Day Seventy-Seven: On the Multnomah University Campus for HazMat Training :)

Above-Ground Tree Roots....Interesting

This seems to be common with Maples.  

Trees have shallow roots. The vast majority of a tree’s roots are located in the top 12 to 18 inches of soil.  As the tree roots grow, some of the larger roots near the soil surface may emerge from the ground. While many individuals regard surface roots as unwelcome, they are normal for many trees. 

It’s usually best to ignore surface roots as much as possible. (Granted, mowing around surface roots can be tricky.) Covering the area around the tree with 1 to 2 inches of soil provides only temporary relief. The tree roots will continue to grow and will probably reappear in a few years. Placing 4 or more inches of soil around a tree may damage or destroy it by depriving some of the tree’s roots of oxygen.  

 Source:  https://hortnews.extension.iastate.edu/faq/there-are-several-large-surface-roots-around-my-maple-tree-can-i-safely-cover-these-roots-soil