Need help with what to do in your garden?

Q What constitutes a chalky soil?

A All chalky soils will have a chalk layer below them, but can be anything from the light, peaty soil found on top of The Downs to deep, rich clays.

Typically, they contain a lot of flint, which is a nuisance when cultivating and causes problems when digging. Chalk soils don’t hold on to water successfully. The other properties of a chalky soil are dependent on their other components, especially the clay content.

Caption: Digging a hole exposes the layer of chalk underneath

Q How do I know if my soil is chalky?

A Expect to find chalky soil in areas where white chalk is exposed, either by deep digging, local roads, blown-down trees or building work.

Small pieces of white chalk in the soil are an obvious sign, though often these are not apparent, especially where the soil is deep and clay-like.

Chalk is almost entirely composed of calcium carbonate. Weak acids like vinegar added to the soil will froth if calcium carbonate is present. This test will reveal particles of chalk too small to recognise by eye.

An extra check is to use a soil test kit and check the pH.

Q Is chalky soil always bad?

A Chalky soils have both good and bad points for the gardener. They are well-drained and warm up quickly in the spring. You can cultivate and walk on them after rain and they usually have excellent structure. Plants thrive on them if given enough water and nutrients.

However, chalky soils can be shallow, drought-prone, poor in plant foods and very alkaline. Some chalky soils contain a lot of clay, and trampling the soil when wet can compact the subsoil so you may have to break it up by deep digging.

Q How do I manage a chalky soil?

A Shallow chalk soils suffer from drought. They are light, with a low clay content, and are full of flint. Adding organic matter will boost their water-holding abilities. Use at least one wheelbarrow load every 2.3m2, or add a mulch at least 5cm deep to damp soil. Organic matter will not last very long in such soils and repeat applications are likely to be needed every year. Firming these soils by treading before sowing and after planting will often help plants to survive.

The presence of chalk means the pH is high, or alkaline. This makes it unsuitable for fruit and acid-loving plants such as heathers or rhododendrons. Nutrients are often in short supply too. Organic matter will help, otherwise add 100g a sq m of a general fertiliser, each year in the spring and top up with 70g a sq m later in the season, whenever plants look as though they need a boost. If you need to add extra nitrogen fertilisers, use sulphate of ammonia which tends to acidify soil, though it will take years to have a significant effect.

Nutrient deficiencies are commoner on thin, chalky soils than elsewhere. If plants look as though they are lacking food, add extra nitrogen fertiliser. Often, this will allow plants to overcome the shortage by growing better root systems, enabling them to find nutrients more effectively.

To keep nutrients at a good level, add organic matter. Deeper chalky soils are often more clay-like. The mixture of clay and chalk in these soils makes them excellent vegetable growing soils, but they do not grow fruit well.

When moist, these soils are sticky and unpleasant to cultivate, although not as intractable as a clay soil. They also tend to hold less water, so plants need watering sooner. Adding organic matter is helpful, but the excellent structure of chalk soils means that the benefit from organic matter is less crucial than in sandy or clay soils.

Aim to dig chalk soil in the autumn, leaving tennis ball-sized lumps. If the lumps are bigger, you might not be able to break them up in the spring, leaving clods of wet soil on the surface. If they are smaller, they may fall apart in the winter and then break down into a structureless mass.

Leave the soil level, or you will have to do so much raking and cultivating that you are likely to bring coarse, soggy lumps to the surface that will be very difficult to turn into a seedbed. Aim to create a seedbed with the minimum of raking and cultivating. Too much and you will destroy the soil’s structure, without which it will collapse over the newly sown seed making a hard, airless layer through which the young seedlings will find it hard to escape.

Often, the soil will look dry on top, but will be saturated below, so avoid treading on it until it is drier; you may have to wait for some time. Ideally, make beds and borders that can be worked from paths. Narrow beds, about 1.2-1.5m wide, are ideal for vegetable growing. Use stepping stones to avoid trampling on wider beds and lawns.

Caption: Mulching is an important way of improving chalky soil

Q Can I avoid digging a chalky soil?

A With their excellent structure, chalky soils make very good no-dig gardens or raised beds. Ideally, add plenty of organic matter before finishing with digging. Are there any other plants I should avoid growing? Potatoes are prone to scab damage in chalky soils. Choose scab-resistant kinds – ‘Wilja’ and ‘Pentland Crown’, for example – and water as freely as possible.

Modern hybrid roses often fail to do well on chalk.

Q How do I recognise nutrient deficiencies in chalky soils?

A Magnesium deficiency is common on chalky soils. Look out for pale leaf centres and dead tissue next to the midrib. The base of shoots are likely to be worse affected than young leaves. Brassicas take on red or purple tints. Trees may have brown areas between the veins. Check the diagnosis by dissolving 30g of Epsom salts in 10 litres of water and spray the foliage of affected plants with the solution.

Iron deficiency causes yellow leaves and is due to the iron in the soil being ‘locked up’ by the alkaline conditions. Treat this with chelated iron compounds.

Q Should I do a soil test?

A A cheap soil testing kit will give an idea of the soil pH. Acid soils have a pH of less than 6.0, alkaline ones are higher than 7.0, while soils with a pH of 6.0-7.0 are about right, or neutral.

Caption: Testing your soil will confirm its pH

Q How can I grow ericaceous plants if my soil is chalky?

In large gardens on alkaline soil you sometimes see raised beds filled with peat used to grow heathers, rhododendrons and other lime-hating plants. However these are quite labour intensive to create and maintain, and the lime still seeps up from the soil below.

Beware the water supply however – chalky areas usually have alkaline tap water. Ideally, collect rainwater for your acid-loving plants.

Q Which plants will do well on chalky soils?


Spinach beet, sweetcorn and cabbage family vegetables do well, but avoid celery or marrows.


Caption: Mahonia x media ‘Charity’ does well in chalky soil



Clematis and lonicera

Herbaceous perennials

Wild flowers

Shallow, nutrient-poor chalk soil can be ideal for wild flowers that naturally grow on these soils.


Many shrubby herbs originate from areas with dry, limey soils and thrive on chalk. These include bay, thyme, marjoram, fennel, rosemary and sage. Leafier herbs that like moisture, such as mint and parsley, will do less well.

Q: How do you add topsoil?

Above: One good reason you may need to buy topsoil: to replace soil lost to erosion. Photograph by Matthew Williams, from Hardscaping 101: Erosion Control.

A: Ideally, you should till the soil that’s already in your garden (especially if it’s compacted) and add a 3-inch layer of blended topsoil, tilling it all together again to create a 6-inch-deep surface layer; this will best mimic real topsoil. “You do not want to simply lay a three-inch layer on the surface of a soil and attempt to plant into that layer,” advises Dr. Murphy. “Creation of artificial layers almost inevitably creates drainage problems. Roots may proliferate in that layer and never grow deeper into the mineral layer.” Spring or fall, when rains keep soil moist and encourage biological activity and decomposition, are the best times to add topsoil.

Q: Do you need to add anything else to store-bought topsoil?

Above: See more at Walled Gardens: An Organic and Picturesque Plot at Old-Lands in Wales. Photograph by Britt Willoughby Dyer.

A: “Probably not compost, since most blended topsoils and bagged topsoils already have or are composed of compost,” says Dr. Murphy. As for fertilizers, you’ll need to have your soil tested to find out what nutrients your soil could use more of.

Q: Is it necessary to buy topsoil at all?

Above: Amending your existing topsoil with compost is a more sustainable and better option than hauling in store-bought topsoil. Photograph by Jim Powell, from Composting: Are You Obsessed?

A: If you simply need to increase soil volume—whether it’s to replace soil that has eroded or to even out property or to create a garden from scratch—then yes, buying topsoil is an inexpensive way to do it. But if you’re interested in encouraging a healthier, more fertile topsoil, according to Dr. Murphy, amending what you have with compost is preferable to buying topsoil. “The more we can re-create natural topsoils, the less fertilizer input is needed—and long-term sustainability can be achieved. For example, it has been shown that very old lawns require less fertilizers and less irrigation,” she says. “In most cases, improve what you have with soil amendments, unless you specifically need greater soil volume.”

Do you have a question about your first garden? (Or your second or third or fourth garden)? Let us know what they are in comments section below, and I’ll try to answer them in upcoming installments of Your First Garden. In the meantime, find more beginner gardening lessons here:

  • Landscaping Ideas: 11 Design Mistakes to Avoid
  • Landscaping 101: How to Deadhead Flowers
  • Houseplants 101: How to Propagate Plants

Garden Myths – Learn the truth about gardening

You have probably heard that humus is an important part of your soil, but few people know what it is and why it is important. There are many myths about humus that need to be cleared up.

It turns out that humus may be the most important thing in soil: more important that dew worms, and organic matter, but it gets so little attention. This post will have a closer look at humus to better understand how we should be gardening to create and maintain humus rich soil.

We are talking about humus, not hummus!

What is Humus?

Before I define humus, let’s look at some similar terms that add confusion to the story.

Humus Layer

This term is used to describe an upper level of soil – that dark black layer, such as in “that humusy layer of soil’. Although the dark color is probably due to humus, humus is not a layer in soil. There is no such thing as a ‘humus layer’.

Humus Soil

This term is floated around the net and it is not clear what it means. Is it soil with humus in it? Most soil has some humus so why not just call it soil? It is a term that should not be used.

Humus = Compost

In agriculture and gardening the term humus is sometimes used to describe well aged compost. You can buy bags of stuff labeled ‘humus’ at gardening centers, but this is just mislabeled compost. This is an incorrect use of the term. Compost is plant material that is slightly decomposed. Even aged, well-rotted compost is still only slightly decomposed. Have a look at this post for more on this topic; Compost – What is Compost. Once added to your garden compost will continue to decompose for several years. Compost is NOT humus.

Fulvic acid, Humic acid and Humin

These are terms referring to different sub-parts of humus. They have specific scientific definitions and should not be used in place of the word humus. From the point of view of gardeners these terms should not be used.

Humification – The Process of Creating Humus

The best way to understand humus is to understand how it is formed. Dead plant and animal material consists of organic matter. Organic matter is a catch all phrase used to describe a wide range of molecules including starches, proteins, sugars, carbohydrates, amino acids etc. When organic matter starts to decompose these molecules are broken down into smaller and smaller molecules by the micro-organisms in the soil (mostly bacteria and fungi). This is a complex process and the gardener does not need to understand the details of the process. What is important is that most of the useable chemicals in the organic matter are extracted by the micro-organisms and are eventually made available to plants.

At some point, all of the good stuff in the organic matter is used up and some molecules remain that can’t be used by micro-organisms or plants. This remaining material is called humus. It consists mostly of carbon and so it is still organic, but micro-organisms just can’t decompose it any further. Humus is so stable that it can persist in the soil for hundreds of years.

Humus consists of very large complex carbon based molecules. More recent research suggests that it might actually consist of smaller molecules that are conglomerated into large complex systems. Scientists still don’t understand humus completely.

Humus is very important for your garden – I’ll explain why in the rest of this post. The gardeners job is to increase the amount of humus in soil.

Humus – The Secret to Great Soil

Think of humus as being a big sponge that can hold up to 90% of it’s weight in water. This water holding capacity of humus is why humus rich soil will remain moist for weeks longer than soil without humus.

Humus has a negative charge which means that many of the nutrients plants require stick to humus, including ammonium (source of nitrogen), calcium, magnesium and phosphorous to name a few. The humus sponge holds onto these nutrients and prevents rain from washing them away. When a plant root comes in contact with it, the plant root is able to remove the nutrients from the humus sponge. The process is a bit more complicated than this, but you can think of humus as being a slow release source of fertilizer for your plants.

Perhaps the most important reason for having humus is that it is responsible for aggregation. Aggregation is what makes soil loose and very friable, improving the structure of soil. Better soil structure found in humus rich soil makes it easier for plant roots to grow by providing them with better access to nutrients, water and most importantly oxygen.

How do You Increase Humus?

Humus is left after organic matter decomposes. Each time you add organic matter to the soil, it will increase the amount of humus in the soil. It is a slow process but if organic matter is added each year, the amount of humus will continue to increase.

You can use any type of organic matter. I believe that the best organic matter to use is the one that costs the least. This is not strictly true, but a low cost usually means that the material has not been overly processed and it has been trucked a shorter distance. Both of these are good for the environment. Use the material that is locally available.

Manure, compost and wood chips are great choices. Just add your organic matter as a mulch and let nature incorporate it into the soil. Never rototill or dig it into the soil since this practice destroys soil structure.

As far as I know you can’t buy humus. Every product that I have looked that calls itself humus, is just some form of compost. I guess someone might be able to buy soil from a forest that has been in place for 100 years. That soil will certainly contain humus–but it is not just humus.

Can You Have Too Much Humus?

Healthy soils contain 2.5 to 5% organic matter, by weight (5 -10% by volume). This number does not include the humus amount. Too much organic matter can be a problem for soils so adding huge amounts of organic matter in order to build humus quickly is not a good idea.

In gardens like shrub boarders and flower beds where you are not harvesting crops, a small annual addition of organic matter, say a 2″ layer, is all that is required. In vegetable gardens where you are harvesting crops and taking nutrients away from the garden, you can add a bit more but not huge amounts. You can add too much organic matter which will cause all kinds of problems.

I have not really answered the question–can you have too much humus? I am not sure. Since humus is created very slowly, I would not be too concerned about having too much.

Does Humus Exist?

This section was added March 2016.

I wrote the above in 2013, and at the time it was the latest information available. In December of 2015, a new study was published that drastically changes our understanding of humus. It concludes that humus does not really exist. Humus is created when soil is treated with a pH solution, but it never occurs in soil.

For a detailed review of this finding, have a look at Humus Does Not Exist – Says a New Study.

1) Photo Source: Middle East Delights

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Why are limes alkaline, but lemons are acidic? They taste about the same [closed]

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What are the health benefits of lemons vs. limes?

Share on PinterestLemons and limes contain lots of vitamin C, flavonoids, and antioxidants.

Both lemons and limes have a long history of use in traditional medicine. They each contain antioxidants, vitamins, and minerals and provide a range of health benefits.

People also make claims about the health benefits of lemon water and the potential benefits of drinking lime juice.

Lemons and limes have several shared health benefits because they share the following properties:

They contain lots of vitamin C

Both lemons and limes are high in vitamin C, an important antioxidant that helps protect cells from damage.

Vitamin C also helps the body absorb iron from foods and supports the immune system.

The body also uses vitamin C in the production of collagen, an important substance for healing wounds.

They contain flavonoids

Lemons and limes both contain flavonoids. Flavonoids are phytochemicals that may have several health benefits, such as for heart disease and metabolic disorders.

Animal and cell studies have suggested that flavonoids have anti-inflammatory, antidiabetic, cancer-fighting, and neuroprotective properties. However, more research is needed to fully understand their effects in humans.

Research into flavonoids is still in its early stages, but the initial findings are promising.

They contain antioxidants

Along with vitamin C, lemons and limes also contain other antioxidants.

Antioxidants help protect the body from cell damage, which appears to play a role in a range of chronic health conditions, such as diabetes, cancer, and dementia.

It is possible that antioxidants also help prevent these conditions from developing. However, again, research into this area is ongoing.

They may aid weight loss over time

Some sources claim that consuming lemon, or lemon-based products, can help with weight loss. For example, lemon water is a mixture of fresh lemon juice and water and is a part of some weight loss diets.

However, there is currently no scientific evidence to prove that lemon, or any lemon-based product, can result in weight loss above what adequate hydration promotes. Learn more about the lemon detox diet here.

Lemons can form part of a healthful diet that eventually leads to weight loss, but this is likely to be as a result of a reduced calorie intake, regular exercise, and other more substantial lifestyle improvements.

Orange juice is acidic. Toothpaste commercials might have you believe that’s a bad thing (with their worrisome fears of acid erosion to sell high end toothpastes), but in the grand scheme of things, you really WANT the acidity that can only be found in citrus juices. Orange juice alkalizes your body.

I am not a medical professional. I’ve just done a lot of personal research on the acid and alkaline effects in your body. Please consult your physician for medical advice for your specific needs.

Acid or Alkaline Effect In Your Body

When citrus, such as oranges, lemons, limes and tangerines, enter your body and are broken down and metabolized, it creates an alkaline effect.

If you remember anything from high school chemistry, you might remember that acid and alkaline are very different from each other.

So the transformation of orange juice and other citrus fruits in your body from acid to alkaline is really, really cool.

Why should you care? Your body is healthier in an alkaline state and some research suggests that cancer cells actually can’t survive in high alkaline environments and bones are healthier in an alkaline environment.

Have I got your attention now?

Your body wants an alkaline environment to work properly. However, our modern American diet – high in animal proteins, dairy, added sugars and processed foods – produces an acidic effect inside your body. That’s not good.

  • Tangerine Cocktails and Mocktails
  • What are Flavor Packs in Orange Juice?

An acidic environment inside your body (keep in mind – this has nothing to do with the acidity of foods before you consume them) keeps your body from working properly.

The more acidic your insides are, the harder your body has to fight to stay healthy. That doesn’t seem fair, huh?

With too much acidity, your body can’t absorb as much minerals and nutrients, or produce energy in cells (and don’t we all need some more energy?). Your cells can’t repair themselves as well.

Even more scary, tumor cells thrive in acid environments inside your body – and no one wants that.

A lot of factors affect the very delicate acid to alkaline ratio inside your body. To recap chemistry class, pH neutral is 7.0. Anything over that is alkaline. Anything less than that is acidic.

*Did you know that you can check your body’s acidity or alkaline level at any time? Use these pH test strips to test your saliva or urine to see what’s going on inside.*

Food has a MAJOR impact on whether or not your body is acidic or alkaline. To be fair, emotional stress and toxic overloads can spin your body into an acidic environment, too. So you want to consume foods that will have an alkalizing effect on your body, even if you think you eat right already.

Citrus Fruits Alkaline Your Body

Citrus fruits with their high acidity actually alkalize your body. So drinking lemon juice, orange juice, tangerine juice and other fruits that remind you of sunny days can bring down the acid balance inside and start to put your body into a healthier pH balance.

You want only pure citrus juice though, without any added sugars, flavors or preservatives. And skip orange juice made with flavor packs, too. (Read to see what flavor packs are.) Organic is always best, too, in order to reduce your exposure to toxic chemicals, which could raise the acid count in your body.

Lemon juice is among the strongest alkalizing fruits available. Just behind lemons, though, are mango, guavas, nectarines and oranges. Beets and apples are moderately alkaline, too.

Let’s make it clear, though. As great as consuming orange juice can be for your health, the acid can still wreck havoc on your tooth enamel.

Hear are the quick fixes for reducing acid erosion on your teeth from citrus juice:

  • Brush your teeth after drinking citrus juices
  • Drink through a straw
  • At the very minimum – swish water around your mouth after consuming citrus foods

Facts about Chalk

  • Chalk is a natural fine-grained limestone that was formed slowly as a deposit in water greater than 150 feet (50 meters) deep.
  • The fine-grain particles in natural chalk are typically the remains of tiny marine organisms.
  • Natural chalk is found throughout the world. Large chalk deposits are found in the Cliffs of Dover, the North Atlantic Ocean, Texas, the Gulf coast and the North Sea.
  • Chalk is used to make portland cement and lime for fertilizer or manufacturing. Natural chalk and manufactured chalk has been used since the 1800s in the classroom.

Other Uses for Chalk

  • Other uses for chalk include gymnasts, weight lifters, rock climbers and other athletes use chalk to keep their hands dry.
  • Athletes use chalk to keep their hands dry.

  • Sports such as soccer, baseball, football and even tennis have used chalk to mark the sports fields or courts.
  • Chalk is used as an abasive in cleaners.
  • Chalk is used to raise the pH of soil.
  • Chalk is used by the police as a fingerprint powder to detect fingerprints.
  • Chalk was previously used in the classroom for chalk. Now calcium carbonate mixtures are used for classroom chalk instead of natural chalk.


Chalk, soft, fine-grained, easily pulverized, white-to-grayish variety of limestone. Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite. The sponge spicules, diatom and radiolarian tests (shells), detrital grains of quartz, and chert nodules (flint) found in chalk contribute small amounts of silica to its composition. Small proportions of clay minerals, glauconite, and calcium phosphate also are present.

Extensive chalk deposits date from the Cretaceous Period (145.5 million to 65.5 million years ago), the name of which is derived from the Latin word (creta) for chalk. Such deposits occur in western Europe south of Sweden and in England, notably in the chalk cliffs of Dover along the English Channel. Other extensive deposits occur in the United States from South Dakota south to Texas and eastward to Alabama.

Like any other high-purity limestone, chalk is used for making lime and portland cement and as a fertilizer. Finely ground and purified chalk is known as whiting and is used as a filler, extender, or pigment in a wide variety of materials, including ceramics, putty, cosmetics, crayons, plastics, rubber, paper, paints, and linoleum. The chief use for chalk whiting, however, is in making putty, for which its plasticity, oil absorption, and aging qualities are well suited. The chalk commonly used in classrooms is a manufactured substance rather than natural chalk.

Top 10 Unusual Facts Involving Chalk

When marine creatures die, their shells turn into a sludge consisting mainly of calcium carbonate. This goo eventually turns into the limestone known as chalk. The stone is responsible for several scientific discoveries, but the best facts are those that are weird and wonderful.

From chalk cliffs holding particles from outer space to an unexpected wonderland under the sea, the natural side of this rock hits spectacular highs. Ancient humans also left their mark with mysterious chalk artifacts. Today, criminals and cops alike love their chalk pencils and not in a way that people appreciate.

10 Bat Migration Discoveries

Photo credit:

Researchers know plenty about bird migration. However, the science is a bit lacking about arduous journeys made by mammals, including bats. An important first step is to find out which direction the animal takes flight. With birds, researchers usually confine them to an enclosed, small box before release. However, bats just keel over and sleep in such spaces.

In 2017, a German scientist took a simple round box. He covered the top with a lid but left enough space for the bat to crawl up the side and escape. The bottom of the circular device was sprinkled with chalk.

The bat crawled through the powder, leaving a trail that showed the direction it chose. After 54 bats crawled out of the funnel, it revealed that adults kept flying in the direction they picked upon takeoff.

Other tests proved that the sunset helped them to navigate. When confused by reflections of real sunsets, they took off after the pseudo dusk. Juveniles appeared clueless and set off in random directions. This suggested that young bats must learn how to navigate from more experienced elders.

9 Mysterious Bowl Fragment

Photo credit: Live Science

In 2015, a discovery happened in Jerusalem. For the most part, it was not mysterious. The artifact was a fragment of a chalk bowl made 2,100 years ago. But for experts obsessed with names and neat answers, the shard caused confusion that would last a long time.

The chalk bore the name “Hyrcanus.” The Greek name was carved in Hebrew letters, an echo of the Jewish preference for the name during this time. Indeed, two different kings from the Jewish Hasmonean dynasty (140 BC to 37 BC) were called Hyrcanus.

Therein lies the scholarly head-scratching. Did the bowl belong to a commoner or a king?

There seems to be no right answer. The location of the shard was no help at all but nevertheless interesting. It was found under the Givati parking lot in Jerusalem’s most ancient neighborhood. This is fitting as the fragment is among the oldest examples of its kind found inside the city.

Later, chalk vessels became widely used. But so few date from the fragment’s time that researchers cannot say whether the name-inscribed object was commonplace or commissioned.

8 The Fulltouch Panic

In Japan, the Hagoromo Stationery company produced blackboard chalk called Fulltouch. As in, past tense. This sent a flurry of anxiety through academics who could not imagine writing with any other brand.

Most people have written with chalk and experienced the annoying sudden breaks and sticks that refuse to write while causing more dust than a sandstorm. Fulltouch crayons shed no dust. Despite being hard enough to never snap, the chalk wrote like a dream—smooth, bright, and easy to see even by students in the back row. Best of all, the sticks were long-lasting.

In 2015, the news of the factory’s shutdown caused some scholars to stockpile enough boxes to last them 15 years. Others delivered tributes online as if they had just lost a close friend. The panic was a bit premature. Hagoromo sold the Fulltouch recipe to a Korean company, and the finest chalk in the world is available once more.

7 Fossil Dust

Photo credit:

In 2017, chalk gave scientists the chance to learn more about the solar system’s history. It began with the chalk cliffs in Dover, England, which contain tiny fossilized creatures.

Studying the critters has already revealed a lot about Earth’s turbulent geological past. During one such study, researchers unexpectedly discovered that the cliffs also contained fossilized cosmic dust. The dust (aka micrometeorites) was highly sought-after but nearly impossible to find even though 22,000 to 33,000 tons flutters down from space to Earth every year.

The problem? The particles are microscopic, and fossilization changes their known minerals to the point of obscurity. But the 76 particles found in Dover were exceptionally well-preserved. Their good looks provided the new criteria by which to find micrometeorites.

Similar to animal fossils, the composition of micrometeorites could reveal more about space events in the past. For example, the 87-million-year-old dust could have been formed by asteroids colliding with each other or the planets.

6 Illegal Cop Doodles

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In 2019, Alison Taylor got another parking ticket. This time, she did not take it lying down. What angered the Michigan resident was not just the $15 fine but that police had doodled on her car’s tires—again.

The parking area in Saginaw had a two-hour limit, and cops used chalk marks to track the time. Taylor’s lawsuit went to federal court. The court system was not kind to the police department.

The judge agreed that the practice was unconstitutional because the marks already tagged a driver for an offense not yet committed. Even those who left the parking lot before the two-hour limit drove off with chalked wheels.

The case went to the appeals court where a three-judge panel proved even more critical. They deemed that tire marking existed to primarily raise money and not to keep people safe. Indeed, Saginaw raked in almost $200,000 every year thanks to chalk-wielding police officers. The court’s ruling against this “fund-raiser” covered Michigan, Kentucky, Ohio, and Tennessee.

5 Oxfordshire’s Burial Pits

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Human history is densely concentrated on the British Isles. To protect this ancient heritage, all construction projects must be preceded by an archaeological investigation to clear the land.

In 2019, Thames Water planned to install a pipeline in Oxfordshire. It was part of a conservation project to save Letcombe Brook, a rare chalk stream. While the chalk did not have much to do with the story in this case, its preservation led to something remarkable.

Thames Water followed the law and performed an archaeological survey when they found 26 human skeletons. The nature of the burial pits suggested that the funerals—or deaths—happened in a ritualistic manner that likely included sacrifice.

The 3,000-year-old group had their body parts moved around. Heads were found near feet, and some had amputated feet flanking the torso. As excavations continued, the team found animal remains, signs of homes, and several domestic items.

The artifacts could reveal unknown information about the Iron Age Britons of the time. Not a lot is known about them. But seeing that they created the monumental Uffington White Horse, their culture is worth studying.

4 The Folkton Drums

Photo credit: Live Science

Over 4,000 years ago in Britain, somebody carved three objects. Made of chalk, they resembled drums with decorations. The set was buried with a child and rediscovered in 1889 near Folkton in Yorkshire.

These were no ordinary grave goods. Despite the different sizes—ranging between 10.4 centimeters (4.09 in) and 14.6 centimeters (5.75 in) across—the cylinders had one thing in common. When researchers wound a string around each, a certain measurement arose at one point: 10 “long feet.”

Today, a long foot would equal 32.2 centimeters (12.7 in). Back in the day, 10 was the standard used to build henge monuments. The most famous was Stonehenge. The unique artifacts were joined by another chalk drum a century later.

Found near England’s south coast, the so-called Lavant drum was also hand-sized and provided 10 long feet when a string was wrapped around it nine times. (The others had to be wrapped 7–10 times.)

Nobody knows why the different sizes were necessary when the cylinders all did the same thing. However, as chalk is not the smartest material choice for builders’ tools, the artifacts were certainly replicas of the real thing. The originals were probably wooden.

3 The Longest Chalk Reef

Photo credit: The Telegraph

In 2010, divers sought funding from the Norfolk County Council. The group of friends knew there was a chalk area off the coast, although they suspected that it was small.

Even so, this suspicion included the presence of a chalk reef they estimated to be around 8 kilometers (5 mi) long. This was a baby compared to the Thanet Coast chalk reefs found in Kent, which were the longest in the world at 22.5 kilometers (14 mi).

The county council never regretted doling out the funding for the Norfolk expedition because the divers’ discovery dwarfed the Thanet reefs. The unexpected wonder ran for 32 kilometers (20 mi).

The stretch of bright white stunned researchers with its complex arches, many as high as a person and appearing in rows in some places. It had gullies and moonscapes but also an abundance of life.

The 300-million-year-old reef had plants, wildlife, and fish, including several species never recorded in the region. Among them was a type of sponge seen for the first time.

2 Chalky Sea Swirls

Photo credit: Live Science

There are swirls so huge that they cover 16 percent of Earth’s seas and can be seen from space. Called the Great Calcite Belt, its size is only transcended by its ethereal beauty. The swirls shimmer with a milky turquoise iridescence.

Found in the Southern Ocean, the giant phenomenon is ironically the result of microscopic organisms. Phytoplankton called coccolithophores are truly small. Each is a single-celled creature that is neither bacterium nor plant. But once in a while, their numbers bloom to epic proportions.

The milky hue of the bloom’s swirls is caused by chalk. To protect themselves as they grow, coccolithophores plate themselves with layers of chalk. When they crowd together, the vast number of chalky bodies reflect light into the sky and create the spectacular hues.

1 Gang Chalk Symbols

Photo credit: The Telegraph

Around 65 dogs are stolen every day in the United Kingdom. In recent times, these sophisticated gangs appeared to have adopted an open symbolic language to communicate with each other—at the scene of the future crime.

Drawn in chalk, the marks appear on pavements, walls, or roads close to the dogs’ homes. Thieves abduct popular breeds as well as trained working dogs. However, it is feared that a large number are stolen for dog fighting—either to fight themselves or to be killed by larger dogs as bait.

The symbols most recently appeared in County Durham and Darlington where there was a spate of pet disappearances.

Another line of symbols, known as the Da Pinchi Code, appears to mark human victims. They are mostly made of circles, rectangles, lines, and crosses. While their exact meanings remain unknown, some are believed to mark security systems, vulnerable women, wealthy homes, and risky targets.

Read more fascinating facts about rocks on Top 10 Rocks That Stink and 10 Most Deadly Rocks and Minerals.

Jana Louise Smit

Jana earns her beans as a freelance writer and author. She wrote one book on a dare and hundreds of articles. Jana loves hunting down bizarre facts of science, nature and the human mind.

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Chalk and Clay


Formed 70 to 100 million years ago, chalk is also called cretaceous limestone.It is a soft, white rock.

Chalk is an example of a porous rock, as it has pore spaces, which can store water. It does not have joints and bedding planes like carboniferous limestone.


Is a product of chemical weathering and river erosion.

Clay is porous, but becomes impermeable when wet, as the particles expand and fill the pore spaces.

The main areas of chalk and clay in this country are in the South and East of the country. Places like the North and South Downs are good examples.

  • Bournes are streams that occasionally flow down the dry valleys in times of prolonged wet weather, when the ground may have become saturated.
  • Clay vales are the valleys between the chalk escarpments. The clay, when drained is a fertile soil suitable for a range of farming methods. Clay vales are flat, and have a number of streams meandering through them.
  • Dry valleys, such as Devil’s Dyke, were formed in periglacial times, when the ground froze, so melt water rivers ran over the surface of the chalk rather than flowing down through it. These rivers carved out steep sided valleys. Once the climate had warmed again a dry valley was left behind. These also are common features of limestone landscapes.
  • Escarpments or cuesta’s are the main landform of chalk and clay areas. Initially the layers of chalk and clay were tilted by the collision of the African and Eurasion plates. The soft clay was then eroded faster than the more resistant chalk, leaving escarpments (chalk hills) behind. Because of the angle of the tilt, these escarpments have two distinctive sides. The steeper side is called the scarp slope, whilst the gently sloping side is called the dip slope.

    Springs form at the bottom of the escarpment, where the chalk meets the clay. This is why many settlements can be found along spring lines in chalk and clay areas.

Clay is very fertile, but must be drained first. Once that has been done farming includes dairying, sheep grazing, and some arable farming. On the chalk escarpments the main agriculture is sheep grazing.

Many settlements were built at the bottom of the scarp or dip slope, as the land was less likely to flood, there was a good water supply, and there was good farming land nearby. Very early settlements would have been higher up the chalk escarpment for defensive purposes.

Chalk is a main ingredient in cement making, and is quarried for that purpose. Clay can be used in pottery.

Underground aquifers act as a store for water within the chalk and are used as a natural water supply for London.

Like any other compound, chalk has its own special scientific name. It is called “Calcium Carbonate.” It is represented in the formula “2+ + 2- = CaCO3.” The equation “CaCO3” means that there is one carbonate ion which is made of one carbon atom and three oxygen atoms and one calcium atom and so they attract each other since they have opposite charges and form a compound to become stable. Like many other substances chalk has its very own unique physical characteristics. (Ed. K. Lee Lerner and Brenda Wilmoth Lerner,”Calcium Carbonate”,2004)
Chalk consists of variety of special physical properties, which are the following:

  • White (Can change due to additional impurities)
  • Smooth
  • Porous
  • Powdery
  • Brittle
  • Fairly easy to break
  • Opaque
  • Dull
  • Not malleable
  • Not ductile
  • Doesn’t conduct electricity

Some of its special chemical properties are:

  • Decomposes into CO2 (Carbon Dioxide) and CaO (Calcium Oxide) instead of melting
  • It reacts with strong acids, releasing carbon dioxide
  • It releases carbon dioxide on heating (to above 840 °C in the case of CaCO3), to form calcium oxide, commonly called quicklime
  • Calcium carbonate will react with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate. (Princeton University “Calcium carbonate.” (n.d.))

Calcium Carbonate is also commonly known as limestone, calcite and aragonite. Chalk is also known as magnesium silicate (French powder chalk) and calcium sulfate (Sidewalk Chalk). (N. Schlager, J. Weisblatt, & D. E. Newton, “Calcium Carbonate”,2006)

Factors controlling fracture characteristics in Chalk Formations in the Dutch Offshore


Factors controlling fracture characteristics in Chalk Formations in the Dutch Offshore: Results from a study based on Seismic Attributes


Nederveen, Ruud (TU Delft Civil Engineering and Geosciences; TU Delft Geoscience and Engineering)


Bertotti, Giovanni (mentor)

Degree granting institution

Delft University of Technology

Date Abstract

Faults can both improve producibility and fluid flow in hydrocarbon reservoirs, and cause leakage and instabilities in sealing layers. For this reason it is of importance to create a multiscale understanding of the drivers behind deformation, and how deformation is accommodated. Carbonates have always been of interest to the oil and gas industry as carbonates house some of the world’s largest oil and gas reserves. Understanding, and maybe predicting the geometries and fracture types could therefore be of integral importance to the E&P industry. For that reason two seismic datasets were provided for analysis on both a Fault Network Scale (faults over >1km in length) and a Small Seismic Scale (faults <1km in length). For the Fault Network Scale Petrel was used for seismic interpretation of the faults, as only the largest faults were interpreted in both seismic datasets. For the Small Seismic Scale OpendTect was used for enhanced seismic interpretation. OpendTect’s fracture enhancing attributes and filters provide seismic images with a high level of detail. These attributes were applied to 5 generated steering-cubes, to display even the smallest faults. The results on the Fault Network Scale show that most faults are caused by regional tectonics. However in areas where salt is underlying the chalks of the Chalk Group, halokinesis is the main driver of deformation. On the Small Seismic Scale drivers behind deformation differ more, fluid expulsion drives polygonal faulting patterns in areas where salt tectonics or far field extensional tectonics are absent. Towards halokinesis structures salt tectonics will be the main driver behind deformation. In areas where salt is absent, far field tectonics can still influence chalks forming fractures either parallel or perpendicular to the major surrounding faults.



To reference this document use: Part of collection

Student theses

Document type

master thesis


© 2018 Ruud Nederveen

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