June 1, 2010

International Children's Day – Croatia and many other nations

Although many countries celebrate Universal Children's Day on November 20, and some countries celebrate their own version of Children's Day on other dates, more than 40 countries, many of them former Soviet Union states or communist countries, celebrate children on June 1. The list includes countries in South America (such as Ecuador), Africa (such as Ethiopia), Asia (such as Laos), and Europe (such as Croatia).

Croatia, which is located in south-central Europe, has been an independent kingdom, linked with Hungry and Austria-Hungry, and part of Yugoslavia. It is now an independent nation.







Riddled with Holes

More than half of Croatia is made up of karst landforms, which are created when water drains through rock and dissolves portions of the rock. Karst landforms include sinkholes and caves.

One of the most interesting sinkholes in the entire world is in Croatia. Called Crveno Jezero, or the Red Lake, this lake looks like a deep hole with nearly vertical walls. Some people say that the lake looks like it is at the bottom of a shaft or a pit. The walls feature some small caves, one of which starts above water level and ends below water level, and measuring the bottom of the lake is problematic since it extends down into a cave system of uncertain depth.

The Red Lake is actually deep blue. It is the sheer rocks around the lake that are red.

Visitors to the lake have to park at the top and look (carefully!) hundreds of meters down to the lake. An article I read said that there is no foot access “for tourists,” which hints that locals might have a way to get down there.

There is karst lake nearby called the Blue Lake. It's higher on the hill, and it is both wider and less deep. Tourists can climb down to the water of that lake (it doesn't sound easy, though!).


Some of the caves in Croatia are interesting because they are archaeological sites with ancient remnants of both Neanderthals and modern humans. (I know, ancient modern humans sounds like an oxymoron, a phrase that has opposite words. What I mean is that in these caves there are remnants of ancient homo sapiens sapiens.)

Vindija cave has these sorts of Neanderthal and human bones and artifacts, dating back to around 45,000 years ago, but it also has thousands of cave bear bones dating back more than 150,000 years.

The Caves of Cerovack are called the most beautiful caves of Croatia, but they seem to be more famous for their paleontological and archaeological value than for their geological structures. We have found in this cave the remains of prehistoric humans plus bones of cave bears, cave lions, wild horses, red deer, chomois, and other animals.

I did find a website that has some beautiful photos of rock formations in the Caves of Cerovack. Scroll down and down and down to see all the weird-but-beautiful formations.

Caves on the Web

• Here is a website about caves that's meant for kids!

• And here is a simple experiment that gives some idea of how cave formations form.

• Do you like the idea of a virtual cave tour? This cave is in Wales, faaarr from Croatia, but it's interesting to click-and-seek.

How Do Sinkholes Form?

• That's the question I typed into Google, and I found this short video answer.
  

• Here is a more extensive answer, plus an experiment in which you can make a sinkhole.