Sub-Surface Diagnostic Horizons

Question 1

Histic

Answer 1

• O horizon

- very high in organic content, wet during some part of the year

Question 2

Melanic

Answer 2

• A horizon

- thick, black, high in organic matter, common in volcanic ash soils

Question 3

Mollic

Answer 3

• A horizon

- thick, dark-colored, high base saturation, well-developed structure

Question 4

Ochric

Answer 4

• A horizon

- very light colored, too low organic content or thin to be mollic, may be hard and massive when dry

Question 5

Umbric

Answer 5

• A horizon

- similar to mollic but low base saturation

Question 6

Argillic

Answer 6

• Bt horizon

- silicate clay accumulation

Question 7

Cambic

Answer 7

• Bw or Bg

- Altered by physical movement, structure development, or by chemical reactions, generally nonilluvial

Question 8

Kandic

Answer 8

• Bt horizon

- accumulation of low-activity clays

Question 9

Natric

Answer 9

• Btn

- argillic, high in sodium, columnar or prismatic structure

Question 10

Oxic

Answer 10

• Bo

- highly weathered, primarily mixture of Fe, Al oxides and non-sticky-type silicate clays

Question 11

Spodic

Answer 11

• Bh, Bs

- organic matter, Fe and Al oxide accumulation

Question 12

Fragipan

Answer 12

• Bx horizon

- brittle pan, usually loamy textured, dense, coarse prisms

Question 13

Calcic

Answer 13

• Bk horizon

- accumulation of carbonates of calcium and/or magnesium