Lava rock is the output of melted rock from volcanoes that has cooled down. The natural colors range from dark reddish to deep brown and black. Smaller rocks are used for a permanent mulch while larger ones are available as prominent landscaping features. Once one that is several feet in diameter is set down on the ground it is unlikely to move anywhere. Intermediate-sized lava rocks, though, are light enough that frost heave -- or the ground buckling under winter ice pressure -- may force them out of the ground. Anchoring the rock into the ground prevents this.
Items you will need
- Lava rock
- Electric drill with 1/4-inch carbide bit
- 2, 12-inch long and 1/4-inch diameter steel rods
- Contact glue
Dig a 6-inch depression in your yard, just large enough to set the widest position of the lava rock into.
Dig two, 1-inch wide, 6-inch deep and 10-inch long trenches on opposite sides of the depression.
Set the lava rock on a smooth surface, such as a driveway, resting on the side that will go into the depression. Mark two points 2 inches from the bottom, one on the opposite side from the other.
Drill 1/4-inch holes 3 inches deep into the rock on the marks.
Swab an end of each rod with contact glue and insert the glued ends into the holes. Let them dry.
Set the lava rock into the depression, with the rods fitting into the side trenches.
Cover the trenches and plant grass seed or replace the sod.
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