Different species of wood, different humidity, different amounts of sun, different amounts of rain, different amounts of heat, different types of mold, algae and bacteria growing on the wood. I know that ties in a damp area with very acidic soil will last way shorter than ties in a very dry area. A wood barn can stand for 50 years in Nebraska and a fence will rot away in a decade on the Gulf coast.
Dave H. Painted side goes up. My website : wnbranch.com
The weather itself
The use of preservatives can also alter the colors of weathered wood.
Have fun,
Richard
Different species of trees, and different minerals present in the soil, will produce different colours of wood. Fresh wood from local trees will also be different in the two regions you mention.
Dave
In north Texas, wood weathers to a dark or medium grey, and sometimes to a light almost silver color. In southwestern Colorado where we go camping, wood weathers to a deep brown, sometimes with gold or amber highlights.
What causes the difference in color?