This writing prompt brings out the scientist in me. I can't look at "how did it get there" without thinking about the volcano itself. Volcanic islands occur because of a weak area in the crust on the ocean floor. Maybe there is a channel deep in the crust or maybe pressure from the mantle builds, but magma from the mantle escapes up through the crust and erupts into the bottom of the ocean. The magma touches the frigid ocean water at the ocean depths, cools, and solidifies. Over millions of years the liquid magma bubbles up over the gradually rising hill, cools, and adds another layer of crust. If this volcano stays active, eventually it rises above the water, forming a volcanic island.
Now, the ocean floor is constantly moving due to plate tectonics. Over geologic time spans, the volcano is slowly moved away from the weak area where magma can escape the crust. At this point, the volcano becomes extinct. The weak spot in the ocean floor is now under a new piece of ocean crust, and so a new volcano starts forming. This process forms chains of volcanoes called archipelagos. Examples of these island chains include Hawaii and the Galapagos islands.
After even more time has passed, erosion from wind and water slowly wears away at the volcano. The volcano gets smaller, and the island disappears as all the above-water land is eroded away. If you look at an archipelago chain, you will find the younger, shorter volcanoes close to the weak area of the mantle. That is where the active vulcanism is occurring. As you move down the archipelago, you will find taller extinct volcanoes. Even further down the archipelago, if you look underwater, you will find even older volcanoes that have eroded so far that they have lost their island (these are sea mounts), and are basically underwater mountains.
Looking back Ball's Pyramid, the volcano pictured above, I just see one volcanic island. The picture is close-cropped, so there may be other volcanic islands out of view. It may be that that this is the first volcano from this new weak spot over the crust, and that a new volcanic island is slowly being built under the water. Or it may be that this island is further down an archipelago and that there are younger islands that we cannot see. The caption relates that this island is 7 million years old, and it does not appear to be currently active, as evidenced by the tall, sharp peak. (Volcanoes that have recently erupted tend to have a sunken caldera bowl at the top of the mountain, not a tall thin spear).
Now, on to the mystery. In general, volcanic islands are fairly desolate places. They do not even have soil for plants to grow. It is only after erosion starts to wear out the rock, and small algae & lichens start to grow then decompose, does soil start to appear. Since the island is surrounded by salt water, most of the plants and animal life do not have a way to get to the island. Birds can fly to the island. Animals strong enough to swim long distances through the ocean, perhaps like a crocodile, could make it to the island. Sometimes insects can fly or be carried through the wind long distances. Other small animals might be able to be adrift on vegetation and get washed on to the island. But, overall, it takes a very long time to life to get started on a volcanic island.
Places like Hawaii that are a lush tropical paradise have two things going for them: they have been around for a long time, so this succession process has occurred and the original islands were much closer to the continent which allowed for animal migration. The early Hawaiian islands were closer to the southern coast of Asia, so some reptiles, small mammals, and birds were able to migrate over to the new islands. Then, as newer islands formed further out to sea, the animals only had to migrate a short distance to the new island. Over time, the original islands close to the continent eroded away, and the animals became trapped on the Hawaiian islands that are now too far out to sea to allow the land-bound animals to leave.
Ball Pyramid does not appear to be a lush tropical paradise. I see bare rocks, without evidence of many plants or animals. This volcanic island is either too young to have developed much of an ecosystem or formed too far away from other islands or a continent to allow plants and animals to easily colonize the island. The caption claims that the island is about 7 million years old. That sounds pretty old for us, but on a geological timescale that is a young island.
The mystery clue states that 2 climbers found something in the soil, hidden by a bush. Something that was totally surprising and did not fit in with the expectations of this volcanic island. Looking at such a young island that has not been well colonized, I would not imagine there is a very deep layer of soil. Something that surprising that you might find in volcanoes, if you didn't know about geology, are diamonds! Diamonds are formed from the heat of a volcanic eruption. Some of the most well-known diamonds in the world are found in Africa, and are the site of ancient volcanic eruptions!
What else would be surprising? Well, obviously there could be any number of things that were found on the island that wouldn't be expected to be there. For example - I wouldn't expect to find dinosaur fossils on this islands for a couple of reasons. First of all, if the island really is 7 million years old, it is too young. Most dinosaurs were at least 65 million years ago (if not hundreds of millions of years before that), and this island wouldn't have been around long enough to have dinosaurs live, die, and become fossilized on it. In general, you wouldn't expect to find any kind of fossil on this island. Without considering the timing factors, this is a volcanic island. As it was formed, molten lava was pouring over it's surface. Bones would be burned up. And again, since it is so young, it's likely there is not a very deep sedimentary soil layer on this island (most fossils are found in sedimentary rocks).
What else would be a surprise? A deep cave that lead to a freshwater lagoon? Caves are probably not too hard to imagine on a volcanic island. As magma bubbles and lava pours, it does not pour evenly. Add in plate tectonics, and cracks can occur. Rainwater running down from the mountains could also help carve out caves. It is possible that over the 7 million years (or whatever portion of that time it was an island above the water) that caves were carved out of the solidified lava. And it is conceivable that the freshwater from rain could run down into these caves and collect into some sort of underground lake. I wouldn't expect it to have a fresh source from groundwater, since it is out in the ocean and groundwater is usually found in aquifers on continents. But, over such a long period of time, the fresh rain water could have collected into quite a big lake at the bottom of a cave.
And we can go on and on. So - what do you think the answer to the mystery could be? Write your thoughts in the comments. No cheating and looking it up! I'll check back in with you in a couple of days and tell you the answer!
Missy Bree
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What a colossal waste of my time reading this.
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