Notes for Essay - Lab 8
1. Does anyone have a rough age for the different horizons of the ubc podzols? I'll assume the agriculture a horizon is around or less than 100 years old.
2. Does the glacial till parent material come from glacier movement originating from the north shore mountains or further east?
3. How is the C layer of these soils formed? is basal till, weathering and deposition of bedrock by glacier movement an adequate explanation?
4. Why does rainfall not significantly decrease the pH of these soils? excess rainfall leaches base cations from the soil, increasing the percent of Al3+ and H+, as well as rain being naturally slightly acidic. the pH we got was a consistent 6.5 which is neutral. What is the natural pH of the parent material? is it relatively neutral?
both soil sites were relatively high in organic matter, which is a strong buffer against changes in pH. CEC has that curious ability to retain cations against the percolating effects of water, but gladly releases them to plants. UBC soils are still relatively young (10,000) so a healthy supply of bases are still being released through weathering. and what's being lost is also being continually put back in through leaf litter, crop residues and management practices.
bedrock is not part of the regolith so it's of no consequence for soil formation. transported parent material is everything on top of the bedrock.
glacial till could have been transported on ice sheets over a kilometre high. my guess would be that materials came from here, there and everywhere, and without geological analysis we can't really know origin with much accuracy, but i'm not sure. an awesome question though! what's the age of the mountains vis a vis the glaciation and what would the ice sheet/mountain standoff have looked like???