Arrange the listed principal soil horizons from top to bottom. A. A horizon B.…
2024
Arrange the listed principal soil horizons from top to bottom.
A. A horizon
B. B horizon
C. C horizon
D. O horizon
E. R horizon
Choose the correct sequence.
Answer: C. D, A, B, C, E — ConceptA soil profile is a vertical section of soil described through master horizons. Each horizon is distinguished by its material and degree of soil…
- A.
A, B, D, E, C
- B.
B, A, C, D, E
- C.
D, A, B, C, E
- D.
C, B, A, E, D
Show answer & explanation
Correct answer: C
Concept
A soil profile is a vertical section of soil described through master horizons. Each horizon is distinguished by its material and degree of soil formation.
Organic material occurs at the surface, mineral horizons follow beneath it, and progressively less-weathered parent material and bedrock occur lower down.
Application
First map each item label to the horizon named in the stem.
Item label | Horizon |
|---|---|
A | A horizon |
B | B horizon |
C | C horizon |
D | O horizon |
E | R horizon |
Start with the O horizon because it is the surface organic layer.
Place the A horizon below O, followed by the B horizon.
Place the C horizon below B because it is weakly altered parent material.
Place the R horizon last because it is consolidated bedrock.
Thus, the top-to-bottom horizon order is O, A, B, C, R. In the item coding, this is D, A, B, C, E.
Contrast
A, B, D, E, C places O below A and B and places R above C.
B, A, C, D, E begins with B and places O below C.
C, B, A, E, D begins with C and places R above O.
Cross-check
Reading upward from consolidated bedrock gives R, C, B, A, O, so reversing it confirms O, A, B, C, R.