Integrate gravel data from 250m data source into 100m soils gird extraction

[CaitlinA]

There is no gravel data available in the 100m SoilsGrid data.

Per conversation with Travis Nauman, get gravel data from the 250m data source. OK to use with 100m.

META_GEOTIFF_1B.csv.zip

[CaitlinA]

We now plan to use the 250m data in its entirety.

100m data has two issues:

• Assumes all soils are the same length (not true) and no depth to bedrock
• No gravel