What is the test for establishing an agreed boundary line?

In Mello v. Weaver, 36 Cal.2d 456, 460, 224 P.2d 691, it was held that agreement to locate a boundary line need not be express, but it may be implied from long acquiescence; that the implied agreement must have been based on a doubtful boundary line; that a dispute or controversy is not essential but it may be evidence of an existence of a doubt or uncertainty; that it is not required that the uncertainty should appear from the deed or from an attempt to make an accurate survey from the calls in the deed; that a doubt may arise from a believed uncertainty which may be proved by direct evidence or inferred from the circumstances surrounding the parties at the time when the agreement is deemed to have been made, and if in good faith the parties resolve their doubt by the practical location of the common boundary it will be considered the boundary called for in the deed.

In Shelton v. Malette, 144 Cal.App.2d 370, 374, 301 P.2d 18, it was held that the true location of the survey of a tract of land is a question of fact and in boundary disputes, monuments control over courses and distances and where the circumstances warrant it, fences have been considered as monuments; that to establish an agreed boundary line there must be an actual designation of the line upon the ground and occupation in accordance therewith; that to make the agreement binding, occupation in accordance with the line so fixed must be acquiesced in by the parties for a period equal to that fixed by the statute of limitations, or for such a length of time that the parties ought not to be allowed to deny its correctness; that such an agreement is conclusive of the correctness of the line and a fence may establish or mark the true boundary line between

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In York v. Horn, 154 Cal.App.2d 209, 211, 315 P.2d 912, it was held that such an agreement and uncertainty in the location of the boundary line may be deduced from the circumstances and may be inferred from the conduct of the [161 Cal.App.2d 749] parties, particularly from long acquiescence; that the fact that an accurate survey is possible is not conclusive of the question of whether a doubt exists as to the location of the boundary and that in order to invoke the doctrine of agreed boundaries all that need be shown is lack of knowledge by both parties where the fence line should be drawn.