Large River Rock in Pennsylvania: 2 to 4 Inch Rounded Stone

On the high plateau of the Northern Tier, water comes off the valley sides fast and arrives somewhere in a hurry. That is the situation most readers of this page are in: a bed, a splash area or a channel where smaller cover has been picked up and moved, and a choice to make between the standard river rock size and this one. The difference is weight per piece, and weight per piece is what decides whether a stone stays where you put it.

Two to four inches, water worn, tans through gray and brown

The specification is short and it is worth taking literally.

Rounded means it was shaped by water rather than by a crusher, so there are no sharp faces. That is the character of the material: pieces that sit against each other rather than locking together, and a surface that reads as settled rather than as construction. It also rolls under anything with weight on it, which rules out a set of jobs further down this page.

At two to four inches each piece has real mass, enough that a stone at the top of the range is a two-hand lift and enough that moving water has to work much harder to shift it than it does with a one to three inch cobble.

Five jobs on a plateau property, scored for large river rock

Where a bed is being covered rather than featured, River Rock at one to three inches is the easier stone to live with. The larger size earns its place where water moves, where a border needs to read heavier, or where a feature has to hold its own against a big planting.

What runoff off steep valley sides does to loose cover

The plateau drains fast. Rain and snowmelt run off steep valley sides and concentrate into narrow valleys, roadside ditches, culverts and low drives, and extreme rain or rain falling on snow is when that flow is at its worst.

Two consequences for a decorative stone. Anything in the path of that flow has to be heavy enough to stay, and mulch, chips and small cobble will not be. And the channel shape matters more than the stone: a dry creek line cut with a proper fall sends water somewhere, while the same stone scattered across bare ground just gets rearranged.

There is a limit to what this material is, and it is worth being plain about it. Two to four inch rounded stone is decorative and light erosion work. Armoring a stream bank or a culvert outlet where water has force behind it is a RipRap job, sold locally by R-number, with R-4 for ditches and the larger R-5 to R-7 sizes for banks and streambanks.

The garage pad on the list, and why it gets a different stone

A shed or garage pad is a compaction problem, and rounded stone answers it badly. A pad needs a layer that locks together under a compactor and carries a point load without moving, which means angular material: 2A Modified for a compacted base, or #57 Stone as the open drainage layer beneath a slab. Under a slab, cobble shifts; under a wheelbarrow wheel it rolls; and it cannot be made level in any lasting way.

Keep this stone for the bed beside the pad, the splash area at the downspout corner, or the edge where the pad meets the lawn.

Yards and tons for a 30 foot creek line and a splash apron

Hypothetical examples. Square feet times depth in feet, divided by 27 for cubic yards. The site does not publish a weight for this size specifically, so these use the nearest listed family on its calculator pages, river rock at about 2,700 lb per cubic yard or roughly 1.35 tons per yard. Treat the tonnage as approximate.

Depth is the thing people get wrong with a big cobble. Below about four inches the stones sit as a single scattered layer and the fabric shows through the gaps; four to six inches is where a bed or a channel looks filled. That also means a cubic yard does not go far: at 5 inches it covers roughly 65 square feet. The river rock calculator will run your own dimensions.

Where a load of two to four inch stone can be dropped

This is heavy, bulky material and it does not wheelbarrow well, so the drop spot is a real decision rather than an afterthought. Pick firm standing as close to the work as the truck can safely reach, with clear overhead room and space to pull away, which on a hill lot usually means the drive. Work out the route from the pile to the bed first, because rolling stones a few feet is easy and wheelbarrowing them forty is not, and a tarp under the drop spot makes the last of the pile easier to lift off.

Have the channel cut, the fabric laid and the edging set before delivery. Placing large cobble is the quick part of the job when everything under it is ready.

Set your quantity and delivery date on this listing. Delivery is arranged at checkout by ZIP code, and anything awkward about the approach is better raised with Pennsylvania Rock Supply through Contact before the date than on the morning.