Different forms of Tufa at the Goat's Twin Hair Cave
This EarthCache is about different forms of Tufa which can be found after a hike to the Goat's Twin Hair Cove. I highly recommend you to head for this EarthCache from the south, the views are spectacular and the fauna is just amazing. But you're advised to take enough water with you since the hike can be quite strenuous. You may also take a torch along with you as you are going to enter a cave.
In order to find this EarthCache it is necessary to enter the Gibraltar Nature Reserve. The Opening Hours are Mon-Sun 09:30 - 18:15 and the Last entry at 17.45 Please note that you must stay on the trail at all times. You can enter the cave itself tho.
As you walk you may see the bright limestone. The Gibraltar Limestone consists of greyish-white or pale-gray compact, and sometime finely crystalline, medium to thick bedded limestones and dolomites that locally contain chert seams. This formation comprises about three quarters of the Rock of Gibraltar. Calcite, the mineral that makes up limestone, dissolves slowly in rainwater. Over time, this process can form caves. For this reason the Rock of Gibraltar contains over 100 caves. You are going to visit one of them and find a few different forms of that tufaceous limestone.
Tufa is a variety of limestone formed when carbonate minerals precipitate out of ambient temperature water. So when slightly acid water slowly finds its way through the limestone it dissolves Calcite. As it reaches the surface the water will evaporate and percipitate the dissolved calcite behind. Tufa will form.
If the water surfaces on an even surface e.g. the ceiling of a cave, stalactites will form. But what will happen if this happens on a more vertical surface? Here are your tasks to solve in order to log this EarthCache:
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Go to the listed coordinates - you will find the entrance to the Goat's Twin Hair Cave. Now enter it. Look above yourself - what do you see? Describe the structure and texture.
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Go to Stage 2: You are going to find two different forms of sintered Calcite - one has a horizontal structure and the other one is chaotic - with a structre often discribed as a "Cauliflower" Please measure these two Forms and tell me the Size.
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Make a guess how the horizontal structures have developed? Think about the way the Stalactites form...
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I'd love to see some Pictures of you, your GPSr or your mascot infront of the Cave. Attach at least one Picture to your log which shows that you had been to the cache's site! 
You can write me those Answers via my E-Mail or the Message-Center. You can log the Cache right away, if there's something wrong with your answers I'll let you know. I hope you are going to enjoy this Cache!