Fossils in Malta
Maltese rocks are rich in fossils, and scientific papers from the mid 19th centry describe some of the early palaeontology. For the modern day fossil hunter, getting up close to fossils in Malta can be difficult. Either the cliffs are sheer and inaccessible, or else exposed fossils are found on private property. The rugged cliffs of Malta's grand harbour are one of the few places in Malta to see fossils safely.
This Earthcache takes you along the rugged coast below the imposing 16th century ramparts of Fort Saint Elmo. Walk anywhere in Valletta, and you will never be far from gorgeous honey coloured stone - either as vertical cliffs of natural rock, or else as the structural basis of so many of the historic buildings. But what is this stone?
Suggested route
From the trailhead waypoints a rough track with sections of steps leads around the headland to the posted coordinates. There is no particular virtue in going one way or the other. Better, use one route in and the other one out.
Your tasks
This EarthCache asks you to look at the rocks you are walking on and beside, and make some simple deductions about the nature of the rock you see.
Wear sturdy footwear and make sure you don't slip anywhere. At places a steep drop to the sea isn't far away from the rugged path.
To log this EarthCache go to the posted coordinates (a flight of stone steps cut into the rock) and answer the following questions.
1. Look at the stone steps under your feet and see if you can find some fossils. Describe the appearance of what you see.
Now walk the short distance to WP 2, a deep cutting through the limestone.
2. Look at the near vertical rock wall below the ramparts which has a right-angled corner at the left end. Describe the prominent fossil seen at about eye level here.
3. What marine creature alive today most resembles the fossils found at the posted coordinates and WP2?
4. Based on these observations, what is the most likely type of rock exposed here? (You will need to refer to the text below.)
5. Please add a photo of you and/or your group here, or simply a photo of the general area you don’t wish to appear in your log.
Send me your answers either via my profile or via the messaging geocaching.com (Message Center), but please log this cache "Found it" before hearing back from me. I will contact you if there is a problem.
Malta's geology
The Maltese Islands are made up of horizontally layered marine sedimentary rocks. These rocks are lime-rich and many skeletal remains such as shell fragments are found. There are five major rock strata (rock layers) found in Malta.
The five major geological strata are:
Lower Coralline Limestone. This is the oldest exposed rock at the Maltese Islands (30-25 million years) and is the lowest stratum. It is a highly crystalline rock, very resistant to erosion. The large number of fossils, including snail casts and coral indicate that this layer was formed in shallow marine settings.
Globigerina Limestone. This limestone overlies the Lower Coralline Limestone. Two typical fossils from 30-25 million years ago that can be found within this rock are the Sea Urchin (Echinolampas lucae) and the Sand Urchin (Schizaster parkinsoni).
Blue Clay. Soft blue clay lies above these limestone layers, and consists of fine lime grains and kaolinite, a clay mineral, which makes the layer compact when dry.
Greensand. This is a thin layer (less than 1m) which attains its orange colour from oxidisation and exposure to air. Fossils of the Domed Sand-Dollar (Clypeaster altus) from 15 million years ago are found in the greensand strata.
Upper Coralline Limestone. This is the youngest and topmost layer of rock found in Malta and forms plateau on the highest ridges of the Maltese islands. This rock is similar to Lower Coralline Limestone in composition, having numerous fossil algae species. Coral fossils found in these rocks are 15-10 million years old and their globular shape is distinct from other species.