This EarthCache is part of my new series, Earth Around The Earth. A new EarthCache will be placed in every foreign country that I go to. This is the first one in the series.
This geocache is at the lovely Ramore Head.
Ramore Head is located in the busy seaside town of Portrush, Co. Antrim. Now famous for its amusement arcades, ice creams and other seaside treats, in the 18th and 19th centuries it was famous for an altogether different type of ‘Portrush Rock’.
The ‘Portrush Rock’ was first discovered by Reverend William Richardson, and described in 1799. It was announced as a ‘fossiliferous’ basalt and thus sparked a serious scientific debate that lasted for a number of decades.
The site is designated as both an Area of Special Scientific Interest and as a National Nature Reserve.
Ramore Head is a rocky headland in Portrush, County Antrim
Ramore Head and The Skerries ASSI is located at the north of Portrush.
An intrusion of Tertiary dolerite has pushed into shales of Jurassic (Lower Lias) age, producing a fine grained, dark rock known as hornfels, which contains abundant fossils, particularly ammonities. This is the site of an historic geological argument about the origin of basaltic rocks. Evidence from this site supported the theory that basalt is formed from cooled volcanic lava.
In addition, Portrush sill is an unusually complex layered intrusion. Locally important breeding populations of kittiwake, black guillemot and eider
Hornfels :
Hornfels is a metamorphic rock formed by the contact between mudstone / shale, or other clay-rich rock, and a hot igneous body, and represents a heat-altered equivalent of the original rock. This process is termed contact metamorphism. Because pressure is not a factor in the formation of hornfels, it lacks the foliation seen in many metamorphic rocks formed under high pressure and temperature regimes. Pre-existing bedding and structure of the parent rock is generally destroyed during the formation of hornfels. It is often difficult to identify hornfels without microscopic observation, or knowledge of its association with a magma body, as it is typically non-descript inhand specimen. Under a microscope the structure of hornfels is very distinctive, with small, generally equigranular, mineral grains fitting closely together like the fragments of a mosaic or a rough pavement.
Basalt :
Basalt is a mafic extrusive rock, is the most widespread of all igneous rocks, and comprises more than 90% of all volcanic rocks. Because of its relatively low silica content, basalt lava has a comparatively low viscosity, and forms thin flows that can travel long distances. It is also found as intrusive dikes and sills. Many moon rocks brought back by Apollo astronauts are of basaltic composition. Basalt is the volcanic equivalent of gabbro.
Here are the different stages that you will have to complete
Stage One
1. In the description, a serious debate was mentioned, and it was between 2 different geological schools. What were their names?
2. What did these 2 schools believe
Stage Two
3. Describe the rocks. Focus on their colour and texture
4. Are the rocks sedimentary, igneous or metamorphic
5. Focus on the biggest rock. What is the predominant colour of the lichen.
Stage Three (Optional)
6. Include a photo of yourself or a personal item at Ramore Head
This cache was placed with the kind permission of Causeway Coast & Glens Borough Council