Sandy Hill, sits near the popular Ribblehead location. It is very well visited by those who park up, get a view, and then leave. Many people drive past it, without realising they are near some geology.
Looking around there is plenty of geology in the area, most if it appearing to be limestone, though look around and there geology beyond the limestone. Names give hints such as Sandy Hill, as does the landscape. Look to the south, west and north and there are bumps, lots of them. These are evidence of a time when the temperature was much cooler, the ice age, also known as the quaternary age.
If you look to the north you will notice the limestone outcrops of Runscar, Middle Scar and Little Scar, these are amongst a rolling landscape, unlike that of near by Ingleborough. This rolling landscape is what us known as glacial drift, basically clay , sand, rocks and boulders left behind by the glaciers when they dissapeared. You see, glaciers were not pure ice, as they moved along they scoured the land to the sides and base, and picked up debris. Evidence of the clay, can be found in the nearby Ribblehead Viaduct area, as there was a brickworks, bricks are made from clay.
From the EarthCache location, look down Upper Ribblesdale, snd you notice loads of rolling hills, this is the Upper Ribblesdale drumlin field, also known as a swarm.
So, what is a drumlin?
A drumlin is an oval-shaped hill, largely composed of glacial drift, formed beneath a glacier or ice sheet and aligned in the direction of the ice flow. In areas were there have been two glaciers, drumlins may be sligned in different directions. They are widespread in formerly glaciated areas and are especially numerous in Canada, Ireland, Sweden and Finland. A drumlin is a glacial land form.
Whilst there are many variations in shape, the `classic´ drumlin is a smooth, streamlined hill that resembles an egg half buried along its long-axis. They tend to exist as fields or swarms of land forms rather than as isolated individuals, with a typical swarm comprising tens to thousands of drumlins. Viewed en masse, drumlins within a swarm display a similar long-axis orientation and morphology to their neighbors, and are closely packed, usually within two to three times the dimensions of their drumlin length. The majority of drumlins in a swarm have their highest elevation and blunter end pointing in an upstream direction, with the more gently sloping and pointed end, or tail, facing down-ice. The upstream blunt end is called the stoss end and the downstream end called the lee.
Drumlins are not the only landforms that glaciers have left behind. There are also Eskers.
So, what is an Esker?
Glaciers, can have channels formed of water running underneath, and on top of themselves. Over time these channels can get blocked by sediment, and over time the sediment can build up. An Esker is a build up of sediment, but unlike drumlins, which are commonly oval or mound shape , an Esker can be ridge shaped. The ridges may be sinuous, which means having a winding form. Eskers can be singular forms or have many in a locality, their length can vary, from short ridges to long sinuous ridges covering many kilometres.
This being an EarthCache, in order to log it, I ask that you complete the above tasks. Please send the answers to me, and do not include them in your log. You can send them to me by using the message facility or email, both of which can be found by looking at my profile.
1. At the EarthCache location you are on top of Sandy Hill. You will have had to walk up to here, which helps in completing the tasks.
(a) Please describe Sandy Hill in terms of shape, and any specific features.
(b) Can you see any other features nearby which look identical, if so where, and how are they identical?
(c) Would you consider this to be an esker or drumlin, what is the rationale behind your answer?