Soil series profile

Thunderbird soil series

Thunderbird is a well drained soil with a cobbly clay loam surface, mapped on 681,537 acres in 12 counties across 3 states. Hydrologic group D.

#355 by mapped area fine Aridic Argiustolls (Mollisols)

Drainage class: Well drained
Hydrologic group: D
Typical topsoil pH: 7.2
Mapped area: 682k

Typical Thunderbird profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

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Typical Thunderbird horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–3 in (A)	Cobbly clay loam	7.2	31%	35%	1.5%
3–12 in (Bt)	Clay	8.2	48%	23%	1.5%
12–23 in (Btk)	Clay	8.2	48%	23%	1.5%
23–25 in (R)	Unweathered bedrock	Not reported	Not reported	Not reported	Not reported

Representative values from the most extensive Thunderbird map unit (Thunderbird cobbly clay loam, 0 to 15 percent slopes, survey area AZ635). Other map units of this series vary within the series range.

Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Thunderbird soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Thunderbird soils is neutral: pH 7.2 (most land between 7.2 and 7.6), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 98% of mapped Thunderbird acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is cobbly clay loam (53% of mapped Thunderbird acres).

>99% of mapped Thunderbird acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On >99% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

For a septic system

For conventional septic absorption fields, NRCS rates >99% of the acres in mapped Thunderbird soils very limited, 0% somewhat limited and 0% not limited.

Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Thunderbird soil is found

Mapped acres

Thunderbird is mapped in Arizona, New Mexico and Nevada.

Counties with the most mapped Thunderbird soil
County	Acres	Share of county land
Apache County, AZ	186,374	2.8%
Coconino County, AZ	171,009	1.5%
Yavapai County, AZ	104,657	2.5%
Navajo County, AZ	95,653	1.7%
Gila County, AZ	38,610	2.9%
Mohave County, AZ	21,602	0.3%
Lincoln County, NV	21,246	0.4%
Catron County, NM	19,845	0.9%
Mora County, NM	9,647	0.7%
Sierra County, NM	6,904	0.3%
Colfax County, NM	4,480	0.2%
Socorro County, NM	1,512	0.0%

Septic absorption fields

NRCS rating, share of Thunderbird acres

Not limited 0%

Somewhat limited 0%

Very limited >99%

Not rated <1%

Septic tank absorption field rating across mapped Thunderbird acres. Scale 0 to 100% of mapped land.

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Septic tank absorption field rating across mapped Thunderbird acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	99.6%
Not rated	0.4%

Drainage, water table and flooding

Share of Thunderbird acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 4–28% (median 8%).
Topsoil organic matter: Median 1.5%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained >99%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Not rated <1%

Drainage class across mapped Thunderbird acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Thunderbird acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	99.6%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%
Not rated	0.4%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 0%

C: slow infiltration 0%

D: very slow infiltration (clayey, shallow or wet) >99%

A/D: D as is, A if drained 0%

B/D: D as is, B if drained 0%

C/D: D as is, C if drained 0%

Not rated <1%

Hydrologic soil group across mapped Thunderbird acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Thunderbird acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	99.6%
A/D: D as is, A if drained	0.0%
B/D: D as is, B if drained	0.0%
C/D: D as is, C if drained	0.0%
Not rated	0.4%

Sources & data dates

Source: USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
Data date: SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
Scope: All map unit components named Thunderbird (component kind "Series") in SSURGO: 681,537 acres.
Method: Shares are by mapped acres of Thunderbird components. The profile comes from the single largest Thunderbird component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Thunderbird.