Gravel and Crushed Rock Types Explained for Excavation (Oregon)

Quick Verdict

Gravel types, explained in plain terms, are easier to keep straight once you know two things: the size of the rock and whether it is "clean" or "minus." A minus product, like 3/4-minus, includes the fine dust that lets it compact into a hard base; a clean product, like drain rock, has the fines screened out so water flows through it. From there the common names make sense: base rock for compacting under driveways and slabs, drain rock for French drains and behind walls, river rock and pea gravel for decoration and paths, pit-run for cheap bulk fill, and sized crushed rock like 1.5-inch for heavy sub-base. In Oregon, Central Oregon basalt-crushed rock and Willamette Valley river-run gravel can carry different names for similar uses, because the local quarry source changes what it is called. This page is the overview; the deeper sibling guides drill into sizes and uses.

The Two Things That Define Any Gravel

Before the names, learn the two properties:

• Size: how big the rock pieces are, from dust-fine up to several inches
• Clean vs minus: a "minus" product keeps the fine material (3/4-minus means three-quarter-inch rock down to dust), while a "clean" product has the fines screened out

Minus products compact into a solid, load-bearing surface because the fines fill the gaps. Clean products stay loose and let water drain through because there are no fines to clog them. Almost every name below is just a size plus one of these two behaviors. For where materials fit in a project, see our excavation materials and hauling guide and the trade overview in our Oregon excavation contractor guide.

The Gravel You Will Hear Quoted

Here is the one-glance table of the common products:

Name	Rough Size	Clean or Minus	Typical Use
3/4-minus	3/4 inch to fines	Minus	Base under driveways, slabs, paths
1.5-inch	around 1.5 inch	Often minus	Heavy sub-base, soft-ground bridging
Base rock	varies, with fines	Minus	Compactable base layer
Drain rock	3/4 to 1 inch+	Clean	French drains, behind walls, dry wells
River rock	rounded, various	Clean	Decorative, ground cover
Pea gravel	small, rounded	Clean	Paths, decorative, pipe bedding
Pit-run	mixed, unscreened	As-dug	Cheap bulk fill

If you remember that minus compacts and clean drains, this whole table follows from the size and the use.

Base vs Drain: The Most Important Distinction

The two workhorses are base rock and drain rock, and confusing them causes real problems:

• Base rock (minus) is for support. It compacts into a hard layer under driveways, slabs, and pavement. Its fines are a feature.
• Drain rock (clean) is for water. It goes in French drains, behind retaining walls, and in dry wells so water can flow through. Its lack of fines is a feature.

Put base rock in a French drain and the fines clog it; put drain rock under a driveway and it never compacts. Each is right for its job and wrong for the other. For a deeper look, see drain rock vs base rock.

The Decorative and Fill Products

Not every gravel is structural:

• River rock is smooth, rounded stone used for ground cover and decoration; it does not compact and is not a base
• Pea gravel is small rounded stone good for paths, decorative areas, and bedding pipe, but it migrates and is not load-bearing for vehicles
• Pit-run is unscreened material straight from the pit, cheap and good for bulk fill where you do not need a specific size

These have their place, but using a decorative product where you need structure, or vice versa, is a common and costly mistake. For the size-by-size breakdown, see crushed rock sizes explained.

The Oregon Source Angle

Here is the local wrinkle: the same product can have a different name depending on the quarry. Central Oregon sits on basalt, so much of its crushed rock is angular crushed basalt, which compacts and locks together well. The Willamette Valley has river systems, so a lot of its gravel is river-run, rounded material that behaves differently. Because suppliers name products by their local source and screening, the exact name you hear in Bend may differ from what you hear in Salem for a similar use. When in doubt, describe the job, "compactable base under a driveway" or "clean rock for a French drain," and the supplier matches the right local product.

How Much to Order: Thinking in Cubic Yards

Once you know which gravel you need, the next practical question is how much, and gravel is sold and hauled by the cubic yard, not the bag or the ton of guesswork. A cubic yard covers a set area at a given depth, so the quantity comes from the area you are covering and how deep the layer needs to be. A thin top dressing over a large area and a deep base over a small one can call for the same amount of rock, which is why estimating by eye usually comes up short. Ordering by the calculated volume, with a little extra for compaction and waste, avoids the cost and delay of a second delivery.

It also helps to remember that gravel compacts. A loose cubic yard dumped on the ground takes up more space than the same material after it is spread and compacted into a base, so a section that needs a certain finished depth requires somewhat more loose rock than the bare math suggests. Suppliers and contractors account for this when they figure quantities, which is another reason to describe the job and let a pro calculate the order rather than guessing. Getting the quantity right the first time keeps delivery costs down, since hauling heavy rock is priced by the load and a short order means paying for an extra trip.

Cost Orientation

Gravel price varies by type, source, and delivery distance. Use these as planning ranges only.

Material	Industry Baseline Range
Crushed gravel / base rock, delivered, per cu yd	$45 - $110+ per cu yd
Drain rock, delivered, per cu yd	$45 - $110+ per cu yd
Pit-run / bulk fill, delivered, per cu yd	$20 - $75+ per cu yd
Decorative river rock / pea gravel, per cu yd	upper end, varies widely
Delivery / haul, per load	$250 - $750+ per load

These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote.

Current Market Reality

Real costs often run higher when the quarry is far from the site, since hauling rock is heavy and distance-driven, and when a decorative or specialty product is specified. Buying the right product the first time is cheaper than redoing a base built from the wrong rock.

The Bottom Line

Gravel names come down to size plus clean-or-minus: minus compacts for base, clean drains for water, and the rest is decorative or fill. In Oregon the local quarry source changes the name, so describe the job and let the supplier match it. Cojo is CCB Licensed and Insured and sources the right rock statewide. See our excavation services and request a free estimate.