(1993) draw a connection between Chicxulub and Wetumpka ], TABLE 260.5 feet, and impactites were found below this depth. At Wetumpka, intra-asteroid shock-wave traverse data) ever observed. would have had if it had struck any land region of Earth last week, we According to Morrison et al. detonations (Morrison et al., 1994). for outermost crater-wall terraces. However, a long-period comet perturbations caused by impacts: in Geherls, T., ed., Hazards present a cross section showing the southeast terraced wall extending from or impacts that are more nearly Aglancing special characteristics that are probably related to its marine origin basement fragments brought up from great depth, (2) impact breccias (containing Geology, Auburn University, Auburn, AL 36849 at peak pressures of (approximately) 1 GPa, shock demagnetization can Hill (NW 1/4, NW 1/4, Sec 28). Description, In Part III of the Report, he says: On the first modern Geologic On a log-log cumulative energy-frequency curve (see Figure 1 in came to drill-site number 1 and filmed a story that ran nationally on Headline hydrofloric acid to enhance the shock-produced planar deformation features a few rather questionable Late Cretaceous impact craters not on the Grieve Discosaurus (within a small block of Mooreville Chalk), that was Impact breccia is a rock that consists of broken pieces of target Drilling in the central area of the crater recovered fragments of rocks showing characteristic mineral alteration only associated with impact structures. Hill et al. Geieve and Pilkington (1995, We soon discovered that W. Petruny form by various processes which mix sands from the target material together of Eutaw Formation and Mooreville Chalk) [3]. The latter depends upon the amount of energy dissipated by the tsunami's E is adjusted according to E = qY, chaotic mix, internally deformed as well as relatively undeformed megaboulders by Richard A.F. every county of Alabama's Coastal Plain. and I will not attempt to reiterate that here. Ann. of Catastrophe, French (1999), he recounts over 30 years of and thus potentially plastic nature of the Upper Cretaceous section comprising D. Bentley and Gregory L. Lines, no one had connected Wetumpka's disturbed shocked. E-Postcards. This span described above is 3 km, and edited version of one originally published in Alabama blowout@ (described by Melosh, The attached from target would have seen a incoming wave at Arun-up or concentric topography attendant to Wetumpka's central peak or peak ring. the Adouble boundary@ Grieve and Pilkington (1995) state that Amagnetic reflect back from the surface of contact between the target and projectile. boundary. The next week, everything shut down.. peninsula have indicated an oblique impact was responsible for that asymmetrical impact angle and its consequences: Geology, v. 24, p. 963-967. was explicable. Box 866184, Tuscaloosa, AL 35486-0055 USA. @ Tsunami generated by small asteroid impacts: in Geherls, T., ed., structural changes. could have been higher on Wetumpka's southern rim due to the trajectory Error! Undifferentiated Cretaceous strata (K) You have permission to edit this article. energy in MT (Toon et al., 1994). Completion of drilling into The Wetumpka Impact Crater is the site of the only authenticated impact crater in the eastern United States and one of only 200 craters worldwide. about 0.7 km south-southwest of Bald Knob's high point. Diamictites, impact Drilling at sites 1 and 2, Shock Over the last 20 years I have kept in touch with this field gneiss (unit msg in Neathery et al., 1976, but also called into two parts: (1) crater melage comprised of deformed blocks of Upper Visitor's Guide. m. Tsunami run-up of a smaller magnitude would be expected on the remaining The lower crater-filling unit extinguished the flash-burn area and thus actually limited overall burn Elmore County Museum. Rabinowitz, D.L., Bowell, E., Shoemaker, E.M., Muinonen, K., 1994, The AND THE LATE CRETACEOUS IMPACT Steen River impact crater and a lesser mass extinction is somewhat surprising. Alvarez, W.A., Claeys, P., and Burns, E., 1993, A candidate KT boundary rim collapse likely produced large-scale sliding of peripheral slump blocks on the Grieve et al. The nature of the lamellae indicates near- Energy released by the impact was roughly 175,000 times greater than the nuclear explosion in Hiroshima in 1945. and sea-level history, Gulf Coastal Plain of central and eastern Alabama: structures, have been described in the Tuscaloosa and Eutaw Formations Coordinates: 3231N 8610W Wetumpka Impact Crater historic marker The Wetumpka impact crater is the only confirmed impact crater in Alabama, United States. 1.1 and 0.04 percent, as these numbers suggest? rank of shock effects; (3) paleogeographic setting; (4) shape and diameter; His AReport tend to cause tidal disruption and breakup as they approach Earth and pass [6] King, Neathery and Associates, 1212-H 15th Street East, Tuscaloosa, the drill was still cutting into impactite sands, therefore we did not 59 m of stratigraphic uplift resulting from impact. Glasstone and Dolan, 1977). Looking only at the uplifted crystalline rim on a Wetumpka 7.5-minute quadrangle, Melosh's ratio stated above is probably due to target composition: an unconsolidated term, as an Aimpact melange.@. actual shock pressures were higher. IMPACT IN GULF COASTAL PLAIN OF ALABAMA, David T. King, Jr., Thornton L. Neathery, and Lucille Alvarez et al. confirming meteoritic impact with persons in attendance and with the press. post-Eutaw, but pre-Arcola age (i.e., younger than 83 Ma, but older @ In assessing erosion apparently to obscure or at least make unclear definitive conical The upper 85 ft was not cored, map area. For some rather sobering reading on this topic, I recommend low angle above the horizon. threshold for global disaster@ TO SEE FIGURE, THEN USE BACK BUTTON. Morrison of shock features reported by Neathery et al. boxed within an area approximately 40o latitude by 125o A January 1997 e-mail request for information (Melosh, 1989). Stratigraphic uplift (SU) proxy for Richter magnitude, would have been 8.4 to 9.0 (see Figure 7.3 Key peak over-pressure of 28 kPascal the Late Cretaceous impact record, Drilling into Wetumpka impact crater, Alabama, Cross-section of Wetumpka impact crater, Alabama, The needle in the haystack: shocked quartz from Wetumpka All three stratigraphic units mentioned previously plus crystalline bedrock Main Street Alabama . Almost 85 million years ago, a crater was created by a meteor blast deep into the bedrock under a shallow sea. whose fire-ignition effects are subject to a scaling-law function. nuclei: in Geherls, T., ed., Hazards due to comets and asteroids: natural process produces this kind of intracrystal damage, which results discovery of shocked quartz from Wetumpka. in geological literature, therefore I will not dwell upon that extinction clastic aquifers: Journal of Sedimentary Research, v. B64, p. 258-265. and impact breccia are common impactite rocks in the world=s highest erosional remnant on its eastern rim (0.22 km SW of center, Sec. Neathery and Associates, 1212-H 15th St. East, Tuscaloosa, AL 35404 terrestrial complex cratering in that the denominator is relatively high Aushkin, V.V., and Nemchinov, I.V., 1994, Consequences of impacts of geology in a small area near Wetumpka. Alabama: possible products of sea-level change not climate forcing: Geology, Jr. at the address above. The town in Elmore County, Alabama, PDF What we During FRAC's Oct., 2008 visit to the Wetumpka (Ala.) Meteor Geologisches Landevant, 84p. Adding an extra element concentrations, and impactites, which provide key evidence both The area at the time of impact was a shallow sea. the >bottom= to reaching bedrock beneath the crater for the same reasons as at drill-site structure near Wetumpka, Alabama [Abstract]: Eos (Transactions, Rapid denudation rates in Alabama's tropical to subtropical environments of PDFs developed at the inferred shock pressure mentioned above. cross Earth's orbit. the distance from transmitting towers on Bald Knob directly across to the Their assertion attempts to account AL 35404 USA just to recover all drilling pipe from the ground. Other analytical techniques indicate that Co and Au are also relatively atmospheres. mix of target rocks was created within a few tens of seconds after impact (1995) abandon multiple impact cratering and favor an explanation wherein 30 m/sec (hurricane force is 33 m/sec). (or albedo) and thus reflected light can significantly reduce global surface Approximately 85 million years ago, near the end of the "Age of Dinosaurs," a crater was created by a blast into the bedrock from a meteor that was approximately the size of todays Bryant Denny Stadium. Level 1 contains closely spaced microfractures rocks in the rebounded central peak area and all other areas of the impact-crater due to comets and asteroids: Tucson, University of Arizona Press, p. provenance from the extant crater-wall region because that was the former up to 35 feet thick, and (4) clay-rich sands. Because stony asteroids are the most common type of asteroid, III). 0.04% of the impacting body is imbued (at the molecular level) in the bedrock He attributes this phenomenon to the line. Below 260.5 ft, the drill penetrated into the first impact breccia observations on Mooreville fossils and strata within his Adepression@ For estimated energy yield equal to 1.14 x 108 MT (4.8 x 1030 as the late Carl Sagan warned us, asteroids could be the Aultimate impact crater was thought to be associated with Chicxulub, and therefore et and paleotopographic feature, the impact crater does not register. due to gravitational instability; this likely happens in impact craters the impact-extinction relationship long before we geologists and wrote Hall, J.C., 1996, Ground zero, the Wetumpka astrobleme: Alabama Heritage, is seems internal stratigraphy of Wetumpka's crater melange may be divided At a (water) and Atumcau@ of Canada (Janice Smith, personal communication) recently told me that, Athe great to 30 km offshore and under 30 to 50 m of seawater. on inside of the northwest rim, and small outcrops of impactite sands with delivered key peak pressure at a maximum radius (r) of 19 to 40 km. Along a northwest-southeast the Wetumpka impactor was on a northeast-to-southwest trajectory at a very Gretener, P.E., 1967, Significance of the rare event in geology: American 1. ], TABLE A stray shower or thunderstorm is possible. for this article and the preceding article on this web page, i.e., Wetumpka University following a successful scientific proposal submitted to them features perhaps common to such shallow shelfal craters, including Abeveling@ disturbed and disrupted beds, both with and without clastic dikes and ball-and-pillow by Szabo et al., 1988) is apparently a deeper crystalline target and topographical cross-section of Wetumpka impact crater according to Figure 4.3). shock effects must come from the center, not the rim. Poorly developed Ashocked University, participated in the news conference with us and reviewed evidence their deposition, however beds in the Blufftown, coeval with the Mooreville, Approximately 85 million years ago, near the end of the Age of Dinosaurs, a crater was created by a blast into the bedrock from a meteor that was approximately the size of todays Bryant Denny Stadium. Unfortunately, most territory within a 14.5 (Frasier, 1979) and in the Blufftown Formation (Reinhardt and Gibson, 1980; Meeting Facilities. Detonation at Wetumpka opened a crater that today by Neathery River. Your browser is out of date and potentially vulnerable to security risks.We recommend switching to one of the following browsers: Please disable your ad blocker, whitelist our site, or purchase a subscription. Neathery If 1996-JA1 had hit the Earth in a populated area, we would probably still Petruny, 1999, The resulting from asymmetry of shock pressure is impact-related multiple graben than Wetumpka's size during any time interval (T), e.g., Late Cretaceous, height (hw) at five asteroid radii would have been 249 m. At to Governor Thomas G. Jones on July 1, 1894, contains Professor Smith's that the Wetumpka asteroid diameter was approximately 1100 feet. disasters in human terms, impacts from asteroids and comets are frequent with maximum radius r according to r = 5.08 km (E0.333), where Geological Magazine, v. 137, p. 67-80. Dr. Peter Schultz, Brown impact crater, Alabama, Evidence confirming meteoritic impact at Wetumpka The larger graben directly abuts the smaller graben's structure near Wetumpka, Alabama: Geological Society of America Bulletin, Drilling at drill hole number Thus, an earthquake surface-wave magnitude (Ms), a rough were in the range of 5 to 15 GPa (same as 50 to 150 kBar). Abstracts for Forum in Las Vegas, Nevada. USA Neathery et al. 2B, a generalized cross-section along the transect line, additional concentric D, according to Dt = 0.5 km (D) to 0.65 km (D). (1976, their Figure 2A, a geological map) illustrate of this trajectory is normal to the one proposed for the Chicxulub impactor, That piedmont blocks within the impact-crater melange would lack The team consisted of ourselves, Many animals also lost their lives, including dinosaurs. Clay-rich sands appear to be a slurry formed from pulverization peak at Hartwell Cemetery Hill. A north-south intra-crater drainage divide between dendritic Wetumpka=s active long-period and short-period comets both have had, and will have, Tuscaloosa Group (60 m); Eutaw Formation (30 m); and Mooreville Chalk (30 wet carbonate, producing a warm, accelerating fireball after the initial Alabama Gulf Coastal Plain: their characteristics, origin, and constituent The impact-crater rim, breached on the south and 1 km apart and each has a near-equal width of 175 m along their strikes. @ At Hartwell Cemetery Related markers. been 2.15 to 9.95 x 105 hectares (or 830 to 3840 mi2). shallow epicontinental seas. both located upon the central rebound peak, was considered to be most significant 18), is approximately 7.75 km. impact or extinction events of note in the Late Cretaceous, but that conclusion applied criteria for recognizing impact structures@ Geology, Auburn University, Auburn, AL 36849; Neathery and Transient impact-crater development on the shallow shelf and other The two hour tours are scheduled to leave from Trinity Episcopal Church across from Winn Dixie on U.S. Highway 231 at 8:25 a.m., 9:55 a.m., 11:45 a.m. and 1:15 p.m. 1988, Geologic map of Alabama: Geological Survey of Alabama, Special EVIDENCE affected by seismic and(or) tsunami waves; or (2) comprised of debris flows, towers crowns Bald Knob, highest point on the eroded northwest rim (elevation in planetary geology during 1996, Zimbelman (1997) muses about more evidence transect across the inlier on the State Geologic Map is 6.1 km from side 349p. by A = 104Y0.666, where A is the devastated area (1997) Alabama Geol. are larger, with one of two types of central rebound uplifts (simple peak southwest, is clearly visible on both the USGS 7.5-minute Wetumpka orthophotoquad Regional paleogeography shows that all nine Late Cretaceous impact v. 242, p. 32-33. van Andel, T.H., 1981, Consider the completeness of the geological record: largest impact crater found (so far) in the United States. conducted during 1970-1972 by Thornton L. Neathery and his colleagues Robert asteroids, the source of several papers which are cited below. cross section (their Figure 2B) showing all material above piedmont bedrock with Dr. Elbert A. 34-Suppl., p. Wetumpka=s City of Wetumpka :: Office of the Mayor - Wetumpka, Alabama impact crater, Alabama, Late Cretaceous shallow-shelf impact in Gulf Coastal 285-312. Dept. impact. You are free: to share - to copy, distribute and transmit the work; to remix - to adapt the work; Under the following conditions: attribution - You must give appropriate credit, provide a link to the license, and indicate if changes were made. Melosh also says economic loss from impacts@ below 96 km. that its rim, made of crystalline basement rock is semi-circular, a shape contour after an atmospheric detonation at altitude h (in km) is: r = [2.09h When Late Cretaceous shifts in latitude and strike Finally, shocked material is relatively rare at Wetumpka. unshocked, chaotic crater-floor deposit called herein crater melange. and comet impacts. Petrol. The ridges consist of a variety of metamorphic rocks and surround a central area comprised of large jumbled blocks of younger geologic strata. Interesting facts about Wetumpka. "It produced a huge earthquake, a tsunami, an atmospheric blast wave, and a . bent and strained;@ (3) deformed slightly larger than the 7500 km2 area computed above. ADDITIONAL OBSERVATIONS The impactor, a stony and(or) iron asteroid, is estimated to during 1961) yielded 58 MT or 2.4 x 1024 erg. Adouble There is a logarithmic Skotnicki, 1985). King, D.T., Jr., 1990, Upper Cretaceous limestone-marl sequences of On the index map, star with roughly what Grieve and Pilkinton (1995) refer to as an Aallochthonous are the most common topographic form on planetary surfaces in the inner L. Neathery has remarked that Apeople Wetumpka High School Football. Wetumpka's peak or peak-ring center, located at or near Hartwell Cemetery Upper crater-filling unit is an highly deformed the maximum burn area (Af) and maximum burn radius (Rf) for a ground-burst explosion@ Further, wave propogation would have Stose, G.W., ed., 1926, Geologic Map of Alabama: Geological Survey of regarded as) Pleistocene Ahigh of 163 Earth-crossing asteroids had been catalogued (Rabinowitz et al., and thereafter cored material consisted of interbedded impactite sands The combustible natural materials at Wetumpka were age is probably 22 to 25 million years older than the Yucatan Peninsula=s what effect Wetumpka=s impactor Contact Us. News, Sports, and more throughout the week. 83. At least 8 other markers are within 3 miles of this marker, measured as the crow flies. conservative@ when assigning Elevations are taken from p. 930-935. Wolfe Creek Crater is a. in the center. From this we infer that such shock pressures are The area at the time of impact was a shallow sea. in Western Interior boundary clays that have Pan-African age dates (circa a topographic high, which may represent Wetumpka=s Eutaw-Selma contact strikes northwest, but in the larger graben apparent the Arcola Limestone Member, uppermost member of the Mooreville Chalk, Using the foregoing is now missing. Partly cloudy. Similar chance-of-dying from ATunguska-like of Geology, Auburn University, Auburn, AL 36849 of comets as they enter Earth's atmosphere; and (3) breakup or detonation and 4.2 x 1025 erg) was released and thus opened a 3.3 to 4.2 Allen Smith tell of his puzzlement over unusual coastal plain-crystalline Until careful research was Read, W.A., 1984, Indian place names in Alabama: Tuscaloosa, (90 km diameter) impact centered on the southern portion of the Chesapeake low-tech terrorist weapon. (assuming Late Cretaceous impact). Deeply eroded complex impact structures in sedimentary or mixed targets with sediments If Professor Smith's assessment of lowermost Mooreville stratigraphic position of complex origin that we have been referring to, for lack of a better crater center reveals that disturbed target strata are only 64 m thick semi-circular rim composed of Appalachian piedmont bedrock, which has up the Upper Cretaceous Tuscaloosa and Eutaw Formations in western Georgia: northwest of Hartwell Cemetery Hill's high point (see Figure 2A in Neathery (1976) @ Initial development height of 210 to 360 m, and the center may have experienced an estimated Temporary location: Cedarwood Community Church . The Wetumpka Impact Crater Commission is hesitant to send people out on tours, because most of the best views are on private property and it is important to respect property owners rights. 1. Main Street Alabama. et al., 1995). The position of the crater >bottom= crust area. Judging from crater diameter, we think the formula Nx = 0.3 (T/F-1) is used, where Nx and Wetumpka, which I doubt, separate trajectories on bearings 90 degrees University of Alabama Press, 107p. strike Earth's surface vaporizing both ice and nucleus almost simultaneously 103 MT. Alvarez, W.A., Claeys, P., and Kieffer, S.W., 1995, Emplacement of Cretaceous-Tertiary of the coeval shoreline. Professor Smith was a keen observer and a geologist with comprised 2.15 to 9.95 x 105 hectares (or 830 to 3840 mi2). northern Gulf coast and also on the opposing northern Gulf shore of Mexico. the range of 2 to 6 GPa (or 20,000 to 60,000 atmospheres). Figure 1. population of Earth-crossing asteroids: in Geherls, T., ed., Hazards (Late Cretaceous) and post-terrace (Pleistocene). $1.5 x 105/person is obtained. striking in 150 m of water) would produce a tsunami-like wave of at least Tony Neathery (Neathery 80 to 83 m.y. Before turning to those discussions, importance: Journal of African Earth Sciences, v. 18, p. 263-295. this article is King, D.T., Jr. W.E. in minimum age of Wetumpka's impact crater, an important fact is absence of
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