The route to the gully and the GZ is a challenging rocky crag that you have to scramble/climb and should not be attempted by geocachers not able to cope with the terrain, by children and in poor weather conditions
Helsby Hill was formed during the last ice age.
Like most Earth materials, rocks are created and destroyed in cycles. The rock cycle is a model that describes the formation, breakdown, and reformation of a rock as a result of sedimentary, igneous, and metamorphic processes.
All rocks are made up of minerals.
A mineral is defined as a naturally occurring, crystalline solid of definite chemical composition and a characteristic crystal structure.
A rock is any naturally formed, nonliving, firm, and coherent aggregate mass of solid matter that constitutes part of a planet.
There are 3 groups of rock:
Igneous rocks- form in two very different environments. All igneous rocks start out as melted rock, (magma) and then crystallize, or freeze. Volcanic processes form extrusive igneous rocks. Extrusive rocks cool quickly on or very near the surface of the earth. Fast cooling makes crystals too small to see without some kind of magnifier. Basalt is dark rock, gray or black on a freshly broken surface, and weathers brown or red, because it contains lots of dark-colored minerals.
Some basalt contains light-colored crystals. Dacite and andesite are medium in color, and contains medium amounts of dark minerals. Rhyolite is the lightest colored volcanic rock. Rhyolite contains very few dark minerals, but sometimes, rhyolite cools so fast that it quenches and forms volcanic glass instead of crystallizing. Volcanic glass looks dark because of the way light passes through it. Obsidian is volcanic glass.
Intrusive igneous rocks cool in plutons (Pluto was the Roman god of the Underworld.) deep below the surface of the Earth. Slow cooling allows the growth of large crystals. Crystals in intrusive rocks are visible without magnification. Granite has the same minerals as rhyolite, but in much larger crystals. Diorite is the intrusive version of andesite, granodiorite is the intrusive version of dacite, and gabbro is the intrusive version of basalt.
Metamorphic Rock- Metamorphic rocks form when sedimentary, igneous, or other metamorphic rocks are subjected to heat and pressure from burial or contact with intrusive or extrusive igneous rocks. ("Meta" means change, and "morph" means form.) Heat and pressure from burial cause molecules of flat minerals like mica to line up perpendicular to the direction of greatest compression. Deep burial means higher pressure and hotter temperatures, and very high temperature and pressures cause the formation of new minerals, and mineral grains.
Low-grade metamorphic rocks like slate and phyllite break in flat pieces, and have a sheen on the surface. Schist is shiny, and many schists contain garnets, staurolites or other mineral crystals that have grown within the rock. Gneiss is a foliated metamorphic rock. Layers of dark and light minerals stripe the rock, and sometimes it is possible to see how the direction of pressure deep in the Earth changed as the minerals formed. The change in direction forms eye-shaped pods of minerals, called augens ("augen" is German for "eye.") Quartzite is another metamorphic rock. Quartzite is metamorphosed sandstone. Another common contact metamorphic rock is marble. Marble forms when limestone is intruded by a pluton which heats the limestone.
Sedimentary Rock- Sedimentary rocks are those rocks made up of pieces of other rocks. We call the pieces of rock "clasts" (Clast means "broken piece"). A clast is a piece of rock broken off of another rock. Clasts of rock are eroded from larger rocks, transported (moved) by wind or water and deposited in a basin.After some period of time, the clasts are lithified (lithos is the Greek word for stone). The sedimentary rocks we see today were once gravel, sand, silt, mud, or living things. We decide what to name sedimentary rocks based on the size of the clasts that make up the rock. For most sedimentary rocks, this is easy.
Sandstone is made of sand, siltstone is made of silt, mudstone is made of mud and so on. Even volcanic ash can become sedimentary rock! The only hard ones to remember are conglomerate and breccia. Conglomerates are made up of rounded, gravel-size particles (To a geologist, gravel is anything from 2mm to 4 meters in diameter), and breccia is made up of angular, sharp-edged, gravel-sized clasts. Limestone and chert are classified as sedimentary rocks, but most limestone and chert are grown by living organisms rather than broken from other rocks. Some limestones have fossils, but most limestones and cherts have recrystallized, and the remains of the creatures that made them are no longer visible.
Did you know that the sand grains in sandstone can give you information about the past?
The presence of feldspar and lithic grains means that the sediment is generally close to the hill or mountains where it arose.
Detailed studies of sandstone give insight into its provenance, which is the kind of countryside that produced the sand.
The degree to which the grains are rounded is a sign of how far they were transported.
A frosted surface is generally a sign that sand was transported by wind—that, in turn, means a sandy desert setting.
Various features in sandstone are signs of the past environment:
Crossbedding (truncated, tilted sandstone layering), you can see this at the top of the gully, this forms during deposition on the inclined surfaces of bedforms such as ripples and dunes, and indicates that the depositional environment contained a flowing medium, such as rivers, tide-dominated coastal and marine settings.
Interbeds of shale or conglomerate may indicate episodes of different climate.
After the sandstone was formed the Earth's crust was deformed and then fractured the horizontal sedimentary sandstones. As the Earth's crust continued to deform upwards the sandstone was pushed out and tilted at distinguishing angles. This movement took millions of years and during the last Ice Age these protruding rocks formed and resulted in distinct features such as this Hill being visible.
The Last Ice Age is the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. What occurred then, was glaciers covered huge parts of the planet Earth.
At one point during the Ice Age, sheets of ice covered all of Antarctica, large parts of Europe, North America, and South America, and small areas in Asia. In North America they stretched over Greenland and Canada and parts of the northern United States. The remains of glaciers of the Ice Age can still be seen in parts of the world, including Greenland and Antarctica.
But the glaciers did not just sit there. There was a lot of movement over time, and there were about 20 cycles when the glaciers would advance and retreat as they thawed and refroze. These glaciers moved and carved out the landscape that we have today, just like Helsby Hill.
During your visit to the Clashooks Gully you will see clear evidence of erosion at the GZ due to the large boulder being in place.
Rocks are made up of minerals which are naturally occurring substances like quartz, feldspar and a host of others, these two are the most common.
The grains of the rock in a sandstone for instance are held together by cement. This cement can be iron, calcium carbonate, or silica all of which were deposited after the sand grains were deposited on a beach or in a sand dune and these forms were buried deep in the earth.
So water hitting the rock acts as kind of an acid agent.
It attacks the rock by weakening the bonds that hold the various crystals together, or dissolves the fine grained rocks such as limestone, using the same method.
These weakened crystal boundaries are then more susceptible to the impact of other grains being carried along by the water. The mineral attack then small depressions that become deeper and deeper ultimately weakening the surrounding stone, which will break away in larger pieces and then create divides in the rock or a gully.
At the GZ you will observe lots of weathering to the rock and the hill, you will be able to see the effect that this is having on the locations appearance.
Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material.
There are 3 types of weathering, physical, chemical and biological.
Carry out some research and understand how the 3 types differ and the effect that they have on the rock.
Now for the fun part, In order to log this EarthCache you will be required to email us through our profile page or use the message centre to send us the answers to the following questions after your visit to the location
A photo on your found log is now a logging requirement (EarthCache guidelines) anyone logging a find without a photo will have the log deleted.
1. Feel the rock around you that the hill is formed off, explain how it feels and what it looks like.
2. Having observed the location what rock is Helsby Hill formed from?
3. If you had feldspar and lithic grains in the sediment, what would this indicate?
4. Can you now explain is this rock igneous, sedimentary or metamorphic?
5. Please explain how the rock gets its colour.
6. Having observed the location please explain the types of weathering present and what did you see at the location to indicate this to you?
7. At the GZ you will find a large boulder that has fallen down the gully due to erosion and landed near by, please assess it and send me the measurements of its width, height and length.
8. Using what you have learnt please explain how you believe the gully was formed?
9. Please explain how Helsby Hill was formed.
10. In order to evidence that you have visited the location a photo of you/GPS at the GZ next to the boulder in the gully must be posted on the find log, if this is not done your log will be deleted.
Please do not put any of the answers to the questions on your cache log as I will have to delete it
Please enjoy the EarthCache experience and you don't have to wait for a reply from us before logging, although anybody logging without emailing the answers and completing all of the tasks will have their log deleted.
Happy EarthCaching.
Congratulations to Sir PPR on being FTF on 10/04/17.