rock armour

rock armour (countable and uncountable, plural rock armours)

1. (British spelling) Rock or other suitable material used to protect shorelines, streambeds, bridge abutments, pilings and other structures against scour and water, wave, or ice erosion.
   • 2019, Alan Staniforth, Cleveland Way, page 86:

     Walk along the beach to where the rock armour begins, then join the sea wall[.]

   • 2020 August 26, Andrew Mourant, “Reinforced against future flooding”, in Rail, pages 59–60:

     Rock armour was first used on the line "in a very small way" after floods in 2005, and more extensively last year when an embankment had to be reinstated. "The destructive problem with flooding is when water washes over the railway and runs down the other side," explains Hinshelwood. "If it keeps coming, it starts to accelerate, to scour and create turbulence, picking up ever-larger material the faster it washes across. You can't stop it, but rock armour slows it to a point where it doesn't wash ballast or embankment material away."

• rock armor