The Marsden War Memorial is situated in Marsden Park off Manchester Road. It commemorates Marsden men who fell in World War 1 and World War 2. The memorial includes two very different types of stone, Limestone and Granite. Neither are local - Marsden could be described as a one-stone town with the local gritstone being predominantly used for most structures. There has been some great use of the chosen stone in this attractive memorial and this EarthCache allows you to take a closer look before answering some very simple questions. You are not expected to have any former knowledge of geology, reading the information here is all you need to do in order to answer the questions.
Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO₃) in the form of the mineral calcite. It most commonly forms in clear, calm, warm, shallow marine waters. That type of environment is where organisms capable of forming calcium carbonate shells and skeletons can easily extract the needed ingredients from ocean water. When these animals die, their shell and skeletal debris accumulate as a sediment that might be lithified into limestone. Their waste products can also contribute to the sediment mass. Limestones formed from this type of sediment are biological sedimentary rocks. Their biological origin is often revealed in the rock by the presence of fossils.
Limestone can be clastic or non-clastic. If it is clastic or bioclastic then grains and/or broken or whole shell fragments will be visible; if non-clastic or chemical then it will appear crystalline and no clasts (fragments/grains) will be visible visible. Impurities (such as clay, sand, organic remains, iron oxide, and other materials) will cause limestones to exhibit different colours, especially with weathered surfaces. Another colour you may see are areas of black on the limestone. In a town such as this, this staining of the rock is caused by pollution from the industrial times when smoke from coal fires left a black crust on many rock surfaces. Limestone is generally a softer rock due to the sedimentary make up, so it may be used for memorials because it is easy to carve, the texture or the colour.
Granite is a light-colored igneous rock with grains large enough to be visible with the unaided eye. It forms from the slow crystallization of magma below Earth's surface. Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals. This mineral composition usually gives granite a red, pink, gray, or white color with dark mineral grains visible throughout the rock.
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 three types of weathering, physical, chemical and biological.
Physical weathering is caused by the effects of changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water. There are two main types of physical weathering:
Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.
Exfoliation occurs as cracks develop parallel to the land surface a consequence of the reduction in pressure during uplift and erosion.
Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic. These chemical processes need water, and occur more rapidly at higher temperature, so warm, damp climates are best. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils. There are different types of chemical weathering, the most important are:
Solution - removal of rock in solution by acidic rainwater. In particular, limestone is weathered by rainwater containing dissolved CO2, (this process is sometimes called carbonation).
Hydrolysis - the breakdown of rock by acidic water to produce clay and soluble salts.
Oxidation - the breakdown of rock by oxygen and water, often giving iron-rich rocks a rusty-coloured weathered surface.
Biological weathering is the impact of living organisms on the stone. Trees put down roots through joints or cracks in the rock in order to find moisture. As the tree grows, the roots gradually prize the rock apart. Many animals, such as these Piddock shells, bore into rocks for protection either by scraping away the grains or secreting acid to dissolve the rock. Even the tiniest bacteria, algae and lichens produce chemicals that help break down the rock on which they live, so they can get the nutrients they need.
Questions to Answer (Logging Requirements)
Please visit the listed coordinates at the war memorial. The questions all relate directly to the information provided in the listing so you should be able to answer everything from GZ with no extra reading required - anything mentioned in the questions is explained in the listing. Please ensure you send in the answers at the time or soon after you log your find, as logs may be deleted if no attempt at the answers are made.
Question 1 - The main memorial and carved lions are limestone. Explain why limestone might have been chosen, bearing in mind gritstone and sandstone would be available locally?
Question 2 - The plaques containing the rolls of honour are made of granite, which is a harder stone to carve than limestone. Explain why this alternative stone might have been chosen, given words have been carved into the limestone elsewhere?
Question 3 - Examine the texture of the limestone. The right hand side (west) is particularly interesting. Describe the texture and whether you can find any evidence of shell fragments or fossils in the stone. Is the limestone used for the carvings the same? Tell me, is this limestone clastic or non-clastic?
Question 4 - Focusing on colour, can you spot any obvious impurities in the limestone or would you describe it as a pure limestone?
Question 5 - Where is there evidence of industrial pollution? Why is it only in some areas?
Question 6 - Finally how well do you think the memorial is weathering - please rate the general condition of the below areas, between 1 and 10 - 1 being very poor and 10 being very good
- the condition of the flat cut limestone monument
- the condition of the carved limestone such as the lions
- the condition of the granite plaques
Finally - Please include a photo or yourself, GPSr or personal item with the memorial in the background taken from the steps near the rockery. Under revised guidelines, this is now a requirement, as it proves you visited the site. Please do not include photographs close to the memorial that would give away the answers.
Thank you for visiting the Marsden War Memorial EarthCache
The series is dedicated to those who fought for their country. "We will remember them!”
If anyone would like to place a War Memorial Cache of your own then please do so. We would ask if you do so please contact Just-us-Two through their profile page or firstname.lastname@example.org
so they can keep track of the numbers
Please note, physical caches are not allowed to be placed on the actual memorial or within the boundary of such memorials. Please treat war memorials with the appropriate respect when finding or hiding geocaches.