How do Rivers Form?


A cross marking the source of the Amazon, the greatest river on Earth

Rivers begin life as a trickle of water that originates high on a hillside or in a mountain range. Most of these thin runs of water, known as headwaters, emerge through the earth from underground streams. These submerged bodies of water are formed when rain or snow seeps into the ground, before the pressure of being trapped underground bubbles it back to the surface. This water is called surface run-off.

The course of a fledgling river’s surface run-off is steered by gravity, which will initially send the water flowing downhill in trickles, which will eventually meet with other parallel rills or tributaries, as it gathers momentum. Once these parallel rills unite, they form a stream. When more rills converge with the stream, a bigger flow of water is formed; a brook.

Guided by gravity and the surrounding geology, the brook flows on through the valley, its volume of water swelling with rain and groundwater. The brook becomes wider as it travels, and as its water level rises, it becomes a river.

It isn’t the weight of the moving water alone that dictates how wide or deep a new river is to become. It is the river’s load which will gorge out its path in the geology that surrounds it. A river’s load will include any rocks, stones, and other large particles, which wash along the new riverbed. As the river water pushes its load along, the bed of the river will deepen.

The speed of the moving water determines how quickly the load will erode the river’s banks, and how wide the river will become. As the river winds through the landscape, it carves out deep valleys in solid rock and deposits huge amounts of debris on either side of it.

Not all springs, brooks and streams that form into headwaters on high ground will become rivers. Many will remain small creeks, brooks, rivulets or tributaries. Those that do become rivers will forge their way through the geology of the earth until they reach, and sometimes merge with, other rivers, and then ultimately meet the sea.

512px-Hawaii_Volcanoes_NP_MagmaThe Earth’s crust is made up of huge slabs called plates. These massive plates fit together rather like a jigsaw puzzle. Sometimes these plates move, and the friction that action causes, can lead to both earthquakes and volcanic eruptions.

A volcanic eruption occurs when the pressure and high temperatures beneath the plates cause rocks to melt. This melted rock turns into a liquid known as magma (or molten rock), which seeps through the Earth’s crust, before gradually making its way up to the top of the volcanic mountain, and eventually form into rivers of magma that brim beneath a volcano’s surface.

The pressure in this magma chamber fills and builds, like water and steam in a boiling kettle. It is when this pressure reaches breaking point that the eruption occurs. Gases and rock shoot up through the opening in the top of the mountain, spilling over its edge. The moment magma reaches the top of the volcano it becomes lava, which flows down the sides of the volcano.

The lava flows are only part of the devastating effects of a magma explosion. As the air around the volcano blast fills with lava fragments, hot ash adds to the lava flow, as well as sparking mudslides, avalanches, falling ash and floods.

The most powerful volcanoes release a pyroclastic flow. This is a fluid mixture of solid to semi-solid boiling hot fragments that include expanding gases, which cascades down the sides of a volcano. Volcano eruptions can also trigger tsunamis, flash floods, earthquakes, and rock falls.

There are three recognised stages of volcanic action. They are either active, dormant, and extinct. An active volcano is one which has recently erupted and there is a possibility that it may erupt soon. A dormant volcano has not erupted in a long time, but there is a possibility it might erupt in the future. An extinct volcano is one which has erupted thousands of years ago and will never erupt again.

There are more than 1500 active volcanoes on the Earth. Another 80 have been discovered under the ocean, and there are believed to many more hidden beneath its waves. The world’s largest, active volcano is Mauna Loa in Hawaii. It is 13,677 feet above sea level, and from its base below sea level to its summit, Mauna Loa is taller than Mount Everest.

5.4.13_Ljubljana_15_(8623814958)The United Kingdom is well known for its heavy rainfall, but what causes it to rain in the first place?

Rain occurs when warm, moist air cools down, creating condensation, or vapour. This water vapour originates from rivers, lakes and the sea, and rises into the air to form clouds of water or ice crystals. As the clouds rise higher, the air surrounding them gets colder, until eventually the cloud becomes too heavy, and the water vapour falls back to the ground as rain or even snow.

Although rain always forms in the same manner, it can be categorised into three different types – orographic rain, frontal rain, and convective rain.

Orographic rain is only produced over mountainous areas close to prevailing westerly winds, when moist air from high ground is forced upwards, producing clouds.
The geography of the UK means that this type of rainfall is most common in the north and west, and is one of the main causes of rain in the wettest part of the UK, the western Highlands in Scotland, where they receive three metres of rainfall every year.

Frontal rain occurs when a mass of warm air meets a mass of cold air. As the two masses have different densities they can’t mix together, so the less dense, warmer air is pushed up and over the cold, dense air. This creates a weather front which condenses the water vapour into raindrops. This type of rain is not subject to geographical factors, and can happen anywhere across the UK.

The final type of rain, convective rain, is most common in the warmer climate of the south and east of the UK. Convective rain is produced by clouds that are formed in vertical motions caused by the instability of the atmosphere. This instability is caused by heat from the sun warming the ground, and moisture from that ground evapourating and rising. At the same time as this, the hot ground also heats the air above it. This additional water vapour rises as well, cooling and condensing into clouds before turning to rain.

The flooding that has been so severe in the UK in recent years was caused by all three of these types of rain occurring at the same time.

Hopefully we shall not see too much rain in the next couple of months, but from past experience, that may not be too likely…

What initial conclusions about the future of GCSE exams can we draw from the mountain of documents which Michael Gove and the Department for Education released last week? And who will the winners and losers be if these proposals come to pass in their current form?

There is no doubt that the new exams will be harder and more “academic”. If not a return to the degree of difficulty posed by the old O-level exams, these new outline specifications match the difficulty and depth of the current IGCSE (International GCSE) specifications set by Edexcel and the Cambridge board. The message seems to have been: take the best of the current IGCSE specs and call it a GCSE instead.

The subject advisers seem to have taken this brief quite literally in most of the core subjects. It is perhaps most clearly seen in Mathematics, a subject in which the IGCSE specifications already require a number of skills that have been beyond the scope of the GCSE Maths syllabuses for 25 years but which are fundamental to AS level Maths. These include function notation, kinematic problems, set notation, rates of change and Venn diagrams, to name but a small sample of topics. There they are in the new drafts in bold print. This is IGCSE Maths by another name.

Most topics are not in bold print, implying that the boundary between what is now the GCSE Foundation and the current GCSE Higher levels is set to shift. Vectors, formerly to be found in the GCSE Higher level requirements, appear in plain text here, including the multiplication of vectors by a scalar. Some maths teachers may need to go on a refresher course to master the required skills!

Similar principles underlie the Science draft. Not only will the individual specifications require considerably more depth of study, as they do in today’s IGCSEs, but the Combined Science qualification will be the equivalent of two GCSEs, not one, just as it is today with IGCSE Science but not GCSE Science. The simple principle behind GCSE Science is to take one-third of the Biology specification, one-third of the Chemistry and one-third of the Physics, while IGCSE takes two-thirds of each of the respective individual subject specifications. The new proposals unashamedly mimic the IGCSE formula.

If this means that all candidates will now face a choice between tackling the new Double Science GCSE or leaving school without any formal recognition of their achievements in the sciences, there will be huge numbers of schoolchildren who fall in the latter category. While the old “everybody passes” philosophy of GCSE had its disadvantages, do we really want to stigmatise a whole generation as incapable of taking and passing the “simplest” of the new science specifications?


Children who are educated at home are unfairly denied access to examinations, according to a report in today’s Daily Telegraph.

This is not really a new story. Some home-schooled candidates have always found it time-consuming and awkward to locate suitable exam centres to take their exams for GCSE or A-level. But the Commons Education Committee has now said that it is “not reasonable” that some young people are struggling to sit national tests. It calls for a duty to be placed on councils to provide access to examination centres.  It also asks for examinaton fees to be met from public funds. We are happy to endorse all those proposals!

As Graham Stuart, the Committee’s Chairman, says: “Everyone else gets to take GCSEs and home-educated children should do so [for free] as well.”

These are welcome sentiments and time will tell whether they lead to genuine change. But they ignore the more fundamental problems of GCSE examination entry for the home-schooled, namely the need for all candidates to produce controlled assessments (coursework) in most of the main subjects, including English, History, Geography, languages and all the science subjects. Controlled assessment (as the government has defined it) is not possible for home-learners on distance learning programmes like the ones we offer, so, whether the costs are met or not, our students simply cannot take GCSE exams in these subjects.

Four years ago, Oxford Home Schooling fought hard to preserve GCSEs which were genuinely accessible to home learners, but the government rejected all our pleas. As a result, most of our students now take International GCSEs (IGCSEs) rather than GCSEs, an equally valid alternative but confusing for many families. And now those IGCSEs must call themselves “certificates”, not GCSEs, which also leads to marginalisation and confusion.

There are moves afoot to re-introduce exams (at age 16) which do not require controlled assessment, possibly based on the current IGCSEs, and such a development would be welcome news to thousands of home learners and their families.

The government, via OfQual, has invited all interested parties to make comments on the proposed changes to the GCSE system. I think it is in all of our interests to make our views known, even if those views are completely ignored as they were last time around!

While the move away from modular exams is a positive development for anyone involved in home schooling there are problems afoot which will affect future students, if not those who are thinking of embarking on GCSE courses at the moment.

In my view, the proposed changes fail to address the single biggest problem with qualifications at this level – the difficulty of taking the exams for anyone outside the mainstream school system.

The rules for controlled assessment make it difficult or impossible for “irregular” students (including adult learners and the home-schooled) to enter for exams at all. Such students cannot satisfy the requirements for supervision and other aspects of “control”. In English (and other key subjects like Science, History and Geography), there are no GCSE specifications at all which dispense with the need for controlled assessment, because exam boards are not allowed to set such specifications in those subjects – I am sure they would like to!

The result is that home-schooled students are currently obliged to take IGCSE courses in those subjects, but that option will become  fraught with problems after 2014. Meanwhile, IGCSE is a title that will no longer be used in the UK where IGCSEs are being replaced with “Certificates” (as set by Edexcel and others) and in order for the Certificates to be accredited, a number of Certificate specifications, notably in English, must include coursework which itself is subject to stringent controls. In practical terms, this may well mean that examination centres will eventually be unable to allow entry to private candidates.

To take a typical example … any home-schooled child, between the ages of about 14 and 16, will expect to be able to take a GCSE-level qualification in English, Science and various other “core” subjects.  At the moment, it is possible to take an IGCSE instead, with no coursework, and so gain an equally prestigous and useful qualification.

In future, there may be no options available at all, or the ones that are left will be so fraught with controlled assessment and other logistical problems to the point where it is impossible for the private candidate to take the exams anywhere.  Do we really want to close down such options for a generation of home-schooled kids?

Several thousand home learners a year fall into this category and would be effectively excluded from the examination system.  This diverse group lacks a voice or effective representation but it is hugely unfair that it should be, in effect, excluded by this unfair one-size-fits-all policy.

There are a number of possible solutions, including the following:

  1. The government allows non-coursework GCSE specifications in subjects like English and History (just as they already do in such subjects as Maths and Psychology).
  2. The government allows non-coursework options within GCSE specifications, open to certain categories of candidate for whom controlled assessment is impossible or inappropriate.
  3. The government relaxes the controlled assessment rules so that coursework is once again practicable for home learners.
  4. The government accredits Certificates (or IGCSEs) that do not require coursework and ensures that success in such qualifications carries the same weight as success in the “regular” GCSEs, e.g. it secures access to 6th form courses and the like.

Option 4 is only a partial solution to the problem but a lot better than nothing. It is vital that one of these solutions is adopted now before the interests of many different categories of student are irreparably damaged.

The government has recently announced that there will be a number of changes to the GCSE system, affecting examinations in 2014 and later years.  What is going on?

The main change is that it will no longer be possible to sit GCSEs, module by module, over a series of exam sittings. This is called “unitisation”.  This will make a big difference to how subjects are taught in schools. At the moment, it s possible to master one part of a specification, take an examination in that, and then move on to the next part.  As a relatively small amount of information (or skills) need to be learnt at any given moment, the exam performance is inevitably going to be better – at least for those students and schools who “play the system” effectively. And if a grade for a particular module proves to be unsatisfactory, there is the option to re-take it at the next exam sitting. The final result is almost bound to be impressive.

That situation put distance learners and home-schoolers at a big disadvantage.  Most distance learners are only in a position to take the exam once, at the end, so they need to master the entire specification at a single moment in time. This has put them at a big disadvantage, competitively, with school-based students.  The new system will be fairer to all the different types of candidates – it should be as close to a level playing field as we can get.

The government has also promised that marks will be awarded for good spelling, punctuation and other aspects of correct English.  Most will agree that such skills are an important part of a rounded education and so this development is to be applauded.

The GCSE specifications are being reviewed by the examination boards in the light of these new guidelines and there is still time for some more fundamental changes to be made. Will a green light be given to the establishment of GCSE specifications which do not entail coursework and controlled assessment? Already there are some subjects like Maths, Psychology and Law, where no coursework is required and assessment if by final exam only – will that opportunity be extended to a range of other subjects, such as English, History and Geography where the GCSE specifications have to include coursework?

We would warmly welcome the establishment of such non-coursework GCSEs across the subject range because, again, this would eliminate one of the big disadvantages that distance learners and home schoolers currently suffer in certain subjects. Their coursework is marked by external examiners who (history has shown) do not mark coursework as generously as the teachers within schools who are assessing their own pupils.

The most ambitious schools have shown what they think of the current coursework arrangements by phasing in IGCSE exams as a replacement for GCSEs. IGCSEs (or Certificates as they are now called in the UK) are seen in certain cases as a fairer test of academic ability and potential. It is important that GCSEs should be seen as offering the same intellectual rigour.  With the move away from modular assessment, there is the opportunity for other significant advances in the testing of our 16-year-olds.

As Richard Garner has revealed in the Independent, more than 200 state secondary schools in the UK have ditched the GCSE in favour of IGCSE a more traditional O-level style examination.

Interest in International GCSEs has doubled over the past year since the Education Secretary, Michael Gove, gave schools the green light to offer it to pupils. In the past, schools could not apply for funding to put their pupils in for it and results could not be included in exam league tables. Now the funding is still not there for state secondary schools to offer IGCSE, but results are properly recognised within the state system and full credit given to successful candidates.

Because it is less reliant on government funding, most of the growth in IGCSE numbers in the UK has been in the independent sector where it is recognised that IGCSEs represent a more thorough preparation for A-level and academic studies beyond. Some of the IGCSE exams are a little bit tougher than the GCSE equivalents but this makes up for the fact that no coursework is involved. The absence of coursework and controlled assessment remains the single biggest advantage of IGCSE for those in home schooling and distance learners generally.

Graeme Paton notes in the Daily Telegraph that 945 schools offered IGCSE through Edexcel this year, compared with just 198 state schools offering the IGCSEs set by rival examination board, CIE (plus 350 private schools).  Why is Edexcel so popular? Its secret had been to offer specifications which are as close as possible to the GCSE equivalents so that they are recognisable to those who are used to the GCSE system, adding a little extra depth to compensate for the disappearance of coursework.

At Oxford Home Schooling, we offer a full range of courses for both GCSE and IGCSE so I have no reason to recommend one qualification over the other.  In many cases, it will depend on what subject the home learner wants to do and whether controlled assessment is a mandatory part of the GCSE specifications in that subject, as it is with such subjects as History, Geography and even English.  In such cases, there is little alternative but to opt for IGCSE instead. But students may be reassured that there are a vast number of exam cetres where they can sit IGCSE exams in the UK, especially with Edexcel, and that success at IGCSE will look at least as impressive on anyone’s CV and as equivalent success at GCSE.

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