What Does The Freshwater Sunfish Eat

What in the world .... a Blue Hole?

Better late than never. Actually, I do not have time to write long blog posts, and I announced some time ago to try to keep it shorter. We'll see if I succeed this time.

In my last entry, there was the misconception that this is the first article in the What in the world ... Series would be. In fact, there are the five. You can find them if her right in the categories of "What in the world ..." clicked. =====>

I still have problems with the line spacing, the blog software seems to randomly pick out one line or 1.5 lines. If anyone has a solution for it, I am pleased with a comment.

Blue Holes

space: [up to many tens km long cave system]
Occurrence: In regions with coastal carbonate
potential danger: [less dangerous]
time scale: [Recent]

What is a Blue Hole?

Today it is blue. Very blue. I translated the term do not realize, because it is a kind of technical term. A Blue Hole is one of those phenomena that can be endlessly fascinated stare long enough to ask, how does something like that, and forgetting the time. The solution is relatively simple if one thinks in long periods of time.

(aerial view of the Great Blue Hole in Belize)

The Blue Hole is a special case of a depression in the limestone, known as a sinkhole, and that it is a surface water or groundwater flooded cave system . The circular entrance belies the fact that such a branched, may be located several miles long cave system. A blue hole may extend over 100 feet straight down, so that the dark blue color of the water next to the flat archipelagos particularly stand out.

The term Blue Hole is not used consistently. One can be divided roughly into the category of Ocean Blue Hole and Inland Blue Hole, while, as the name suggests, an Ocean Blue Hole is primarily with sea water at the coast and a national Blue with fresh water (surface water or ground water) filled. Inland Blue Holes are also known as cenotes. There are many other classifications that we can not but have to go through. There are no unique symptoms and there are thousands of cenotes and blue holes in the world known to be connected with the highest in the Caribbean and Central America.

http://www.laputanlogic.com/images/2004/02/17-YAYD0T2N00.jpg
(Zacaton Cenote, Mexico, Source: Ann Kristovich)

The largest and most blue holes are found in the Bahamas and Belize. The deepest blue hole in the world with over 300m depth is the Zacaton in Mexico.

http://www.stoneaerospace.com/news-/pictures/ZacatonMission05152007-001.jpg
(scan of Zacaton, NASA mission DEPTHX, Source: Stone Aerospace / Team DEPTHX)

http://www.stoneaerospace.com/news-/news-zacaton-mission3-01.php
(NASA Mission Report DEPTHX, Source: Stone Aerospace)

ensteht Like a Blue Hole?

(not Simulationisten can also skip)

The process of creation of Blue Holes is where tens of thousands of years in the past, the foundation years, however, up to several hundred million. Favorable conditions for the formation can be found on carbonate platforms. This is a sedimentary body deposited in shallow water limestone in thin layers. The limestone is formed by the Metaboslismus from microbes or from the skeletons of sessile (fixed) organisms such as corals. While you can find the Blue Hole in every climate zone in theory, the only form in warm waters Riffplattformen (Which limits the occurrence of the Blue Holes by movement of the tectonic plates of course). The platform is qausi a solid, solid plate.

Over the last ice ages, the last Eismaximum was 20,000 years ago, the sea level dropped by up to 130 meters. This means that some of the old Riffplattformen were dry. Particularly old structures are due to stresses crossed by cracks in the surface water can penetrate and dissolve the limestone, causing formation of karst caves. The actual, prominent hole that one finds today, may arise if such a cave roof collapsed.

http://farm2.static.flickr.com/1220/713701474_cabe787b55.jpg

(a "dry start" in a cenote, after the collapse of a cave ceiling, Source: Cesar Ramos)

During the late glacial period the sea level rose again and filled the cave systems. Equivalent of this happened with groundwater fluctuations on the mainland.

properties (and dangers) of the Blue Holes

blue holes and cenotes are a paradise for divers. The cave structure ranges from simple systems, such as the Guardian of the Blue Holes on Andros in the Bahamas, Iceland to highly complex branched systems.

http://www.tamug.edu/cavebiology/Bahamas/caves/images/GuardianMap.jpg
(map of the Guardian Blue Hole, Source: Brian Kakuk)

dive
(dive in a cenote near Playa del Carmen, Mexico, source: Rob laddish)

are the famous cenotes of Mexico state of Quintana Roo and Yucatan. There are found in the 1000 cenotes of a few tens of meters to a few hundred meters depth, and probably the largest underwater cave systems in the world, the Ox Bel Ha and the Sac Actun with about 180km in length.

http://www.caves.org/project/qrss/sacactun2004.jpg

(cave system of the Sac Actun, source: QRSS, 2004)

20total.gif http://wetworx.nl/Cavemaps/Ox 20Bel%% 20ha%

(Ox Bel Ha cave system, Source: GEO)

flow These underground river systems such as all the rivers toward the ocean surface with numerous entrances and are connected, which not all are explored, as they are in the jungles of Central America is difficult to locate and only a few meters can be great.

http://www.elrivalinterior.com/actitud/Nutricion/cenotes-tulapina.jpg

(one in the jungle hidden entrance to the cave system of Ox Bel Ha, Tulapina cenote, Source: podwodne groty Blog)

Since the conditions usually anoxic, thus in oxygen, are and can penetrate also little light in the caves, there are less ways of life, as in the light flooded shallow water. They work but only at first glance dead Besides micro-organisms or cancers can be found in fact even large creatures such as manatees, sea cows, in the Mexican cave systems that live in shallow water and the rivers of Central America and by previously unknown access from the coast into the underwater caves penetrate.

http://photo.starnet.ru/Thematic_Wallpapers/Zhizn/Vodnyj_mir/Lastonogie/images/MANATEE.jp g

(a Manatee, here on the coast. Through underwater entrances they can penetrate into the cave systems)

In Blue Holes can land fossils from the era can be found before the flooding, most recently in 2007 a 1000-4000 year old country crocodile Iceland on Abaco in the Bahamas.

http://i.livescience.com/images/071207-croc-skull-02.jpg

(~ 2500 year old skull of the crocodile country of Abaco Iceland, source: Nancy Albury, The Antiquities , Monuments and Museums Corporation)

Blue Holes are safe as long as one goes into it not in it. The easiest way to get in the cave system of a Blue Holes in difficulty, to get lost easily. You have to remember is that the cave network extending in all directions and the water offers the possibility to move freely up and down. For this reason, divers carry a lead rope with you. Not infrequently there is a separation layer between sweet and salty sea water including ground water, which acts as a second water surface at the light breaks, so that divers can easily lose sight of.

http://www.gue.com/files/page_images/expeditions/Exploration/Cave/mexico/030_DSCF0033.jpg

(unreal dive in the caves of Ox Bel Ha, source: D. Riordan)

Another danger are strong currents, especially in the küstennahnen Blue Holes, which are exposed to the tides. Through the turmoil, even small boats can be pulled down. Due to the very different length of the cave passages can also achieve even weak currents in narrow passages of a high pressure so that it can happen that one in. Although in an opening, but not to swim back.

use role-play

I have to role players who require no Explain how to use caves, so only a few and suggestions.

were in the absence of natural explanations for the cenotes of the Maya in Yucatan the entrance to the underworld. Who sacrificed the circular abyss treasures including gold objects, and others. Human sacrifices are also shown. Last but not least, the Maya settled in the vicinity of the cenotes, as they were in the dry season the only water supply.

indicated the Bahamian natives (and apparently still do) the Blue Hole as a "blow holes" caused by the monster Lusca, a mythical creature half octopus, half shark, which is probably due to the giant squid finds stranded declining. The "breathing" of the monster, which is perceived in the Blue Hole can be explained by tides, currents and water level fluctuations, as well as a whirlpool-like bubbles in these cave entrances. However, there is a through ball for a cthulhoiden myth.

last noted was a very useful playing aid, a collection recorded under water river systems, which was partly linked above already.

http://wetworx.nl/Cavemaps/cavemaps.html

(Source: www.wetworx.nl )

The accuracy of the maps varies widely, but there are wonderful specimens, which can be used as a 1:1 Dungeon cards.

http://wetworx.nl/Cavemaps/Sac 20Actun%% 201.jpg
(part of the Sac Actun cave system, Source: www.wetworx.nl )

Conclusion:

Well, it looks like I have saved at most a quarter of the text. I do not do things by halves, and would probably also handle the next topic again thoroughly. Accordingly, please be patient, because I can not afford weekly frequency.

Thanks for reading and dived ...