SMITH, J.
This case is- before us on appeal from a judgment for respondents-, and from an order overruling appellant’s motion for new trial. The -controversy is as to the 'location of the 'quarter section -corner -common to -sections 28 and 33, town-ship 103, range 61,'-in Davison county. The location of this -corner is -decisive of the boundary line of the tract of 1-and in -dispute.
[1, 2] Appellant properly assigns as -error insufficiency of the evidence to sustain the findings andl idotnclusion of the trial- court: First, that the government -corner in -dispute 'was a lost -corner; second, that -upon! 'the facts appellant should be estopped by -acquiescence .and laches from -disputing the location of the' corner -as claimed by respondents. Appellant also assigns -as error an order of the trial court permitting respondents to amend their -answer by pleading an -estop-pel, after the -conclusion- of the trial. The amendment pleaded (constituted a new and independent defense, but was -permitted as conforming th-e pleading to the -eVi-dlence already before the trial court. Appellant’s contention -is that the -evidence received -was not -directed to the defense of estoppel, -and that the amendment, -being -allowed -after the trial, prevented him from,' 'introducing evidence to combat the defense of estoppel and that such -defensa could not have been anticipated!. If it be assum- ' ed that the amendment introduced a new issue, which was- in effect a surprise to -appellant, and that he -wias not then prepared! with necessary and -available evidence to meet -such issue, it was bis -duty so to -adh-ise the trial court and -demand- a postponement of the *560trial for a reasonable time in which to procure and present his evidence. A refusal of a postponement upon a proper and 'sufficient 'showing would have been prejudicial error. The amendment itself was not legally .inadmissible, ibut w,as within the sound discretion of the trial court. Wolfinger v. Thomas, 22 S. D. 57, 115 N. W. 100, 133 Am. St. Rep. 900; Rectenbaugh v. Port Huron Co., 22 S. D. 411, 118 N. W. 697; Hardy v. Woods, 33 S. D. 416, 146 N. W. 568, Ann. Cas. 1916C, 398; Noziska v. Aten, 35 S. D. 451, 152 N. W. 694, Ann. Cas. 1916C, 589. Jn the absence of a demand for and refusal of a postponement of the trial, appellant has not shown prejudicial error in the allowance of - the amendment. The trial court found .as a fact that the quarter corner common to 'sections 28 and 33 as originally placed by the government survey was lost, and' that the corner located by respondent’s survey, Oin a direct line 'between the undisputed section corners' common to sections 28 andl 33, should be accepted as establishing the disputed boundary 'line.
[3, 4] Appellant contends that this finding is against the preponderance of evidence, and we are of the view that appellant is correct in this contention. The quarter corner claimed' by appellant is located1 1.85 chains north of the corner claimed by respondents, which a surveyor established on a direct line and at proper 'distances between the known section corners. The 'rate that this court will not disturb findings1 of a trial count, unlesis the same are clearly against the preponderance of the evidence, is so well settled that a citation of authorities to support it is. unnecessary. Randall v. Burke Township, 4 S. D. 337, 57 N. W. 4; Unzelmann, v. Shelton, 19 S. D. 389, 103 N. W. 646; First Nat. Bank v. McCarthy, 18 S. D. 218, 100 N. W. 14. The regulations governing surveys of public lands require a quarter section corner to' be marked on an east and west line by a mound and) two pits, one east and the other west of such mound. It isi absolutely undisputed that a mound and two pits corresponding ta the government regulations • was •observed, and existed undisturbed!, at or in the vicinity of the point claimed' by appellant, as early as .and since 1885, and until 1912, when it appears to have been, partially obliterated by. plowing or other mean's.
The existence of siuch a córner is shown' by 'an- abundlance Of undisputed evidence. It is conceded that no corner or indication *561of a government quarter comer ever existed on the direct line 'between the section corners. It is undisputed that no¡ other corner or indication of ■ a government corner was ever observed tor found anywhere in the. vicinity of the mound1 and pits claimed' by appellant as the original corner. The 'genuineness of this comer is urn-impeached, save by some slight divergence, in the testimony of the witnesses as to .its exact location', and by the field notes and plat of the 'original survey, which purport to locate the quarter corner on a straight line between the section corners,' and :by the existence of certain early landmarks 'in the way of fences north arid south. Such fences are at different distances east from the corner, and are not themselves in. 'alignment. The record i® silent as to who b'ui'lt them. It is not claimed that they were 'built by appellant. Nearly all of the numerous witnesses, both of appellant and respondents', testified to having seen such a corner as that described by appellant at some time, and we think were substantially agreed as to its ap>pearance and location. The physical existence of such a corner ever since 1885 is, we think, established beyond question, and the clear •preponderance of ithe evidence favors the conclusion that it is an original government corner, erected by the government surveyons who made the survey in 1873, about -12 years before it was first observed iby two of appellant’s -witnesses.
[5] The remaining iqjuestiom of importance is whether the finding -and conclusion of -the trial court, that appellant should be held estopped from1 claiming the i’and in controversy by -reason of laches and acquiescence is sustained by -the evidence. It is clear that -neither pl-ainitiff nor defendants ever intended toi claim any land outside of or beyond the lines established' by the original government survey, or outside of the true boundary line between the'ir respective quarter sections. The only controversy^ is as to' the location of the -quarter section cornet. The question of title by adverse possession for 20 years under the statute is mot involved. As a general rule possession is not adverse when the .parties- intend to claim only as far >as the true line. But the question of adverse possession may be conclusively .determined by the length of time -during which there has been acquiescence in a disputed boundary., When such acquiescence -continues -during- the statutory period prescribed as a bar to re-entry, title may be acquired *562through -acquiescence alone. The rule that the presumption of an agreement fixing ¡a 'division line is conclusive, where both parties have 'been in possession' and use -of their respective ¡lands up to a dividing line marked' by visible objects, such as a fence, is -correlated to the rule of adverse possession, and is distinct from the rule of estoppel, by acts or conduct. Such possession for the statutory period 'barring re-entry is -conclusive!y (presumed' to be adverse, and the right is barred by the statute, without further proof that possession is adverse. Lawrence v. Washburn, 119 Iowa, 109, 93 N. W. 73; Morrow. Hall, 169 Iowa, 534, 151 N. W. 482. Estoppel, however, arises only where by conduct or .acts the adverse party has been induced to alter his position., or toi do that which' he would1 not otherwise have done, and to Ms prejudice. Mere failure to bring an action does nlct create an estoppel. Hubbell v. McCulloch, 47 Barb. (N. Y.) 287; Redd v. McCourt, 41 N. Y. 435. In Hinkley v. Crouse, 125 N. Y. 731, 26 N. E. 452, it is held that where there was no consent to the original taking •of possession, and the right to do so was. .disputed at the time, although no protest was made thereafter fiar a period1 of 10 years, the boundary line did not become established by reason of acquiescence, and in Buchanan v. Ashdown, 71 Hun, 327, 24 N. Y. Supp. 1122, it was: held that each possession must continue'for 20 years to ripen into a title. See, also, Sanford v. McDonald, 53 Hun, 266, 6 N. Y. Supp. 613.
In the case of Keller v. Harrison, 139 Iowa, 383, 116 N. W. 327, plaintiff, the owner of the N. E. ¼ of section 28, brought an action .against the defendant Harrison, owner of the N. W. section 28, claiming that he was about 20 rods east .over the line. The defendant denied that his occupancy was.- .beyond the true ¡boundary, interposed the defense of adverse plossesdioin and acquiescence, and demanded by counterclaim that the title be quieted in him. The court said:
“If plaintiffs -succeeded in proving the location, of the government line where they contended it should :be, then the burden of proof was on defendant to prove that the division dine had been acquiesced in da long .and under such circumstances that it should be accepted as the boundary between the respective tracts.”
Quoting -with approval from its decision in the former case, the court also said:
*563“The -doctrine of acquiescence is founded1 on- the presumption of an agreement fixing the division lin-e from long maintenance -of a fence -or ¡other monument marking -a line as ¡boundary between the adjoining -owners, and this is of such strength that after the lap-se of io years, in the interest of peace and quiet, they are not permitted to gainsay the agreement thus inferred. * * * In the absence -of controlling circumstances, acquiescence in the division line, assumed or established-, accompanied 'by actual occupancy in accordance therewith by the adjoining Owners for a period -equal to that prescribed in the statute -of limitations (io years in Iowa) within which an entry may be barred, is conclusive evidence of ■such an agreement.”
The trial court in the Keller case instructed the jury that:
“It is for you to determine, from all the evidence admitted upon the trial in relation thereto, whether the parities -dii-d in fact acquiesce in and consent to the boundary line, as- claimed by the defendant as being the true boundary line -dividing the respective lands.”
The instruction was -held erroneous-, the court saying th-e jury -should have been told that:
“If -defendant by himself, employes, or tenants, marked by the planting of trees, grove, -o-r other improvements-, a visible division line, in good faith believing it to be the true boundary, and for -more than io years subsequent thereto -occupied and! made use of the land up to such line, and during siu-ch period thie- owners of plaintiffs’ land occupied and cultivated their land up to such line, then they will be conclusively presumed1 to have agreed thereto as a boundary line, and neither party can be heard to sa-y that the 'division line, so marked, is not the true boundary between them.”
See, also, 9 C. J. 240, § 187, and cases -cited.
[6, 8] These -ca-ses illustrate the -distinction between the doctrine of estoppel lb)!- -acts or -conduct within the period! of limitation and mere acquiescence’ in- possession f-o-r the -whole period of -limitation. In this -case the trial court held- that plaintiff iw-as estopped to claim the tract in -dispute .by reason of acquiescence in -defendant’s possession and use thereof from 1900 and laches in the commencement of this action. The facts found by the trial -court upon which the ultimate; conclusion of -estoppel was based, are suib*564stantially: That in 1900 one Tiffany was the owner of the S. W. of secti'on 28, and! in the 'Spring loif that .year (built a fence 'inclosing the -laindi in dispute, and! remained in possession of and .cultivated the same until the commencement of this action in 1914; that during said1' time appellant allowed and acquiesced in such use of the disputed tract; that in 1905 and 1906 appellant himself- built a fence along the north side of the N. ’W. % of section 33, which did not include the tract in dispute-; that a public highway existed and was traveled south of the disputed' corner, and between said lines of fence, since 1890. It also appears in the record that in 1885 and 1886 certain breaking was .done and trees were planted, (by appellant’s predecessors in possession, along the north line of the N. W1. Jd Of section 33, a little south of but in the general direction of the line claimed by appellant; that prior tío 1900, the rdad traveled was north of the trees, but after Tiffany built his fence in that year, the travel Was forced south by the fence and ■ran through a iben'd in the tree rows, leaving some of the trees inside the traveled road, and two or three inside Tiffany’s fence. But the undisputed evidence ©hows’ that appellant at all times contended and insisted that the original government quarter section comer was at the point and 'was identical with the corner contended for by hkn at the trial; that when Tiffany built his fence, inclosing the .disputed tract, appellant pointed1 out to him and claimed this cornier to be the original government corner; that when Herman, .a© owner of the land, started to break sleuth of the corner, appellant protested and1 called his attention to the ©ame cornier, and in fact, whenever any question concerning the location oif the corner arose with any person, appellant asserted that the corner referred to was the original corner. In the entire record there is not a scintilla -of evidence tending to sho'w that appellant ever at any time conceded or agreed that the corner or the lime in dispute was at any other place than that contended1 for at the trial. Neither is there a particle of evidence in the record tending ¡to show that appellant by anything 'he ever did1 or said, induced respondent to do any laet or make any expenditure which could be deemed prejudicial. The fact that appellant suffered respondent to remain in ■possession, of and1 cultivate the disputed strip of land1 for a number of years, and appropriate to his- own use crop© raised thereon, and refrained1 from bringing ejectment, was ¡beneficial rather than prejudicial to respondent. Nor was respondent put to additional *565expense i-n building 1ms 'fence, other or greater than-would1 have been involved, had1 the same been .built on the line contended1 for by appellant. We are of the view that no fact disclosed1 by the record and no act or failure to act on the part of appellant was of such .character as to wtorlc an estoppel. Koontz v. Mylius, 77 W. Va. 499, 87 S. E. 851; Hill v. Collier (Tex. Civ. App.) 135 S. W. 1084; Harris vs. Lewis; 156 Iowa, 413, 136 N. W. 674.
The findings and ooocluision of the trial court upon the question of estoppel are clearly against the preponderance of .the evidence. We have examined1 the other 'assignments1, but find no prejudicial error, and1 they are not of sufficient importance to. wiarrant discussion. The findings of fact, 'conduskmis, andl judgment of the trial court are reversed, and the cause remanded for further pro ceedings according to law.