Soil survey area

Dinosaur National Monument, Colorado and Utah

Survey Area CO692• Colorado

The short version

The most common soil here is Torriorthents, on about 8% of the land. Ustorthents and Borolls come next.

About 80% of the land drains well.

USDA rates 89% of the land very limited for a standard septic drain field, and 88% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: bedrock lies within 40 inches under 82% of it.

Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.

The ground underfoot

The soils you're most likely standing on

The biggest named soils in Dinosaur National Monument, Colorado and Utah, each drawn five feet deep from its official USDA description, in its recorded colors.

Pensore

4% of the area

Gravelly loam topsoil · well drained

A balanced mix that crumbles in your hand. The gardener's ideal.

Inceptisols

Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.

The biggest mapped areas

The dominant drainage class is Well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Entisols — young soils with little profile development, often on floodplains or steep slopes. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Dinosaur National Monument, Colorado and Utah. Search your address to find the exact soil composition, drainage, and series details at your specific location.

Soil Map Unit	Acres	Drainage	Hydro Group	Dwellings	Septic
Rock outcrop, Torriorthents, and Ustorthents soils, 25 to 75 percent slopes, rubbly	51K	Well drained	D	Very limited	Very limited
Rock outcrop	14K		D	Very limited	Very limited
Cragnot-Pensore-Grapit association, 6 to 75 percent slopes, very stony	14K	Well drained	B	Very limited	Very limited
Ustorthents, frigid-Borolls complex, 25 to 75 percent slopes, rubbly	12K	Well drained	C	Very limited	Very limited
Rock outcrop-Ustochrepts-Cryochrepts complex, 50 to 90 percent slopes, extremely stony	11K		D	Very limited	Very limited
Rock outcrop-Hackling complex, 10 to 45 percent slopes, very stony	8K		D	Very limited	Very limited
Arches-Mespun-Rock outcrop complex, 4 to 40 percent slopes	7K	Excessively drained	D	Very limited	Very limited
Strych-Mellenthin complex, 3 to 45 percent slopes, very bouldery	7K	Well drained	A	Very limited	Very limited
Cortyzack-Duffymont, rubbly complex, 3 to 25 percent slopes	5K	Well drained	B	Somewhat limited	Somewhat limited
Stout-Rock outcrop complex, 5 to 35 percent slopes, very stony	5K	Somewhat excessively drained	D	Very limited	Very limited
Pensore-Lodore-Rock outcrop complex, 3 to 45 percent slopes, very stony	4K	Well drained	D	Very limited	Very limited
Pensore-Roto complex, 3 to 45 percent slopes, very stony	4K	Well drained	D	Very limited	Very limited
Strell-Rock outcrop-Marthaspeak complex, 3 to 45 percent slopes	4K	Somewhat excessively drained	D	Very limited	Very limited
Holter-Detra family complex, 3 to 25 percent slopes, extremely stony	4K	Well drained	C	Very limited	Very limited
Splimo-Chew-Rock outcrop complex, 10 to 50 percent slopes, extremely flaggy	4K	Well drained	D	Very limited	Very limited
Rizno-Windcomb-ThumbRock complex, 3 to 25 percent slopes, extremely flaggy	3K	Well drained	D	Very limited	Very limited
Schoonover-Duffymont complex, 3 to 25 percent slopes, rubbly	3K	Well drained	D	Very limited	Very limited
Mantlemine loam, 1 to 8 percent slopes	3K	Well drained	B	Not limited	Somewhat limited
Lakebench-Yampa complex, 5 to 30 percent slopes, very stony	3K	Well drained	A	Very limited	Very limited
Water	3K			Not rated	Not rated

Soil Orders in This Area

The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Aridisols

Dry-climate soils with low organic matter. Often have caliche layers that make excavation difficult. Low shrink-swell is good for foundations.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

What This Means

Building & Foundations

About 88% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes. A geotechnical assessment is recommended before building.

Septic Systems

About 89% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

Gardening & Agriculture

Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.