There's a thread by Redrobes in the Tutorial section. I went ahead and stickied it because of it's usefulness. It is here.
There's a thread by Redrobes in the Tutorial section. I went ahead and stickied it because of it's usefulness. It is here.
If the radiance of a thousand suns was to burst at once into the sky, that would be like the splendor of the Mighty One...I am become Death, the Shatterer of worlds.
-J. Robert Oppenheimer (father of the atom bomb) alluding to The Bhagavad Gita (Chapter 11, Verse 32)
My Maps ~ My Brushes ~ My Tutorials ~ My Challenge Maps
I'm sure the other post is comprehensive, I haven't read it for its physics/hydrology/chemistry content.
**Puts on his Chemistry/Physics Hat**
All liquids move towards a point of "lowest energy" (i.e. closest to the centre of the relevant planet) by the path with the "least resistance".
Least resistance has two parts: descent rate and the ability for the water to alter its surrounds. Given the options of trying to make a gully in granite or in nice loose black soil... the river will move to the soil and then take the path which maximises the descent and takes the path through the most "movable" material.
Take an example with a big mountain range. The river will move fairly straight through natural cracks in the rocks (opening them up further... see The Grand Canyon) and take very few sharp turns, rarely double up on itself or anything similar without a VERY VERY good reason.
Once it leaves the mountains it entirely depends on the slope to the ocean. If the land is basically flat (barely ANY slope at all) the river will wander all over the place until it finds the path with the most easily moved material.
My advice: Use Google Maps to look at China. Plenty of rivers. They all start in mountainous areas, flow straight for a long-ish period of time and then start straying when they hit the wide flat lands across most of central and coastal China.
Deltas = wierd places where rivers get confused and hedge their bets by splitting and taking as many paths as they can push water through. Nile River Delta, end of the Mississippi river...
Australian Rivers = we have a near monopoly on the concept of a "sand river". There is a river flowing, but it's underneath/through 5m depth of sand and only really flows above-land when you've REALLY got water flowing.
As an explorer, if you ever got lost, the solution to getting to somewhere nice and hospitable was find a river and follow it. Eventually you will hit the coast. Don't try this trick in Australia... it doesn't work quite right and we have the dead 1800s-era explorers to prove it.
Explain the Yucatan...
OK, Juggernaut, have some REP for that bit science on rivers!
My curious question now regards the Yucatan Peninsula, and the Island of Cozomel. I've been to Cancun, Mexico, on vacation a few years ago, having recently (at the time) learning about the propensity of underwater rivers in southern Mexico. The island of Cozomel (largest island off Mexican coast, very near Cancun.
Most of the Yucatan is extremely flat, but there are almost no surface rivers there. Sinkholes everywhere. Underground rivers everywhere.
I visited a "park" that contained a sinkhole right near the coast, about a half mile away from the sea. Fresh water rose from the sinkhole and formed a short surface river called a "Ria" that reached the sea.
Cozomel is really not that big, yet underground rivers course meandering around the reaching the sea.about 5 meters under the surface.
I've always wondered about the science regarding that... Can anyone answer, Juggie or Waldronate?? It seems almost bizzare.
GP
Gamer Printshop Publishing, Starfinder RPG modules and supplements, Map Products, Map Symbol Sets and Map Making Tutorial Guide
DrivethruRPG store
Artstation Gallery - Maps and 3D illustrations
Could be the Yucatan Peninsula is the remnants of that GINORMOUS Meteor Impact that spelled the end for our favorite dinosaurian friendsOriginally Posted by Gamerprinter
Daniel the Neon Knight: Campaign Cartographer User
Never use a big word when a diminutive one will suffice!
Any questions on CC3? Post them with CC3 in the Subject Line!
MY 'FAMOUS' CC3 MAPS: Thunderspire; Pyramid of Shadows; King of the Trollhaunt Warrens; Demon Queen's Enclave
The Yucatan is limestone
The Yucatan is mostly liimestone. Tropical rainforest or at least jungle at the surface, thus rainfall becomes acidic and "melts" holes into the surface and carves channels underneath. Holes enlargen and become sinkholes (cenotes) and dozens if not hundreds of unexplored rivers carve the underground of the Yucatan. Underground rivers join, eventually reaching the sea. Many rivers reaching the sea separately. Some as the "rias" mentioned in the above post, some as partially submerged tunnels reaching the sea.
Of course, closer to the sea, the upper portion is fresh water, while the lower portion is salt water. Most life, live in the salt water. Unsure of the technical name, but like a thermoclyne, there is a defined separation layer between the salt and fresh water. Salt water is blurry, while fresh water is clear. If swimming in the fresh water portion, crossing into the salt water causes the waters to mix and vision to become cloudy. Due to large and small hole, almost invisible sinkholes many chambers have that rise above the water level.
From discussion with friends and some google-fu.
Could make an interesting subterranean river system map with exposed sinkholes and of course Mayan ruins/zigurrat pyramids hidden in jungle at various cenotes...
GP
Gamer Printshop Publishing, Starfinder RPG modules and supplements, Map Products, Map Symbol Sets and Map Making Tutorial Guide
DrivethruRPG store
Artstation Gallery - Maps and 3D illustrations
Think it is a Halocline.
[EDIT: checked at wikipedia: http://en.wikipedia.org/wiki/Halocline]
-Rob A>
Last edited by RobA; 09-20-2009 at 11:20 AM. Reason: Checked
My tutorials: Using GIMP to Create an Artistic Regional Map ~ All My Tutorials
My GIMP Scripts: Rotating Brush ~ Gradient from Image ~ Mosaic Tile Helper ~ Random Density Map ~ Subterranean Map Prettier ~ Tapered Stroke Path ~ Random Rotate Floating Layer ~ Batch Image to Pattern ~ Better Seamless Tiles ~ Tile Shuffle ~ Scale Pattern ~ Grid of Guides ~ Fractalize path ~ Label Points
My Maps: Finished Maps ~ Challenge Entries ~ My Portfolio: www.cartocopia.com
GP> Thinking about this one... trying to nut the sucker out and I keep coming back to some stuff that is hard to explain but easy to demonstrate.
Everything has a property called "surface energy" (it's basically the energy required to make surface area)...
If you drop a liquid on a surface (i.e. glass, the kitchen bench, a sink) it reshapes itself to minimise its surface (because more surface = more energy) and the universe likes to minimise energy.
Why does this matter?
Experiment: Get a glass of water, stick a dishcloth in it, drape the dishcloth over the edge of the glass and into the sink. Do the same with another glass but use a NORMAL cloth (any old boring bit of tight-weave fabric)
Expected results: Water climbs the cloth, over the edge of the glass and down the sink. (Note: if you use hot water, it should do it faster). The dishcloth glass should be more empty than the "normal cloth" after say 1 hour.
How the cheese does this relate to sinkholes and the Yucatan?
The ocean is your "sink". The water source is your glass. The two cloths represent the different kinds of land.
Water likes touching water, but it also hates having lots of surface. In the tight-weave cloth you reduce the surface (by making it touch the cloth) BUT more water is touching cloth which it doesn't like much. There is also no nice smooth "water highway" through the cloth. Any water has to move around in a lot of directions to get around the threads.
In the dishcloth, there are lots of nice holes and spaces. Holes = water touching water which is good. Cloth = less surface which is good. Loose weave = clear paths to the other end of the cloth. Hence the water should move faster.
SO back to the Yucatan. Given the options: make a river versus "flow through this swiss-cheese rock stuff" the one that has the least energy involved is the "swiss-cheese rock" AND because there is less energy spent on surfaces, more energy can be spent on moving and hence it is a faster path making sure it meets the requirements of the river police.
Just a side-note for the science inclined amongst us... the REAL fun is observing the water "climbing" the glass when the surface tension/energy minimisation makes it better for the water to climb to the cloth when the cloth isn't touching the water directly than it is to stay where it is.
Expected results: Water climbs the cloth, over the edge of the glass and down the sink. (Note: if you use hot water, it should do it faster). The dishcloth glass should be more empty than the "normal cloth" after say 1 hour.
This is similar to the phenomenon of "super-fluidity" found when you get liquid helium. The end result is the liquid helium running up the sides of a container to drop onto the floor of the cooling-chamber. I've forgotten how far it will climb, but for <5mL of liquid more than about 10cm is HUUUGE. (Points further questions on super-cooled super-fluid helium to our resident CERN-Nerd)
"Sacrificing minions... is there any problem it cannot solve?" - Order of the Stick
- Budding Founder of the Geopolitical Police
- Resident Random Science Nerd
- VTES Geek (http://juggernaut1981.blogspot.com/)
Some of the books I have written, or am still writing...
My Lulu Store
Wow. Just... wow. I admit I cracked up a bit on the original posted map but the thread was a great read, full of awesome information on rivers and really helps me with my issues with them.
I do like the cloth/glass explanation, it does help make sense of that theory.
Posting Permissions
Reply With Quote
