Soil series profile

Marine soil series

Marine is a somewhat poorly drained soil with a silt loam surface, mapped on 175,479 acres in 12 counties in IL. Hydrologic group C/D.

#2088 by mapped area fine Aeric Albaqualfs (Alfisols)

Drainage class
Somewhat poorly drained
100% of mapped acres
Hydrologic group
C/D
100% of mapped acres
Typical topsoil pH
6.2
slightly acidic · range 6.2–6.2
Mapped area
175k
acres in 12 counties, 1 state

Typical Marine profile

Texture and pH by depth

Typical Marine soil profile by depth 0 in 20 in 40 in 60 in 0–9 in · Ap · pH 6.2 · 15% clay Silt loam 9–17 in · E · pH 5.5 · 13% clay Silt loam 17–43 in · Bt · pH 5.0 · 39% clay Silty clay loam 43–62 in · BCt · pH 6.2 · 31% clay Silty clay loam 62–77 in · 2C · pH 6.7 · 25% clay Silt loam
Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).
Show as a table
Typical Marine horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–9 in (Ap) Silt loam 6.2 15% 4% 2%
9–17 in (E) Silt loam 5.5 13% 4% 0.3%
17–43 in (Bt) Silty clay loam 5.0 39% 4% 0.5%
43–62 in (BCt) Silty clay loam 6.2 31% 4% 0.3%
62–77 in (2C) Silt loam 6.7 25% 15% 0.2%

Representative values from the most extensive Marine map unit (Marine silt loam, 0 to 2 percent slopes, survey area IL117). Other map units of this series vary within the series range.

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

What this means

What Marine soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Marine soils is slightly acidic: pH 6.2, the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Marine acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (100% of mapped Marine acres).

100% of mapped Marine acres is somewhat poorly to very poorly drained, so soil stays soggy for long spells after rain and in wet seasons. Raised beds, plants that tolerate wet feet, and not working the soil while wet all help.

For lawns and yards

On 100% 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.

A seasonal high water table comes within 18 inches of the surface on 100% of mapped acres, often in spring. Basements, sump pumps and lawns in low spots feel it first.

For a septic system

For conventional septic absorption fields, NRCS rates 100% of the acres in mapped Marine 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 Marine soil is found

Mapped acres

Marine is mapped in Illinois.

Counties with the most mapped Marine soil
County Acres Share of county land
Randolph County, IL 34,957 9.8%
Madison County, IL 31,063 7.0%
Macoupin County, IL 26,485 4.8%
St. Clair County, IL 22,925 5.7%
Washington County, IL 15,906 4.5%
Montgomery County, IL 14,209 3.2%
Monroe County, IL 13,335 5.5%
Bond County, IL 9,842 4.1%
Jackson County, IL 3,262 0.9%
Perry County, IL 2,063 0.8%
Jersey County, IL 1,431 0.6%
Clark County, IL 3 0.0%

Septic absorption fields

NRCS rating, share of Marine acres

Not limited 0%
Somewhat limited 0%
Very limited 100%
Septic tank absorption field rating across mapped Marine acres. Scale 0 to 100% of mapped land.
Show as a table
Septic tank absorption field rating across mapped Marine acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited100.0%

Drainage, water table and flooding

Share of Marine acres

Depth to seasonal high water table
About 1.2 feet (14 in) (median where reported); within 18 inches on 100% of acres.
Flooding
Not mapped as flooding on most acres.
Slope
Typically 1–4% (median 1%).
Topsoil organic matter
Median 2%.

Drainage class

Excessively drained 0%
Somewhat excessively drained 0%
Well drained 0%
Moderately well drained 0%
Somewhat poorly drained 100%
Poorly drained 0%
Very poorly drained 0%
Drainage class across mapped Marine acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Marine acres.
CategoryShare of acres
Excessively drained0.0%
Somewhat excessively drained0.0%
Well drained0.0%
Moderately well drained0.0%
Somewhat poorly drained100.0%
Poorly drained0.0%
Very poorly drained0.0%

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) 0%
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 100%
Hydrologic soil group across mapped Marine acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Marine acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration0.0%
D: very slow infiltration (clayey, shallow or wet)0.0%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained100.0%

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 Marine (component kind "Series") in SSURGO: 175,479 acres.
Method
Shares are by mapped acres of Marine components. The profile comes from the single largest Marine component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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