Hi Jerry,

Thank you for reaching out to Ask Extension!

Soil "composition" will vary greatly throughout our region. It can even vary greatly from one area of your yard to the other. There is not one specific soil type in the Denver area. If you are interested to know what your soil consists of, consider having a soil test done. Here's more info about soil testing: https://planttalk.colostate.edu/topics/soils-amendments-composting/1606-soil-tests/ Here is where you can submit a soil sample for testing: https://agsci.colostate.edu/soiltestinglab/

You can have a soil test done here: https://agsci.colostate.edu/soiltestinglab/

The ideal soil will consist of 25% air, 25% water, 1-5% organic matter and 45-49% mineral solids. The soil texture is determined by the amounts of sand, silt and clay in the soil from the mineral and organics, and these along with fertilizers is where the nutrients come from.

Here is more information about soil in general:

https://cmg.extension.colostate.edu/Gardennotes/211.pdf

Here is more information about the texture of soils:

https://cmg.extension.colostate.edu/Gardennotes/214.pdf

You did not mention why you needed top soil. Was it for a raised bed, or to fill in holes in your yard or for grading? Was it to ammend your soil or for a project like a new lawn?

Here is more information about using soil ammendments in Colorado for you also:

http://extension.colostate.edu/topic-areas/yard-garden/choosing-a-soil-amendment/ 

I hope this helps!

Dawn