Introduction
I like drumlins. Drumlins are cool 
. Every time I travel up the M6 beyond Forton services, there they are and despite the fact I've seen them lots of times, I never cease to enjoy looking at them and thinking about how old they are and the processes that formed them during the last ice age.
Once you've seen a drumlin and you know what they look like you'll probably notice them more and more - there are hundreds of them dotted about, and they are usually found in groups called swarms.
Ironically though, this EarthCache doesn't take you to a location where you can clearly see the whole drumlin and its overall shape. This EarthCache allows you to see something different - a slice through a drumlin, revealing its internal makeup!
Logging Tasks
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Based on your study of the exposed internals of the drumlin and using the information on the cache page please tell me:
- Which of the Wentworth grain sizes are present in the glacial till? (make sure you have a walk along the length of the exposed face to get a good look at the full range rather than just standing in one place).
- The slice through the drumlin has resulted from, at least in part, the erosive action of the sea. Describe any evidence here to suggest that erosion continues. (Hint: look up).
- Locate the scratched limestone boulder sitting on the grass at the edge of the shingle beach, close to the base of the drumlin, using the waypoint provided and describe the orientation / direction of the scratches made on its surface as it was dragged along by the glacial ice.
- Locate the volcanic tuff boulder a few metres to the south. It's easy to recognise as a) it's to the rear of a group of limestone boulders and b) it's a pale green colour in contrast to the white limestone. Does it bear the same sort of scratches as the earlier limestone boulder and if not, why not?
- Optional task: feel free to add any photographs of your visit that do not show the specific features from the logging tasks - no spoilers please. In the interests of allowing everyone to experience the EarthCache fully for themselves obvious spoiler photographs will be deleted.
Background
So what exactly is a drumlin anyway?
It's a slightly funny word which has nothing to do with drums. Nor are drumlins a family of white, round fairy tale characters with large snouts that make them resemble hippopotamuses - those are moomins 
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If you're a regular viewer of satellite TV programs aimed at kids - and especially the adverts between them - you could be forgiven for thinking drumlins are one of around a hundred different cheap plastic toy characters with cutesy names, designed to empty the pockets of harassed parents - but that's not true either .
A drumlin is actually a hill - specifically an oval shaped hill with some other defining characteristics. There are a couple of variations on the origin of the word but it seems to arise from the Irish / Gaelic word droimnin, meaning small ridge or littlest ridge. I can't help but wonder if the transition from droimnin to drumlin is the result of a mishearing of the Gaelic word (a mondegreen) or a misspelling arising while someone hearing the word spoken was documenting it.
What do drumlins look like and what are they made of?
They vary somewhat in terms of size and shape but the 'average' drumlin, if such a thing exists, has the basic characteristics shown in the cartoon diagram below:
So the average drumlin is usually a smooth looking, rounded, oval or egg-shaped hill - at least when viewed from above which, unless you've got a helicopter or a fancy, camera-equipped drone, you're unlikely to see.
Viewed from the side - which is much easier - a drumlin resembles an egg on its side, half buried in the ground.
Similarity to the standard egg shape does vary though - with shorter, wider variants, longer, thinner variants etc. etc.
Many drumlins are made entirely of boulder clay (more on that later) although some have a core of solid rock with a layer of boulder clay draped over the top . (I know - the boulder clay in the cartoon looks a bit like a delicious cake with a thin layer of green icing but trust me - you wouldn't want to eat it ).
Drumlins usually have a shorter, steeply sloping side known as the stoss side and a longer, more gently sloping side known as the lee side. The stoss side tends to be more curved / more blunt in comparison to the lee side which tends to look more tapered / pointy.
Drumlins can be as much as 100 metres high and a kilometre in length - but there are plenty of smaller ones too.
Oh yeah - as indicated in the diagram - the flow direction of the glacial ice which produces drumlins is from the stoss side to the lee side.
It's at this point that I realise that the process of explaining drumlins and the way that they're formed and what they're made of is a bit chicken-and-egg - if you'll pardon the pun . Imagine a chicken-shaped hill... that would be weird...
Glacial Ice and Boulder Clay
Today around 10% of our planet is covered in ice, but changes in climate in the past have seen seen this coverage rise to as much as 30%.
The Last Glacial Period (LGP) that affected the British isles began around 115,000 years ago, peaked around 29,000 years ago and ended roughly 11,500 years ago.
Scientists believe that the extent of glacial ice around 25,000 years ago was such that the whole of Ireland would have been covered in ice up to 1km thick. Scotland and most of northern England were also covered by deep glacial ice.
Once glacial ice exceeds a depth of 50 metres it starts to flow downhill under the force of gravity, picking up and carrying along clay and rock as it goes. The mass of clay and rock carried along by the glacier is known as boulder clay, although these days the term glacial till seems to be preferred.
This glacial till is what makes up much or even all of the body of the drumlin. As the glacial ice melts - either during seasonally warm weather or when the glacier eventually retreats substantially / completely, the till becomes saturated with water. In this saturated state the clay becomes sticky and, just like clay on a potter's wheel, capable of being moulded into and retaining particular shapes.
Grain Size
Glacial till is made up of clastic sediments with a variety of grain sizes, which are all jumbled up together quite randomly.
Geologists determine grain sizes in the field using printed cards called comparators, which usually have a millimeter scale, phi scale, and angularity chart. They are especially useful for larger sediment grains.
One scale of measurement commonly used to classify sediments / clasts / grains by size is the Wentworth scale, published in 1922 by Chester K. Wentworth. Wentworth's grades and sizes were later supplemented by William Krumbein's phi (from the greek letter φ) or logarithmic scale, which transforms the millimeter number by taking the negative of its logarithm in base 2 to yield simple whole numbers.
Here's a simplified version of the Wentworth scale, including the φ grades, which you can use to classify the clasts in the glacial till exposed in the slice through the drumlin.
How are drumlins formed?
The short answer is - nobody knows!
That's not to say though that we have absolutely no ideas about how drumlins are formed. There are a number of detailed hypotheses as to the processes involved - each of which has varying degrees of acceptance / support within the scientific community - but still nobody knows for sure.
Of course it may well be that none of the current hypotheses is correct - or that a number of them or some parts of them are correct but because drumlins are formed beneath glacial ice and the underside of a glacier is such an inaccessible environment, there's no telling when or even if we'll ever know for sure.
One hypothesis is that the glacial ice first recedes (shrinks back) - possibly due to seasonally warmer weather, dumping a load of saturated glacial till on the ground. At some later point - possibly with the return to colder weather with the onset of Winter, the glacial ice surges forwards again, sculpting and moulding the clay-rich glacial till into drumlin shapes.
In other hypotheses the drumlin formation is a single-step process occurring as the ice moves forward and still other hypotheses link the formation process to sediment-laden flood waters under the glacial ice filling up hollows previously scoured in the underside of the ice.
Perhaps we'll never know exactly how the drumlins we see today were formed - but it's definitely an interesting subject to ponder 
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If you've carefully read and digested the information from this cache page your tasks at the cache location should prove relatively straight forward, although you may wish to take a printed copy of the page with you so that you can check your answers while there .
Please submit your logging task responses before posting your log.