The Law Code of Bṛhaspati 1.19.9

1.19.9

sthalanimnanadīsrotaḥ śaragulmanagādayaḥ /
prakāśacihnāny etāni sīmāyāṃ kārayet sadā //

Wells, tanks, pools, large trees, gardens, temples, mounds, channels, the course of a river, reeds, shrubs, or piles of stones:

By such visible signs as these a boundary line should always be caused to be marked; also, by other (marks) deposited underground which the earth is not likely to destroy.