In an attempt to break out of my genre comfort zone, I am doing a full-fledged parallel world fantasy for NaNo this year.  I'm currently designing the geography, and I would really appreciate some help.  I've never designed a parallel world before, at least not one where I tampered with the structure of the earth surface itself.  Below is pasted what I have thus far for world development.  What do you think of it?  Do you see any logic holes or inconsistencies?  Is it interesting?  Is it believable?  I know I don't have to abide by strict science, but I don't want to overextend the reader's suspension of disbelief.  Please tear this apart, if you have a moment!  Thanks much.
Quote:
STRUCTURE
The earth is flat.  It is a solid plate of rock averaging about a mile thick.  It does not spin or rotate, and it has neither sun nor moon.  The only other points in the sky are tiny green dots that are speckled across the space below the earth; they are either very small or very distant, and no one knows what they are.
In the morning, the sky is light and gleams rich robin’s egg blue.  It slowly fades into black as the day wanes, only to be born again the next day.  The light does not gradually rise; at promptly 6am, it explodes suddenly like a light bulb being turned on.  There is no need for time zones.
CLIMATE
There is no direct source of light in the sky to give heat and vary the climate.  Rather, climate on the surface is determined by the elements that burn beneath the earth.  On the underside of the rock are pools of fire in the south and glaciers of ice in the north, which spaces of bare rock in between.  
Wind blows from the center of the bottom of earth in both directions, wrapping up and around.  In the south, wind blows past the fire and carries warm air across the surface, gradually cooling as it nears the middle; in the north, wind blows past the ice and carries cold air across the surface, gradually warming as it nears the middle.  Therefore, the southern extremes of the earth are hot while the northern extremes are cold, with various milder temperatures in between. 
Clouds only form prior to rainstorms.  In the south, clouds are wispy and lilac in color.  Precipitation is infrequent, and it is generally in the form of a light mist.  In the north, clouds are puffy and a light orange in color.  Precipitation is more common, coming in the form of snow or hail in the colder regions and thunderless storms of fat drops in the milder regions.  In the center, where the northern cold front meets the southern warm front, the clouds come in flat, smooth sheets of metallic silver.  Precipitation is frequent; a few mild regions in this area are blessed with good, moderate rainfall, while the extremes experience terrific storms of lightning and tornadoes.  In all regions, the thicker the clouds are, the more precipitation they carry; as they drop their moisture, the clouds fade to white before dissipating.
The heavy rainfall in the center regions feeds rivers that flow to the north and south.  When a river reaches the end of the land, it literally cascades over the edge of the earth in a spectacular waterfall, where it evaporates back into the air.  In the extreme south, the fire causes the overflow of some rivers to evaporate into dangerous steam; in the extreme north, the waterfalls are often half-frozen.
Because the earth does not rotate, weather is constant and varies little within a region.  There is no change of season.  Each region has specific climatic circumstances which give it a unique flora, fauna, and culture.