What you will learn from this earthcache
>Rock layers provide evidence of Earth’s landscapes from the past.
>The oldest rock layers are at the bottom and the youngest layers are at the top.
Recent work on the Ovingham overpass has exposed a series of rock strata. The term rock strata refers to layers of sedimentary rock. These layers form from the processes of weathering, erosion, deposition, compaction, and cementation. The sediment that forms sedimentary rocks is deposited in horizontal layers. Over years, the sediment becomes deeply buried, hardens, and changes into sedimentary rock. These rock layers provide a record of Earth’s geologic history.
The properties of exposed rocks are based on grain size, cementing compounds, hardness, chemical resistance and exposure conditions. Each of these factors will change the visible features of the rocks and rock layers. The size, shape, and composition of the sediments affect the texture and colour of the resulting rock.
• Sandstones are typically made up of sand-sized particles and range in colour from white to red to brown depending on the mineral content.
• Clays such as ochre range in color from yellow to orange, brown, red and purple depending on the type of clay and contamination.
• Shale is composed of fine-grained silt particles, which result in a smooth texture and can be various shades of grey, brown, or black.
Within the earthscience of stratigraphy, geologists and paleontologists study sedimentary rock strata in order to understand where and how sediments were deposited, identify tectonic activity, and determine the relative age of rock layers. According to the geological law of superposition, in horizontal sedimentary rock layers the oldest is at the bottom. Each higher layer is younger than the layer below it.
Visit the listed coordinates and make your observations. You will need to answer the following eathscience questions. Please provide your answers to the cache owner in a timely manner, i.e. less than a fortnight.
-Describe the oldest layer of the strata. Colour and texture? Which layer property is significant?
-Describe the youngest layer of the strata. Colour and texture? Which layer property is significant?
-Which layer has a pink appearance. Which layer property is significant?
