosaur some 200 million years ago. Water simply does not disappear, neither can be exhausted by us – it always completes a cycle to return in one form or other.
Sounds wonderful, right? But it’s not that simple. We cannot make more water than there already is, and the amount we have is very limited. This means, if water becomes contaminated with toxic chemicals, or if it was misused for excessive irrigation projects, we are shortening the amount available for us.
The fact that water does not replenish in the same way as other renewable resources do, makes scientists argue whether it belongs into this category or not. Perhaps it cannot be classified based on renewability at all, and should stand on its own as a nice example of nature’s great complexity.
Although, one thing is sure – the energy of moving water is a renewable source of energy for us.
a) Hydropower
It can be generated for as long as river water keeps flowing and any water spent in the process is always recycled back to produce more electricity.
Waves form when the wind blows over large surface of water. In some areas, such as north coast of Canada, Australia, or south of Africa, the wind creates powerful and fairly consistent waves. The amount of energy these waves carry is significant, and can be harvested for as long as there is wind blowing.
c) Tidal energy
Since water spreads over nearly three quarters of our planet, it falls under the influence of gravitational forces between the earth and the moon. Simply said: the gravity of the moon always pulls the ocean water into a bulge on the side of the earth that currently faces the moon. This is how tides happen.
Since tides are directly created by the constant movement and mutual constellation of our planet and the moon in the solar system, tidal power is one of the most consistent and predictable sources of renewable energy available to us.
Video – How Does Tidal Power Works
Video credit: Student Energy / Youtube
#5 Air
The air we breathe is a carrier of compounds crucial for metabolism of all living organisms. Even our industrial processes depend on the access of oxygen as a catalyst to chemical reactions. The combustion of fossil fuels to supply our energy would not be possible without the access of oxygen, neither would be the ignition of a fire that enabled our ancestors to survive cold weather of the last ice age.
This makes air one of the most important natural resources, which is to our advantage also considered a renewable resource. Even though modern anthropogenic activities pollute air at an unprecedented level, many vital natural processes such as photosynthesis are constantly replenishing clean air again.
For example, one acre of forest absorbs six tons of carbon dioxide emitted from industrial activities, and produces four tons of oxygen in exchange [4].
#6 Soil
Yes, even soil is a renewable resource. In healthy ecosystems, various natural processes like decomposition and nutrient recycling replenish our soils in sustainable ways. The problem is that a sustainable cycle in nature lasts centuries, and does not take into account our excessive exploitation of this natural resource.
Today, the rate of soil depletion across the globe is outstripping the rate of new soil formation. Just the United States loses every year soil 18 times faster than is replenished [5]. Globally, it is estimated that 33 percent of our soils are degraded due to the erosion, salinization, compaction, acidification or chemical contamination [6]. All this damage is due to our mismanagement of this resource.
Luckily, we are also capable of reverting this process. The same way we speed up soil degradation, we can apply techniques that make soils fertile again and accelerate their recovery rate. One such method is to perform biointensive farming, or follow other principles of sustainable agriculture and land use.
#7 Cultivated plants
Trees, crops, fruits, vegetables could also be considered renewable resources. In fact, all the plants we cultivate for food, energy generation or product manufacture represent for us renewable resources.
We can look for example at trees. They can be planted, grown, trimmed or even felled, and then more trees can be replanted in their place. Trees provide one precious raw material – timber. About 40 percent of all timber in the world is needed in paper production. The remaining 60 percent are used for other purposes such as a building material, furniture or other everyday objects from cooking utensils to decorative ornaments [7].
The same is true about food crops such as wheat, corn, sunflower, and many other we plant to produce food for us or our livestock. From one field, we can easily harvest two or more different varieties of crops in one year period and then repeat the same cycle for many more years.
#8 Biomass energy
Biomass energy has been used by us throughout our history mainly for cooking and warming our homes with fire. It is the energy released from burning plants and animal-based organic materials such as manure. Biomass is a renewable resource for the same reason as food crops are – we can simply regrow once harvested plants, or collect more manure from our livestock every day.
For example, a hybrid species of a poplar tree is one of the most grown trees for biomass production in the United States. It can reach 30 feet in just five years, and is harvested in maximum seven year cycles. Once harvested, the trees do not have to be replanted from seedlings again. New shoots start to grow from the stumps that remained behind, repeating the cycle right from the beginning [8].
#9 Biofuels
Biomass can be also used to fuel our means of transport. How? The answer is simple – by transforming it into biofuels.
According to the definition, “biofuel is a term that refers to a number of liquid fuels produced from biomass using biological processes.” The most common types of biofuels are ethanol and biodiesel. Ethanol is usually derived from the fermentation of sugarcane and corn starch, while biodiesel is processed from vegetable oils or animal fat.
As superior as it may sound, the animals we breed and manage their populations to get some products from them represent a renewable resource as well.
10 Examples of Non-Renewable Resources
#1 Coal
Coal is one of the most used fossil fuels. It has formed more than 300 million years ago in swamps covered by water. Later, swamps dried up and all organic material in different stages of decay got buried underneath multiple layers of soil.
Coal is non-renewable not only because the process of its creation took millions of years, but also because the climate on earth was completely different at that time. This means that we cannot replicate the same conditions to encourage creation of new coal reserves, and the deposits we have been overexploiting since the last century are quickly running out.
According to the information from the World Coal Association, at our current rates of consumption, we have enough coal for the next 150 years [9]. Other sources mention 118 years or even less [10]. To predict how much coal is left in the world is not an easy task because of many factors we need to take into account. One of them is for example the increase in demand of many fast-growing economies such as China or the United States.
In the end, one thing is inevitable – we cannot rely on coal much longer because sooner or later the deposits will run out.
#2 Oil
Oil is probably one of the most well-known non-renewable resources alongside coal. It is a liquid fossil fuel made up of fossilized animals (possibly even dinosaurs) thousands of years ago. When extracting oil from the ground, it comes out in the form of black crude oil. Crude oil is then refined into different products we use on a daily basis such as gasoline, diesel fuel or heating oil [11].
The story of the oil’s downfall is similar to coal. Given that only in the United States an average of about 19.4 million barrels of oil is consumed every day, it is clear that we are using our oil reserves much faster compared to how fast nature can replenish them [11]. Already at this moment, scientists estimate that oil is probably the least abundant fossil fuel, which is likely to run out fairly soon.
#3 Peat
Peat, commonly found in the UK, Ireland or Finland, is a soft organic material consisting of partly decayed plant matter together with deposited minerals [12]. Peat can be dried out and used as fuel but it is also an important raw material in horticulture and for potting.
Some peat industry representatives and academics believe that peat is a slowly renewable resource, but in reality, a peat bog takes thousands and thousands of years to form. So, if one considers the rate at which peat is being used either for energy or as a growing medium, then it is evident that it is not a renewable resource.
Peat bogs are considered such important parts of our ecosystems that in most countries they are protected or considered conservation areas.
#4 Uranium
You may have heard the ongoing debate over the renewability of nuclear power. While some people claim that nuclear power on its own perfectly fits the definition of a renewable source of energy, it is uranium, the commonly used nuclear fuel, which does not fit into the scheme.
Uranium is a radioactive element found in low amounts within all rocks on earth. It is a non-renewable resource because of its cosmic origin. The isotopes of uranium were formed 6.6 billion years ago in supernovas and do not naturally regenerate. In fact, the radioactive decay of the natural deposits of uranium is what keeps the earth’s core in a liquid form [13].
Nuclear power plants use only one isotope of uranium (U-235) for fuel because its atoms are easily split apart. To get this naturally rare isotope, uranium ore has to be mined in large amounts and undergo the process of enrichment.
Given today’s consumption rate where nuclear energy makes about 11% of all energy sources worldwide, the Nuclear Energy Agency estimates that we have around 200 years supply of uranium to run our reactors. After that, this resource is likely to run out [14].
#5 Gold
The eternal symbol of wealth and power. This yellow shining metal has enchanted many great rulers in the history, and gave reasons to countless crimes, as if people have always known that there is something special about this precious metal.
Indeed, there is!
It was created from the collisions of neutron stars when our solar system was formed [15]. Knowing the cosmic origin of gold offers probably a good-enough explanation why this resource is not renewable.
Our history of using gold reaches as far as the rule of Egyptian pharaohs some 3,400 years B.C., followed by many periods of extensive exploitation of this resource – like the famous Gold Rush in 1850s. Even today, around 2,700 tons of new gold are mined every year.
We don’t use gold only to satisfy our vanity, it is a great conductor of electricity needed for the manufacture of cell phones, computers and other high-tech devices. Gold is widely used in the medicine as well. Besides being a part of various treatments such as of tuberculosis or arthritis, it has been lately tested as a possible cure to cancer [16].
While we keep increasing our dependence on gold, the natural reserves of this resource are thinning. It is only a matter of time until we hit that final deposit.
#6 Aluminium
Aluminium is the key resource for meeting a lot of our societal needs. From packaging to making parts of automobile or railway cars, aluminium is a very versatile material.
Even though aluminium is the most abundant metal on Earth and one of the most common elements in the universe [17], it is still considered a non-renewable resource, as it does not get replenished on its own like for example timber does.
Unlike gold, aluminium started to be abundantly used in the late 19th century, but it did not take us long to catch up with exploiting this resource. According to statistics, the demand for aluminium has grown thousand times just in the span of two years between 2013 and 2015 [18].
The positive news is that as the aluminium industry keeps booming, so do the recycling programs. To our advantage, aluminium can be fully recycled, which enables us to use this resource repeatedly and more efficiently.
#7 Sand
Being the third most used natural resource after air and water, sand is an essential material to sustain our way of life. But unlike air and water, sand is a non-renewable resource. In the nature, sand is made of different minerals and rock sediments that are broken into tiny fragments after being battered by the elements for thousands of years.
Nowadays, 40 billion metric tons of sand and gravel are extracted every year for the construction industry, glass manufacturing, and other uses such as land reclamation or oil exploration [19]. In fact, nearly all built structures contain sand in some form. Every house, large shopping mall or paved road is made with concrete, which is a mixture of gravel, sand, cement and water.
With more and more urban development projects, our need for this resource is not likely to stop any time soon. But there is a problem – sand is becoming so scarce that overnight thefts and illegal activities of so called “sand mafia” have started to flourish.
If we do not tackle the problem and focus on sustainable use of this resource from this moment, we might be forced to look for alternatives to sand very soon.
#8 Iron
Theories suggest that most of earth’s core is composed of iron. This metal can be also found in the composition of the sun and stars, so we can say that it is a common element in the universe. We even have it in our blood (literally). But from the perspective of a resource, iron belongs to the category of non-renewable resources because it does not get naturally replenished.
Throughout the history, we have made diverse objects from iron, including swords, dishes, or other daily-use items. Even these days, 90 percent of metal entering our refineries is iron. Iron is for example used to make stainless steel. We are all familiar with stainless steel cutlery or skillets. Iron also represents one of the main building blocks in the construction industry.
Overall, iron is an abundant resource on earth and on rare occasions, some more even falls from the sky. As numerous geologists documented, iron is a common element in meteorites. In fact, some of the first iron artefacts from the old Egypt are made of meteoritic iron [20].
#9 Phosphate rock
As the name suggests, phosphate rock is the main source of phosphorus. Phosphorus is the key nutrient in agriculture. Without phosphorus, plants simply cannot grow, as this essential nutrient promotes root formation, seed development, and has an irreplaceable role in photosynthesis.
Phosphate fertilizers have been supplying phosphorus to our crops, which are grown on farmed soils for decades. More than 85 percent of phosphate rock mined every year is used to manufacture fertilizers, and the remaining 15 percent are transformed into livestock feed supplements or into other compounds. After all, even our energy metabolism and skeletal system requires this essential nutrient for the healthy development.
The problem is that the deposits of phosphate rock do not get any bigger, while our demand for this non-renewable mineral skyrockets every year. According to a belief of a Swedish researcher Dana Cordell, if the demand keeps growing as it does now, it will exceed the global supply as soon as 2035 [21].
If we do not learn to use this resource more efficiently without wasting or misusing it too much, our capacity to feed the growing population might be seriously undermined.
#10 Rare earth elements
“The seeds of technology.” The science of the modern technology stands on the unique properties of rare earth elements.
Thanks to their magnetic, electrochemical, and luminescent characteristics, these elements enabled us to develop small and yet very powerful electronic devices. They also gave us the ability to harvest green energy, as the example of magnetic neodymium in wind turbines demonstrates.
Rare earth minerals can be found scattered in the earth’s crust. They are not renewable because the story of their origin is the same as the one of uranium. They formed in supernovas billions of years ago. Even though, we are not facing the shortage of their supply at the moment, their amount on earth is finite.
