You can breed 2 earth dragons together or you have to spend 75 dragoncash in the eggs section of the market
Earth Dragon and Cold Dragon
Breed the earth dragon with the fire dragon.
ice dragon+Earth dragon=Mountain dragon
There is no "marsh" dragon in dragonvale but if you are referring to the moss dragon the best way to get it is earth and plant, although you also have a chance to breed the tree dragon.
To breed a iron dragon you use a metal dragon and earth dragon to breed your chances will be 100% chance at getting one.
You don't breed a Kairos Dragon in DragonVale. You have to get parts to complete it.
You breed fire and earth dragons though sometimes you might get a lava dragon instead!!
You can't breed a Bone Dragon after Halloween. To breed a Bone Dragon: Fire and Earth Dragon (level 10)
you breed a ice dragon with a mine dragon
When you breed an earth and firefly dragon, you can get a crystal, scorch, sandstorm, or firefly dragon.
You have to breed a plant and a fire dragon.
As of July 2012, there has not been a star dragon in DragonVale.