This case involves a dispute as to whether strip mining rights were reserved by certain Ohio landowners who conveyed four tracts of land to the federal government some years ago. In a decision reported at 763 F.Supp. 1411 (S.D.Ohio 1991), the district court determined that the grantors of three of the tracts *991did reserve such rights and that the grantor of the fourth (a 5,763 acre tract known as the Culbertson property) did not. We find no error in these determinations. Contrary to a conclusion reached by the district court with respect to the Culbertson tract, however, we conclude that the Department of the Interior possessed authority to reconsider an administrative determination wherein the agency had erroneously recognized the existence of private strip mining rights in that tract. We shall therefore reverse the judgment of the district court insofar as it allowed private strip mining on the Culbertson tract. The judgment will be affirmed as to each of the other tracts.
I
Under the authority of the Weeks Act of 1911, as amended, 16 U.S.C. §§ 515 et seq., the Secretary of Agriculture has purchased many thousands of acres of land in Southeastern Ohio’s coal country for inclusion in the Wayne National Forest. In some of these purchases all mineral rights were included. In order to acquire more acreage for less money, however, the government often made purchases that were subject to a reservation of mineral rights by the grantor. (Land can cost significantly more with mineral rights than without, of course, if there is thought to be any possibility that the mineral rights might be exploitable.) Mineral rights of one sort or another were reserved by the grantors of each of the four tracts at issue here, and the plaintiffs (referred to collectively as “Belville”) eventually acquired the reserved mineral rights pursuant to deed, land contract, and option agreement.
The first of the four tracts to be purchased was the largest: 5,763.14 acres of land in Lawrence County, Ohio, acquired under two deeds executed by E.S. Culbertson and Alice C. Culbertson, husband and wife, on February 26, 1936. The stated consideration totaled $26,697.27, or about $4.63 per acre. Both of the deeds contained provisions reserving to the Culbertsons “the right to prospect for, mine, remove and/or produce coal, oil, [and] gas for a period of 99 years.... ” Other provisions will be described in the next part of our opinion.
In 1942 the government purchased 306.42 acres of land in Scioto County, Ohio, from Edward W. Bauer and Clarice Bauer, his wife, at a stated price of approximately $6.25 per acre. The Bauers reserved for a 99 year period “the right to prospect for and mine by means other than hydraulic ... coal, limestone, clays and shales of Ohio.... ”
By deed dated March 15, 1943, Harmon and Anna Simmering and three couples named Taylor granted the government 1,630.74 acres of land in Scioto County, Ohio, in consideration of -a stated price of $10.00 per acre. The deed contained a reservation of mineral rights similar to that in the Bauer deed.
In March of 1950, finally, a tract of 115 acres in Lawrence and Jackson Counties, Ohio, was granted to the government at a price of $11.00 per acre by Charles A. Jenkins and Beulah Jenkins, husband and wife. Subject to a right of renewal for five years, the grantors reserved “until the termination of December 31, 1989, the right to take and remove coal, clay, limestone, gas and oil.... ”
Strip mining for coal did not begin in Ohio until 1914, the district court found. By 1936, however — the year of the Culbertson conveyances — strip mining accounted for about 10 percent of Ohio’s total production of coal. See 763 F.Supp. at 1413. Strip mining accounted for more than half the total coal production in Ohio by 1948. Id.
During the 1950s, the record indicates, strip mining operations were conducted on both the Bauer and Simmering tracts pursuant to permits issued by the United States Forest Service. Strip mining was conducted on the Jenkins tract, under Forest Service permit, during the 1960s.
Congress subsequently enacted the Surface Mining Control and Reclamation Act of 1977, 30 U.S.C. §§ 1201-1328, a statute known by the acronym “SMCRA.”' Section 522(e) of SMCRA, 30 U.S.C. § 1272(e), provides that “[a]fter August 3, 1977, and subject to valid existing rights[] no surface coal mining operations except those which exist on August 3, 1977, shall be permitted ... on any Federal lands within the boundaries of *992any national forest----” (Emphasis supplied.)
The administrative body charged with responsibility for making determinations as to “valid existing rights” (known to the cognoscenti as “VER”) is the Interior Department’s Office of Surface Mining, Reclamation, and Enforcement (“OSM,” for short). In September of 1985 plaintiff Belville applied for a determination that it possessed valid existing rights to conduct strip mining operations on the four tracts described above. OSM denied the application. Belville reapplied in August of 1988, submitting supplemental information. On December 23, 1988, OSM’s Assistant Director for Eastern Field Operations signed a short letter in which he said it was his determination that Belville “possess[es] valid existing rights” in the four tracts. The letter, sent to Belville with a copy to the Ohio Division of Reclamation, went on to say that Belville could now seek state permits to mine the properties.
In June of 1989, while applications for state permits were pending, a Congressional subcommittee issued a report highly critical of this particular VER determination. Two months later, before the necessary strip mining permits had been issued by the State of Ohio, a newly appointed Director of OSM notified Belville that the VER determinations were being suspended. On December 15, 1989, OSM reversed its determination as to the Culbertson tract. Reversals as to the other three tracts followed some months later.
Belville filed the present action in February of 1990. The complaint sought declaratory and injunctive relief against the United States and various federal agencies and officials. The district court conducted a four-day bench trial in the spring of 1991, and the decision referred to at the outset of this opinion was issued soon thereafter.
The government perfected a timely appeal. Belville cross-appealed from the portion of the decision in which the district court found that the grantors of the Culbertson tract had not reserved (and Belville had not acquired by deed) the right to strip mine coal on that tract. On motion by the government we stayed the judgment pending resolution of the appeals.
II
The validity of Belville’s assertion that a right to strip mine coal was included in its bundle of reserved rights must be determined under Ohio law. Most of the Ohio decisions relevant in this connection deal with conveyances made in an era when coal was extracted only through deep mining techniques, as opposed to surface mining techniques1 — and it is helpful, in reading the caselaw, to bear in mind what mining techniques were in use when the conveyance in question was made.
The time factor has direct relevance to the objective that the Ohio courts are attempting to achieve: ascertainment of the true intent of the parties to the conveyance, as evidenced by the language they used. Intent, in Ohio law, is paramount, and the intent manifested in a given conveyance may be difficult to discern without knowing the time frame in which the conveyance was made.
In the days when underground mining was all there was, Ohio courts developed a strong presumption that a landowner who granted a mineral lease would not have intended to allow the lessee to undermine the surface to such an extent as to produce cave-ins or similar surface disturbances. See, for example, Burgner v. Humphrey, 41 Ohio St. 340 (1884), a deep mining case the first syllabus of which held as follows:
“If the owner of land grants a lease whereby he conveys all the underlying mineral coal, with the right to mine and *993remove the same, the lessee will not be entitled to remove the whole of the coal without leaving support sufficient to maintain the surface in its natural state, unless the language of the instrument clearly imports that it was the intention of the lessor to part with the right of subjacent support.”
In Ohio Collieries Co. v. Cocke, 107 Ohio St. 238, 140 N.E. 356 (1923), another case that did not involve the assertion of a right to strip mine, the Ohio Supreme Court read Burgner as making the holder of the mineral estate strictly liable for damage to the surface, absent a clear showing that the parties had a contrary intent. Rejecting an argument that the grant of a right to mine at will impliedly granted immunity from liability for damage to the surface, the Ohio Supreme Court said that “the rule announced in Burg-ner v. Humphrey, supra, must prevail, and the intention of the party to part with the right of subjacent support must be shown by express grant, or be clearly imported in the instrument conveying the estate.” 107 Ohio St. at 253, 140 N.E. at 361. As the court held in the second paragraph of its syllabus in Cocke,
“A sale of all the coal under a tract of land is not, in terms or by necessary implication, a release of the right to surface support, but such waiver must appear by express grant, or the instrument conveying the estate clearly import such release.”
In 1974 — by which time strip mining had become the predominant method of extracting coal in Ohio — the Ohio Supreme Court had occasion to consider a grant of mineral rights made in 1901, more than a decade before there was any strip mining in the state. In this case, Skivolocki v. East Ohio Gas Co., 38 Ohio St.2d 244, 67 O.O.2d 321, 313 N.E.2d 374 (1974), the court considered for the first time whether the grant of a mineral estate (here a grant of “all the coal in and under” a described parcel) implicitly included the right to strip mine for coal. The Ohio Supreme Court answered, in Skivo-locki, that strip mining rights were not included, the parties to the deed not having manifested an intent that such rights should be included.
The analysis followed by the Ohio court in Skivolocki shows that the intent of the parties must be determined on a case-by-case basis. The task of the courts is one of “trying to ascertain the intent of the parties [with respect to the right to strip mine] at the time the deed was drawn,” 38 Ohio St.2d at 248, 67 O.O.2d at 325, 313 N.E.2d at 377— and the relevant circumstances will vary, obviously, from case to case. Two salient facts were particularly helpful in illuminating the intent of the parties in Skivolocki: “the 1901 deed is coached [sic] in language particularly applicable to deep mining, and the evidence shows that the technique of strip mining was not known in Guernsey County [where the Skivolocki land was located] until 1917.” Id. at 251, 67 O.O.2d at 329, 313 N.E.2d at 378. “Because strip mining is totally incompatible with the enjoyment of a surface estate,” the Supreme Court declared against this background, “a heavy burden rests upon the party seeking to demonstrate that such a right exists.” Id. The Court went on to say that “[t]his is especially true when the deed relied upon was executed prior to the time strip mining techniques became widely employed.” Id. at 251, 67 O.O.2d at 329, 313 N.E.2d at 378-79.2 Considerations such as these have an obvious bearing on the proper resolution of the issues presented in the ease at bar.
The Culbertson Tract
The instruments delineating the mineral estate in the Culbertson tract, like the deed at issue in Skivolocki, contain language “peculiarly applicable to deep mining tech-*994ñiques.” Numbered paragraph three of the Culbertson deeds reads as follows:
“In new development work and operations, all reasonable and usual precautions required by the general mining laws for the support of the surface, will be made and to this end tunnels, shafts and other workings will be subject to inspection by the Forest Officer in charge and by mine inspectors of the United States.”
The paragraph that immediately precedes this one reads as follows:
“In prospecting for, and in mining or removing said coal, oil and gas and in manufacturing the products thereof, only so much of the surface as is reasonably necessary for the purpose, shall be used.”
And paragraph number seven of the Culbertson deeds says this:
“All mining operators shall in all future developments make reasonable provision for the disposal of tailings, dumpage and other deleterious material or substance in such a way as to prevent obstruction, pollution, or deterioration of lakes, ponds, or springs.”
These references to mine tailings, tunnels, shafts, and surface support, coupled with the prohibition against using more of the surface than is reasonably necessary, leave no room for doubt that the type of mining contemplated by the parties to the Culbertson deeds was deep mining.
As stated in Stewart v. Chernicky, 439 Pa. 43, 52, 266 A.2d 259, 264 (1970), a decision quoted with approval in Skivolocki, 38 Ohio St.2d at 249-50, 67 O.O.2d at 327-28, 313 N.E.2d at 377-78, “[t]he right to mine and remove coal by deeds conveying land in language peculiarly applicable to underground mining does not include the right to remove such coal by strip mining methods.” (Emphasis added by the Skivolocki court.) Just such language was used in the reservation of coal mining rights in the Culbertson deeds, and the rights so reserved did not include the right to remove coal by strip mining methods.
The express requirement in the Culbertson deeds that precautions be taken “for the support of the surface” is inconsistent with the notion that the parties intended to permit strip mining. A right of subjacent support of the surface is clearly pointless if the parties contemplate that the surface will be removed. “[Sjtrip mining,” as the Skivolocki court observed, “necessarily and unavoidably causes total disruption of the surface estate.” 38 Ohio St.2d at 248-49, 67 O.O.2d at 327, 313 N.E.2d at 377. And the fact that current regulations require the ultimate restoration of the surface does not diminish the force of this point.
It is true that uncontroverted evidence presented at the trial of this case indicates that in 1936, when the Culbertson deeds were executed, the area in which the Culbertson tract is located “was quite active in stripping for coal, clay and other mineral resources.” Strip mining, the testimony suggests, was by then a “commonly used” practice in this area.3 We do not find a single word in the Culbertson deeds, however, to suggest that the parties to the deeds had anything other than deep mining techniques in mind.
Of some significance, in this connection, is a compendium of Agriculture Department rules and regulations set out in the Culbertson deeds. The Department of Agriculture developed these regulations to govern the removal of minerals on lands acquired under the Weeks Act, and the regulations were required to be inserted in Weeks Act conveyances whenever mineral rights were reserved. The particular edition of the regulations incorporated in the Culbertson deeds, unlike later editions incorporated in the deeds to the Bauer, Simmering and Jenkins tracts, contained no reference to strip mining. The Culbertson deed regulations did refer specifically to underground mining, however. Like the main body of the Culbertson deeds, the attached regulations required that provision be made for support of the surface. To that end the regulations said *995that “the tunnels, shafts, and other workings shall at all reasonable times be open to inspection and examination.... ” The regulations also prohibited the pollution of lakes, ponds or springs by “tailings,” and called for special use permits for the construction of “structures such as mine shafts, tipples, derricks, pumphouses, hoppers, etc.....” It is hard to imagine language more peculiarly applicable to underground mining.
Belville invites us to consider extrinsic evidence in connection with the Culbertson tract, including evidence that strip mining was expressly prohibited in other deeds executed contemporaneously; evidence as to the extent of the mineral rights discount reflected in the purchase price for the Culbertson tract; and evidence of a 1956 Forest Service recommendation that a special use permit be issued for prospecting for coal, clay and limestone “in accordance with the reservation in the [Culbertson] deed.” (Clay can only be removed by surface techniques, and a 1957 Forest Service memorandum expressly mentioned “strip” mining as the purpose for which exploration was being conducted on the Culbertson tract.)
Under Ohio law, however, extrinsic evidence is admissible to illuminate the intent of the parties only where the terms of the deed are ambiguous. Cf. Wells v. American Electric Power Co., 48 Ohio App.3d 95, 97, 548 N.E.2d 995, 997 (Vinton 1988) (an issue of fact is presented, making extrinsic evidence admissible, where “the language is capable of two reasonable, but conflicting interpretations;” no such issue is presented if “the deed shows exactly what the parties intended”); Mead Corp. v. Jerome Goldberg & Cavalier Coal Corp., No. 78CA9, slip op. at 2, 1981 WL 5913 (Ct.App. for Gallia Co., Ohio, May 6, 1981) (parol evidence properly admitted to show intent as to strip mining where deed was ambiguous). Where the language of the deed is unambiguous, its proper interpretation is a question of law to be resolved by the court without resort to extrinsic evidence. Alexander v. Buckeye Pipeline Co., 53 Ohio St.2d 241, 246, 7 O.O.3d 403, 408, 374 N.E.2d 146, 150 (1978).4
We discern no ambiguity in the language of the Culbertson deeds sufficient to justify resort to the highly particularized extrinsic evidence proffered by Belville. If we are wrong in this, however, it does not seem to us that the evidence is sufficient to overcome the natural import of the deeds’ language, reading that language in the light of Skivolocki. The evidence as to contemporaneous deeds specifically prohibiting strip mining elsewhere does have some persuasive force, but it is hardly dispositive. The evidence on pricing is inconclusive. The evidence that the Forest Service interpreted the reservation of mineral rights as extending to clay — a mineral that can only be removed by strip mining — flies in the teeth of what the Culbertson deeds actually say. The only mineral rights reserved there relate to “coal, oil, [and] gas;” the deeds simply do not purport to reserve any right to extract clay.
The Bauer and Simmering Tracts
We shall consider the Bauer and Simmering tracts together, since the wording of the deeds and the relevant extrinsic evidence are similar with respect to both tracts.
The Bauer and Simmering deeds differ from the Culbertson deeds in several significant respects. Both the Bauer and Simmering deeds grant the right to remove “clays and shales of Ohio,” for one thing, and clays and shales of Ohio can only be removed through surface techniques. The use of “hydraulic” means is expressly prohibited in both deeds, but the use of other surface extraction techniques is not. Nowhere in the body of either deed do we find any language peculiarly applicable to underground mining, such as “tunnels,” or “shafts,” or “support of the surface.” And incorporated in both deeds is a 1937 edition of the Forest Service’s rules and regulations explicitly referring to the possibility of “stripping.” This edition (which also refers to “tailings,” inci-dently, but does not speak of “support of the surface,” or “tunnels,” or “mine shafts,” etc.) *996provides that if exercise of the mineral rights reserved in the deed will result in “stripping,” the owner of the mineral rights shall pay the amount necessary to restore the land to a serviceable or safe condition.
The government notes that the regulations themselves do not confer a right to strip mine, but it seems to us that given their context, the regulations — which are no less a part of the deeds than any other part— clearly contemplate the possibility that exercise of the reserved right to remove coal, clays, and so forth will be accomplished by surface mining techniques. If it had not been intended to permit the extraction of coal through surface techniques, for one thing, it would have been totally unnecessary to carve, out an exception for hydraulic means, the sole surface technique the use of which is prohibited. And by the early 1940s, when these particular deeds were executed, strip mining was well on its way to becoming the predominant method of extracting coal from the ground in Ohio.
The language of the Culbertson deeds was clearly focused on underground mining, as we have seen, with many of the deeds’ terms being peculiarly applicable to the use of deep mining techniques. The language of the Bauer and Simmering deeds was not focused on underground mining; that language included a specific reference to “stripping,” on the contrary, and it is at least as likely as not that the parties intended that stripping be permitted. Resort to particularized extrinsic evidence is entirely appropriate, then, as far as the Bauer and Simmering deeds are concerned.
The evidence offered with respect to the Bauer and Simmering tracts shows that in the 1950s the government placed a practical construction on the relevant deeds that is contrary to the construction for which the government now argues. Now the government says that strip mining rights were not reserved. In the 1950s, however, the reserved mineral owners of both the Bauer and Simmering properties were allowed to conduct surface mining operations under Forest Service permit. The Forest Service is a branch of the Department of Agriculture, and the representatives of the Service were doubtless in as good a position as anyone to know what the representatives of the Secretary of Agriculture had in mind when they purchased the Bauer and Simmering tracts in the 1940s. We find no error in the district court’s determination that strip mining was permitted under the Bauer and Simmering deeds.
The Jenkins Tract
In 1950, when the government acquired the Jenkins tract, strip mining was the predominant method of extracting coal in Ohio. The terms of the Jenkins deed were comparable to those of the Bauer and Simmering deeds, and, as noted above, strip mining operations were conducted on the Jenkins tract in the 1960s pursuant to Forest Service permit. If we are correct in our conclusion as to the Bauer and Simmering tracts, we have no doubt at all that a right to strip mine coal was reserved in the Jenkins deed.
There was a question, however, as to whether the reservation of the right to strip mine remained in effect on the Jenkins tract after 1989. The reservation was to expire at the end of that year, according to the deed, unless it should be shown by the grantors “that mining operations have been conducted to commercial advantage for an average of at least 100 days per year, during the preceding five year period.... ” The deed provides that in such event, subject to certain limitations, “the said right to mine shall be extended for a further period of five years.... ”
Belville cannot show, as far as we know, that mining operations were conducted in the manner stated during the five year period ending on December 31, 1989. The district court held, nonetheless, that “[sjince the Plaintiff sought and received from Defendant a determination prior to December 31, 1989 that it possessed ‘valid existing rights’ (VER), the reservation will be deemed to be in full force and effect at this time.” 763 F.Supp. at 1416. The government has not challenged this holding; without expressing any view as to whether the district court was correct, we affirm the holding on the ground that it has not been questioned here.
*997III5
1.
The district court concluded that, although Belville possessed VER in the Bauer, Jenkins, and Simmering tracts, Belville did not possess VER in the Culbertson tract. However, the court also found that OSM lacked either express or inherent authority to reconsider its initial determinations that Belville did possess VER in the four tracts. The district court reasoned, first, that nothing in SMCRA indicated, either explicitly or implicitly, that Congress had authorized OSM to reverse its “final” decisions. Second, the court found that, even assuming an inherent power to reconsider, Belville’s change of position in reliance on the 1988 determinations precluded reconsideration. Finally, in the district court’s view, although reconsideration for purposes of correcting clerical errors is within an agency’s inherent power, OSM’s reconsideration impermissibly was motivated by a change in policy. Therefore, concluded the court, OSM was without authority to reconsider and reverse any of its 1988 determinations.
Whether OSM had the authority, under the circumstances of this case, to reconsider and reverse its earlier VER determinations is unquestionably an issue of law. Therefore, we review de novo the district court’s conclusion on this issue. We hold that OSM had the authority to reconsider and reverse these determinations to the extent that they were erroneous.
In determining whether agency reconsideration is proper in a given case, “two opposing policies immediately demand recognition: the desirability of finality, on the one hand, and the public interest in reaching what, ultimately, appears to be the right result on the other.” Civil Aeronautics Bd., v. Delta Air Lines, Inc., 367 U.S. 316, 321, 81 S.Ct. 1611, 1616, 6 L.Ed.2d 869 (1961) (footnote omitted). The authority of an agency to reconsider an earlier determination may be expressly conferred by statute. Marshall v. Monroe & Sons, Inc. 615 F.2d 1156, 1158 (6th Cir.1980); Bookman v. United States, 197 Ct.Cl. 108, 453 F.2d 1263, 1265 (1972). Even where there is no express reconsideration authority for an agency, however, the general rule is that an agency has inherent authority to reconsider its decision, provided that reconsideration occurs within a reasonable time after the first decision. Dun & Bradstreet Corp. Found. v. United States Postal Serv., 946 F.2d 189, 193 (2d Cir.1991); Mazaleski v. Treusdell, 562 F.2d 701, 720 (D.C.Cir.1977); Bookman, 453 F.2d at 1265. The Secretary of the Interior has the inherent authority to reconsider an earlier agency decision. Ideal Basic Indus., Inc. v. Morton, 542 F.2d 1364, 1367-68 (9th Cir.1976).
The district court found that SMCRA neither specifically authorizes OSM to reconsider its VER determinations nor contains the sort of broad language that would constitute implicit statutory authorization for reconsideration. However, Section 201(c) of SMCRA, 30 U.S.C. § 1211(c), entitled “Duties of Secretary,” provides, in part, that
[t]he Secretary, acting through [OSM], shall—
(1) ... review and vacate or modify or approve orders and decisions....
* * its * *
We find that this statutory provision expressly authorized OSM to review and vacate the erroneous 1988 VER determination.
The applicable regulations also indicate that OSM has the authority to reconsider an earlier determination. Subpart A of Volume 43 of the Code of Federal Regulations, which is entitled “Public Lands: Interior,” sets forth general rules and regulations governing administrative appeals, including appeals to the Board of Land Appeals, which has juris*998diction over administrative appeals involving SMCRA. 43 C.F.R. § 4.1(b)(3) (1991). Section 4.5, entitled “Power of the Secretary and Director,” provides, in part:
(a) Secretary. Nothing in this part shall be construed to deprive the Secretary of any power conferred upon him by law. The authority reserved to the Secretary includes, but is not limited to:
5}s í¡{ í]{ «I»
(2) The authority to review any decision of any employee or employees of the Department, ... or to direct any such employee or employees to reconsider a decision, except a decision by the Board of Contract Appeals[,] which is subject to the Contract Disputes Act of 1978.
* * * * * *
These regulations thus expressly authorize the Secretary, acting through OSM, with one exception not relevant here, to reconsider “any decision” of “any employee or employees of the Department,” id., which would necessarily include a VER determination by an OSM employee.
Even if an agency lacks express statutory authority to reconsider an earlier decision, an agency possesses inherent authority to reconsider administrative decisions, subject to certain limitations. Rutherford v. United States, 806 F.2d 1455, 1460 (10th Cir.1986); Ideal Basic Indus., 542 F.2d at 1367; Bookman, 453 F.2d at 1265. However, the district court found that, even assuming OSM had inherent authority to reconsider, reconsideration was improper in the present case both because it was based on policy grounds and because it occurred after Belville had changed its position in reliance on the initial agency decision.6 As to the first of these reasons, the district court rejected the government’s explanation for reconsideration, namely, that the 1988 VER determinations had been procedurally and substantively deficient; instead, the court found that, because a Congressional investigation prompted reconsideration, and there was a contemporaneous change in directors at OSM, reconsideration impermissibly had been motivated by policy changes. We disagree and find that OSM properly exercised its inherent authority to reconsider and reverse its 1988 VER determination with respect to the Culbertson tract.
We recognize that a change in directors occurred at OSM during the relevant time period, and we also recognize that a Congressional investigation, at least in large measure, was the catalyst for reconsideration. However, we believe the record indicates that the underlying reason for reconsideration was a legitimate concern that the 1988 determinations had serious procedural and substantive deficiencies. This case is thus distinguishable from a situation in which an agency uses “the power to correct inadvertent ministerial errors ... as a guise for changing previous decisions because the wisdom of those decisions appears doubtful in the light of changing policies.” American Trucking Ass’ns, Inc. v. Frisco Transp. Co., 358 U.S. 133, 146, 79 S.Ct. 170, 177, 3 L.Ed.2d 172 (1958) (citing United States v. Seatrain Lines, Inc., 329 U.S. 424, 67 S.Ct. 435, 91 L.Ed. 396 (1947)). See also Upjohn Co. v. Pennsylvania R.R. Co., 381 F.2d 4, 5 (6th Cir.1967) (where “only basis” for reversal of previous decision is adoption of different policy, Interstate Commerce Commission lacked authority to “apply retroactively its new policy”).
Belville has presented no evidence, beyond the timing of the change in leadership, to suggest that the new Director of OSM, in initiating reconsideration in this instance, was attempting to change existing policy rather than.to correct erroneous VER determinations. The Investigative Report of the Subcommittee on Mining and Natural Resources, which criticized the Belville VER determinations, concluded that, because the administrative record concerning the 1988 determinations was so deficient, a court challenge would probably result in a finding that the decision was unlawfully arbitrary and capricious.
*999The inadequacy of OSM’s 1988 determinations is obvious: The determinations regarding these four tracts are contained in a con-clusory one-and-a-quarter-page letter consisting of nine sentences. The letter contains absolutely no legal analysis or factual explanation regarding the VER determinations. Furthermore, as found by a Congressional subcommittee, the determinations were based exclusively on the oral advice of a staff attorney and a single district court case from Ohio.7
The situation before us thus is not one in which OSM, based only on policy reasons, has decided to adopt one legally supportable position rather than another. Rather, it is clear that OSM here attempted to correct legally erroneous 1988 VER determinations that, left uncorrected, would be vulnerable to court challenge because of the wholly inadequate process by which these determinations were reached. Because the deficiencies in the 1988 VER determinations, rather than a change in policy, were the basis for reconsideration, the American Trucking Ass’ns and Upjohn cases are inapposite.
We also find that Belville’s reliance on the 1988 VER determinations does not preclude OSM reconsideration of this decision. The authorities cited by Belville and the district court are not to the contrary. In McAllister v. United States, 3 Cl.Ct. 394 (1983), the United States Claims Court considered the issue of whether a government agency may reconsider an earlier agency decision after the agency becomes aware that one of the parties has acted in reliance on the initial decision.8 The Claims Court in that case granted summary judgment for the plaintiff on the grounds that the initial decision was not erroneous, and the plaintiff had relied on this decision. In so doing, however, the court did not suggest that reliance on an agency’s decision inevitably would preclude reconsideration. The court instead adopted a narrower position:
“[BJarring a showing of error, an agency may reconsider its final decision only if the reconsideration is timely and the parties have not adversely changed their positions in reliance on that decision.... If the parties act on the initial decision, however, and if the agency knows they will act, then the agency may reverse its initial decision only upon a showing that it was erroneous."
Id. at 398 (emphasis added). We already have found that the initial VER determination with respect to the Culbertson tract was erroneous. Therefore, under the reasoning of McAllister, reliance on the erroneous VER determination is no bar to reconsideration, based on OSM’s inherent agency authority.9
*10002.
The district court also found that OSM’s reconsideration was untimely and, therefore, that OSM had waived the right to reconsider. Although this presents a closer question, we hold that, under the facts of this case, OSM’s reconsideration was timely.
The general rule regarding whether an agency reconsideration decision is timely is that, “absent contrary legislative intent or other affirmative evidence, this court will sustain the reconsidered decision of an agency, as long as the administrative action is conducted within a short and reasonable time period.” Bookman v. United States, 453 F.2d at 1265. See also Dawson v. Merit Sys. Protection Bd., 712 F.2d 264, 267 (7th Cir.1983); Alberta Gas Chem., Ltd. v. Celanese Corp., 650 F.2d 9,13 (2d Cir.1981). “What is a short and reasonable time period will vary with each case, but absent unusual circumstances, the time period would be measured in weeks, not years.” Gratehouse v. United States, 206 Ct.Cl. 288, 512 F.2d 1104, 1109 (1975). See also Mazaleski v. Treusdell, 562 F.2d at 719-20.10 Once this reasonable time period has run, “there is no longer an opportunity to correct the procedural error retroactively.” Gratehouse, 512 F.2d at 1109.
In reaching the conclusion that OSM reconsideration was untimely, the district court relied, in part, on OSM rules and regulations. See 43 C.F.R. §§ 4.1390-94 (1991). Section 4.1391 states, in part:
(a)The applicant or any person with an interest which is or may be adversely affected by a determination of [OSM] that a person holds or does not hold a valid existing right ... may file a request for review of that determination....
******
(b)(1) ... The request for review of a determination under section (a) ... shall be filed within 30 days....
******
(c) Failure to file a request for review within the time specified in paragraph (b) of this section shall constitute a waiver of the right to review and the request shall be dismissed.
The district court determined that, by not giving Belville notice of reconsideration until almost eight months after the initial determination, OSM failed to comply with the regulation’s 30-day appeal period in § 4.1391. Therefore, found the court, OSM had failed to act within “a presumptively ‘reasonable time.’ ” Belville Mining Co., 763 F.Supp. at 1422. The district court reasoned that, coupled with Belville’s reliance on the 1988 determinations, this failure barred reconsideration.
We find that Section 4.1391, by its plain terms, was not intended to apply to reconsideration decisions initiated by OSM. OSM is neither an applicant nor a “person with an interest which is or may be adversely affected” by a VER determination. Therefore, the 30-day notice and waiver provisions are inapplicable.11 In the absence of an ex*1001press time limitation within which OSM may, on its own initiative, reconsider an earlier decision, we must, therefore, determine whether, under the particular facts of this case, the eight months between notice of the 1988 determinations and notice of suspension and reconsideration of those determinations was a “short and reasonable period.”12
We initially note that neither party has identified unusual circumstances that take this ease outside the general rule. We also note that the eight-month time period involved here is intermediate between the weeks that, at least in the view of some courts, represent a presumptively reasonable period and the years that do not. See, e.g., Gratehouse, 512 F.2d at 1109.13
Recently, in the context of considering an appeal from a district court decision granting a motion to dismiss under Rule 12(b)(6), the Second Circuit enumerated three factors relevant to a determination of whether an agency reconsideration decision was timely: “We believe that a determination of whether the ‘time-lapse’ [81 weekdays] was reasonable will turn on, among other things, the complexity of the refund decision, whether the decision was factually or legally based, and whether the [agency] acted according to its general procedures for review.” Dun & Bradstreet Corp. Found., 946 F.2d at 194. Another court examined the following factors in concluding that an agency reconsideration decision was untimely: 1) the express time limit for appeals set forth in the regulations had run; 2) legally cognizable property interests had arisen through the initial decision; 3) the plaintiff had acted in reliance on the initial decision; and 4) the agency had attempted to use the pretext of fraud to justify reconsideration. Prieto v. United States, 655 F.Supp. 1187, 1192-93 (D.D.C.1987). To the factors enumerated by these courts we would add another factor we believe to be relevant here: the probable impact of an erroneous agency decision absent reconsideration. Cf. Civil Aeronautics Bd., 367 U.S. at 321, 81 S.Ct. at 1616 (desirability of finality must be weighed against public interest in reaching the correct result).
Weighing these factors, especially the complexity of the VER determinations, the absence of any showing of bad faith on the part of OSM, the fact that at the time OSM gave notice of suspension and reconsideration, Ohio had not issued permits allowing strip mining, and the likely impact of a decision to allow strip mining on national forest property *1002on which Belville does not possess VER, we conclude that reconsideration occurred within a reasonable time. We believe that the public interest in achieving a correct result here especially tips the scales in favor of a finding that reconsideration was timely. If the initial agency determination that Belville possesses VER in the Culbertson tract were found to be binding, even in the absence of VER, the probable result would be surface mining and the denuding of thousands of acres of national forest property that, pursuant to Congressional mandate, the Secretary of Agriculture has designated for inclusion in a national forest. SMCRA’s reclamation requirements notwithstanding, the fact remains, as found by the district court, that 100 years would elapse, following reclamation, before a new forest would replace the old one. Belville Mining, 763 F.Supp. at 1420.14
On balance, and taking all these factors into consideration, we believe that the eight-month time period between the 1988 determinations and the notice to Belville that these determinations were under reconsideration was reasonable. Therefore, we find that OSM reconsideration, and subsequent reversal, of its 1988 VER determinations was timely.
rv
We hold, first, that Belville had a valid existing right to strip mine on the Bauer, Jenkins and Simmering tracts, but not on the Culbertson tract. Second, we hold that OSM had the authority to reconsider and reverse its erroneous determination as to the existence of a valid existing right in the Culbertson tract, and we hold that Belville’s reliance on the erroneous determination did not bar reconsideration. Finally, we hold that reconsideration was timely. The judgment of the district court is REVERSED as to the Culbertson tract and AFFIRMED as to the remaining tracts.
. The terms "surface mining" and "strip mining” are used interchangeably to refer to the process by which coal is recovered by removing the overburden of trees, other vegetation, and soil, and scooping up the exposed coal by mechanical means. Current law requires restoration of the surface after the coal has been removed.
The term "deep mining” is used to refer to underground mining operations in which coal is extracted through tunnels and shafts. The residue produced in deep mining is known as "tail-ings.”
. Under Ohio's “syllabus rule” the actual holding is found in the Court's syllabus. The syllabus in Skivolocki reads as follows:
"1. Contracts are to be interpreted so as to carry out the intent of the parties, as that intent is evidenced by the contractual language.
"2. The right to strip mine for coal is not implicit in the ownership of a severed, mineral estate.
"3. A deed which severs a mineral estate from a surface estate, and which conveys the right to use the surface incident to mining coal, in language peculiarly applicable to deep mining techniques, does not grant the right to remove coal by strip mining methods.”
. Franklin v. Callicoat, 68 Ohio L.Abs. 67, 53 O.O. 240, 119 N.E.2d 688 (Lawrence Common Pleas Court 1954), says that strip mining was not practiced in Lawrence County (the site of the Culbertson tract) before 1943. Belville was not a party to that case, however, and was not precluded from showing that strip mining actually began in that area earlier.
. We realize that consideration of the mining techniques in common use at the time of the conveyance involves examination of matters ali-unde the deeds, but in practice the parol evidence rule has not precluded this kind of reference to the historic Weltanschauung.
. Except for a renumbering of footnotes and slight modifications to reflect the panel's views on the substantive validity of the final VER determinations, the part that follows is taken verbatim from a proposed opinion circulated by Judge Batchelder. Preparation of the court's opinion had been assigned to her initially, but her views on certain of the questions discussed above proved not to have the support of a majority of the panel. At Judge Batchelder's request, responsibility for writing a majority opinion was then reassigned. Judges Kennedy and Nelson concurred in Judge Batchelder's analysis of the government's right to change its mind with respect to the Culbertson tract, and we present that analysis here without material change.
. At oral argument, Belville stated that it had hired employees in preparation for mining operations and had entered into a contract to deliver a substantial quantity of coal that it anticipated would be mined on these four tracts.
. Sunday Creek Coal Co. v. Hodel, No. C-2-88-0416 (S.D.Ohio June 2, 1988). This earlier case is inapposite to the present case, because it involved a deed that "specifically reserved the right to remove the minerals by surface mining....” Id. at 1.
. In McAllister, the plaintiff, a civilian schoolteacher, worked for the Department of Defense Dependent School in England. Following reassignment to a new duty station, she requested and, on October 10, 1980, received from Jeffrey Dander, the individual in charge of Permanent Change of Station ("PCS”) determinations, a determination that she was eligible for PCS. As a result of this eligibility, she qualified for an extension of Living Quarters Allowance, in reliance on which she then incurred expenses that would have been reimbursable under this determination. However, on November 12, 1980, after she had incurred these expenses, plaintiff was notified by Dander's superior that, because the original determination was erroneous, PCS was being denied. The hearing examiner upheld this denial. Plaintiff brought an action in Claims Court and subsequently moved for summary judgment.
.The other cited reliance cases also are inappo-site. In Faircrest Site Opposition Comm. v. Levi, 418 F.Supp. 1099 (N.D.Ohio 1976), the court found that agency equivocation did not constitute arbitrary and capricious conduct. The court did not address the issue of whether reliance on an initial agency decision could be a factor in determining whether reconsideration was timely. In Confederated Tribes of the Warm Springs Reservation of Oregon v. United States, 111 Ct.Cl. 184, 1966 WL 8893 (1966), the court stated that it was "especially dangerous” for an agency to reconsider an earlier decision when there had been "reliance on the assumed finality of the decision.” Id. at 191, 1966 WL 8893. However, because "the initial determination had not passed beyond [the Commission’s] control” in that case, id. at 192, 1966 WL 8893 and thus there could be no presumption of finality, this language was dicta. Thus, neither of these cases supports Belville’s position.
Having found that OSM had the authority to reconsider its initial determinations, we need not address the argument that estoppel cannot be invoked against the government with respect to *1000the reconsideration determinations. We also need not address the argument that OSM lacked the authority to bind the government by an erroneous VER determination, because we have concluded that OSM had the authority to reconsider and reverse its earlier positive VER determination.
. Recently, the United States Claims Court has articulated a more liberal approach to the issue of whether agency reconsideration is timely. See Crager v. United States, 25 Cl.Ct. 400, 410-11 (1992) ("Although Assistant Secretary Bergquist’s de novo review was not really conducted within a short time, this court still believes that effective, unbiased de novo review of agency action should be promoted, regardless of the time which has lapsed."). In Crager, the Claims Court finding that an almost two-year period was not untimely appeared to have been motivated, in part, by a finding that the Assistant Secretary undertaking the reconsideration review was unbiased and by the fact that the reconsideration decision affirmed, rather than reversed, the earlier decision. Id. at 411.
. Nor do we believe, given the complexity of this VER determination and the inherent differences between a single adversely affected "person” and an agency, that application of this 30-day notice requirement to OSM is compelling as a matter of logic. See Ideal Basic Indus., 542 F.2d at 1367 (appeals regulation made applicable to "[a]ny party adversely affected ...” is not intended to preclude those who are responsible for managing public lands from "undertaking, or requesting, in a timely mannerf,] a reconsideration of a decision ... ”).
Belville cites to cases in which courts have applied specific time limitations to agency recon*1001sideration decisions. However, two of these cases involve regulations containing time limitations that, by their very terms, applied to the agencies as well as aggrieved parties. See Concerned Citizens of Bridesburg v. United States Envtl. Protection Agency, 836 F.2d 777, 786 (3d Cir.1987); Spanish Int'l Broadcasting Co. v. Federal Communications Comm'n, 385 F.2d 615, 621 (D.C.Cir.1967). In the third case, the court assumed, without deciding, that the ten-day appeal period for parties would also apply to agency-initiated reconsideration decisions. Confederated Tribes, 177 Ct.Cl. at 191-92.
. We deem this eight-month period between the initial determinations and the notice of suspension thereof to be the relevant time frame. As of August 24, 1989, Belville was on notice that the positive VER determinations had been suspended and were actively under reconsideration.
. See also Mazaleski, 562 F.2d at 720-21 (offer by agency to plaintiff to reopen administrative proceedings, which was made approximately one month after initial decision, when agency first learned of its error, was not untimely); Ideal Basic Indus., Inc. v. Morton, 542 F.2d at 1367 (Where reconsideration was requested within one month of original decision, even though reconsideration decision was not handed down until approximately 21 months later, "broad plenary powers” of the Secretary of the Interior "over the disposition of public lands” gave Secretary the authority to reconsider); Gratehouse, 512 F.2d at 1110 ("In the instant case, [the government’s] offer of a ... hearing 2 years after a hearing could have been held was far too late to qualify as reconsideration.”); Bookman, 453 F.2d at 1265-66 (reconsideration decision issued almost four months after rendering of initial decision was timely); C.J. Langenfelder & Son, Inc. v. United States, 169 Ct.Cl. 465, 341 F.2d 600, 604 (1965) (Where application for reconsideration was made more than a year after the original decision, this period was "much more than a reasonable period.' ”); Gabbs Exploration Co. v. Udall, 315 F.2d 37 (D.C.Cir.) (27 years between alleged administrative wrong and attempt to correct it held untimely), cert. denied, 375 U.S. 822, 84 S.Ct. 61, 11 L.Ed.2d 56 (1963); Crager, 25 Cl.Ct. at 411 (Although review almost two years after initial decision was “not really conducted within a short time,” reconsideration decision nonetheless was held timely.); Umpleby v. Udall, 285 F.Supp. 25, 30 (D.Colo.1968) (challenge to administrative decision made sixteen years after original decision held untimely).
. Because of the impact that the 1988 VER determination, if found binding, would have, the present case is distinguishable from those cases in which courts have found reconsideration decisions affecting a single individual to be untimely. See, e.g., Prieto, 655 F.Supp. at 1192 (denial of trust status of land belonging to plaintiff, an American Indian, who hoped to erect and lease billboards on land); Gratehouse, 512 F.2d at 1109-10 (denial of plaintiff’s request to withdraw his resignation from agency); Langenfelder, 341 F.2d at 604-05 (denial of additional payment to plaintiff for difficulties encountered in excavation work). Here, a finding that OSM is barred from reconsideration will have an impact extending far beyond a single individual.