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Topic: Pre-Nectarian

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lntxt.doc Nectarian craters are equivalent to those previously mapped by Wilhelms and McCauley (1971) as late pre-Imbrian and include relatively fresh-looking middle pre-Imbrian craters. Similarly, most ejecta from pre-Nectarian craters was destroyed, but ejecta from those emplaced during late pre-Nectarian time may have contributed to the present-day terra mantles. Nectarian craters are identified by morphologic comparison with craters superposed on the Nectaris ejecta blanket. astrogeology.usgs.gov /Projects/PlanetaryMapping/DIGGEOL/moon/1062/lntxt.doc   (6407 words)

lftxt.doc Interpretation: may be related to various Imbrian and/or Nectarian basins Np HIGHLY CRATERED LIGHT PLAINSÑInterpretation: may be related to Nectarian basins It RELATIVELY FRESH-APPEARING, IRREGULAR TERRAÑLow relief; low density of superposed craters. The decline in impact flux between the Nectarian and Imbrian Periods is clearly evident on the far side in the relative paucity of Imbrian and younger craters and by the reduction in diameter of the largest craters in the three youngest systems. Nectarian highly cratered light plains (unit Np) are scattered across the map area as fillers in a few basins and large craters. webgis.wr.usgs.gov /downloads/digeol/moon/1047/lftxt.doc   (7276 words)

Adler Planetarium / Learning Astronomy / The Moon / Lunar Geologic Time Nectarian objects were created from 3.9 billion to 3.8 billion years ago. The most prominent features of the Nectarian age are 13 large basins formed from super-massive impacts. Nectaris is one of the oldest crater basins on the Moon. www.adlerplanetarium.org /learn/moon/time.ssi   (566 words)

Mare Smythii - Wikipedia, the free encyclopedia The Smythii basin where the mare is located is of the Pre-Nectarian epoch, while the surrounding features are of the Nectarian system. Mare Smythii (latin for "Sea of William Henry Smyth") is a lunar mare located along the equator on the easternmost edge of the lunar near side. The mare material, which make up the floor of the mare, is a high alumious basalt, and consists of Upper Imbrian basalt covered by Eratosthenian basalt. www.wikipedia.org /wiki/Mare_Smythii   (152 words)

Pre-Nectarian - Wikipedia, the free encyclopedia The Pre-Nectarian Period of the lunar geologic timescale runs from 4550 million years ago (the time of the initial formation of the Moon) to 3920 million years ago, when the Nectaris Basin was formed by a large impact. Pre-Nectarian - Nectarian - Lower Imbrian - Upper Imbrian - Eratosthenian - Copernican en.wikipedia.org /wiki/Pre-Nectarian   (90 words)

Lunar Meteorite Ages Strongly Support Lunar Cataclysm File Illustration: Maps showing regions of the Moon that were resurfaced during Nectarian Period (brown) and Imbrian Period (blue), and outlines of larger basins. The mysterious tilt of the moon's orbit is probably a natural consequence of the moon's formation from a giant collision with early Earth, according to a new study by scientists at Southwest Research Institute (SwRI). www.spacedaily.com /news/lunar-00e.html   (840 words)

letxt.doc The Nectarian and pre-Nectarian age assigned to the extensive, nondistinctive mantled terra material (geologic map unit NpNt, concentrated in province tm) reflects its probable origin as a mixture of degraded ejecta of Nectarian and pre- Nectarian basins and craters. The Nectarian Period was initiated by a large impact west of the mapped area that created the Nectaris basin, blanketed the pre-Nectarian crater-and-basin terrain with lineated and probably nonlineated ejecta, and created clusters of secondary craters. Chains and clusters of pre-Nectarian age are radial to the Crisium basin and could be remnants of its secondary impact retinue, as could a chain at lat 15¡ S., long 65¡E. (Hodges, 1973a), here mapped as Nectarian. webgis.wr.usgs.gov /downloads/digeol/moon/948/letxt.doc   (5077 words)

NEEP602 Between 3.9 and 3.8 eons, 14 large impact basins of Nectarian and Lower Imbrium age (Wilhelms, 1987, chapters 9 and 10) formed in a crust strong enough to support significant mascons and mass deficiencies. Large impact basins of Nectarian and Imbrium age formed in a crust strong enough to support mascons and mass deficiencies. Although the selection of the Nectaris impact event as the beginning of this time unit evolved from the lunar mapping program of the 1960s and 1970s (Stuart-Alexander and Wilhelms, 1975), the usefulness of its selection is reinforced by the Nectaris Basin being the oldest of the mascon basins. silver.neep.wisc.edu /~neep602/LEC10/EVOL/evolution1.html   (3632 words)

ALS Lunar Observers Certificate List of Objects Crater Gassendi: a complex crater from the Nectarian Period, filled with an abundance of post-impact changes. Note both the shape of the rim (somewhat squarish), the smooth floor (ejecta from the Imbrium impact), and the linear 'cuts' in the walls (local destruction from the Imbrium ejecta). Its smooth floor and the north-south mottling are from the Imbrium impact's ejecta. www.lunar-reclamation.org /observation_list.htm   (2616 words)

nectarian The Nectarian Period of the lunar geologic timescale The lunar geologic timescale divides the history of... The Nectarian Period of the lunar geologic timescale runs from 3920 million years ago to 3850 million years ago. The Nectarian Period of the lunar geologic timescale runs from 3920 million years ago to 3850 million years ago... webhosting4u2.net /word/nectarian.htm   (310 words)

Irene Antonenko, Ph.D. Thesis: Chapter 4 The Mendel-Rydberg basin is a Nectarian aged basin that is approximately 630 km in diameter [Wilhelms, 1987]. This interpretation is consistent with the observation of several potentially multi-layered cryptomafic deposits during the course of this study, as well as the suggestion that interleaving of ejecta deposits between volcanic layers may be a common phenomenon. The crater Hevelius is identified as Nectarian in age, and thus <3.92 b.y. home.the-wire.com /~iant/Thesis/chapter4/chapt4.html   (18788 words)

printthread.php?Board=lunar&main=387203&type=post By 1985 Pre-Imbrian had been split into Nectarian and Pre-Nectarian. Procellarian seems to have been dropped by 1971 when it became apparent that the maria were flooded at different times. I hadn't heard about Copernican not appearing on the latest farside map - I don't have a copy. www.cloudynights.com /ubbthreads/printthread.php?Board=lunar&main=387203&type=post   (153 words)

luna The Nectarian Period began 3.9 billion years ago when the Nectaris basin was formed and soon followed by the Humboldtianum, Humorum, Crisium and Serenitatis basins. The Imbrian Period began 3.8 billion years ago when the Imbrium basin was formed followed by the Orientale basin, which in turn was followed by great lava flows that filled the Tranquillitatis, Fecunditatis and Crisium basins 3.5 billion years ago with layer upon layer of "runny" basaltic lava. homepage.fcgnetworks.net /rduch/luna.htm   (713 words)

Lunar geologic timescale - Wikipedia, the free encyclopedia In many lunar highland regions, planetologists cannot currently distinguish between Nectarian and Pre-Nectarian materials. These deposits are called Pre-Imbrian age materials, which encompasses both time periods. The lunar geologic timescale divides the history of Earth's Moon into six generally recognized geologic periods: en.wikipedia.org /wiki/Lunar_geologic_timescale   (76 words)

Isostasy of the Moon from high-resolution gravity and topography data: Implication for its thermal history The lithosphere was already thick enough to support craters with diameters up to 300 km in the Pre-Nectarian and Nectarian Periods. Lithospheric thicknesses of the early Moon were investigated by comparing the gravity anomalies of craters and impact basins of various dimensions. Degree of isostatic compensation of larger impact basins suggested lithospheric thickness of 20–60 km at that time, which depended more on localities rather than age differences. www.agu.org /pubs/crossref/2004/2004GL022059.shtml   (225 words)

IngentaConnect Magnetic fields of lunar multi-ring impact basins Central anomaly fields are absent for the oldest pre-Nectarian basins, increase to a peak in early Nectarian basins, and decrease to a low level for Imbrian basins. However, the central basin anomalies suggest that the fields peaked in early Nectarian times and were low in Imbrian times, while samples provide evidence for high fields in Nectarian and early Imbrian times. The radial extent of the anomalies may argue for the former possibility, but the latter or a combination of the two are also possible. api.ingentaconnect.com /content/arizona/maps/2003/00000038/00000004/art00007   (285 words)

The Grand Canyon and the Moon It is common to group the Pre-Nectarian and Nectarian systems into the Pre-Imbrian, as in Shoemaker's original paper. The duration of the Nectarian is relatively small. They are not intended to make the reader a professional, but they should provide a basis for understanding the fascinating endeavor of reading the history of the Moon by looking closely at its features. www.astro.lsa.umich.edu /users/cowley/GCandMoon.html   (6042 words)

Waco News Volume No. 15 Issue No. 6 - June 2003 The Nectarian Period was followed by the Imbrium Period, which is when the basins flooded. The basin was formed by a massive impact approximately 3.85 billion years ago, marking the close of the Nectarian Period. For the most part, anything older than Nectaris has been obliterated by the bombardment of the Nectarian Period. www.whatcomastronomy.org /newsletter/200306.html   (3269 words)

Palaeos Hadean: The Hadean Eon For example the Nectarian Era is defined by reference to the formation of the Nectaris Basin (southwestern Nearside). Consequently, the time sequence and stratigraphy of the Hadean are largely based on lunar events. The Hadean has no place in the ICS system followed in the rest of Palaeos. www.palaeos.com /Hadean/Hadean.htm   (1861 words)

Moon The next 300 million years, 4.2 to 3.9 billion years ago, known as the Nectarian Period, also involved bombardment and several basins were formed, including, chronologically, Tranquillity, Imbriam, Serenity, Crisium and Orientale. Of these, the largest is the Imbriam basin, 900 miles across, caused by the impact of an asteroid 60 miles in diameter. The Lunar Highlands contain the oldest rocks, or breccia, formed during the Cataclysmic Period, during which 300 million years heavy bombardment from rocks and meteorites took place. infoman16.tripod.com /Articles/moon.htm   (7581 words)

Mass flux in the ancient Earth-Moon system and benign implications for the origin of life on Earth The masses of the basin-forming projectiles during Nectarian and early Imbrian times, when the last 15 of the ∼45 identified impact basins formed, can be reasonably estimated as minima. These in sum provide a minimum of 2 × 10 www.agu.org /pubs/crossref/2002/2001JE001583.shtml   (537 words)

Lunar Prospector Electron Reflectometry Tutorial The Nectarian craters lying away from the strongly magnetized antipodal regions are demagnetized, while those in the strong antipode regions are. You see that all the youngest craters are clearly demagnetized, as we saw in our statistical results. socrates.berkeley.edu /~jazzman/tutorial.html   (2392 words)

The Earth's Moon Part II Nectarian (3.92 to 3.95 billion years ago) Named for the Nectaris Basin, a huge multiring basin on the nearside that sent ejecta almost to the opposite side of the Moon. Includes almost four times as many large craters and basins as the Imbrian system and may contain some volcanic deposits. Includes crater and basin deposits and many other units formed before the Nectaris basin impact. wapi.isu.edu /Geo_Pgt/Mod06_Moon_a_b/Mod6Part2.htm   (1581 words)

Planetary.html There is almost no evidence on Earth of the Hadean Eon but the Nectarian (3850-?4200 Ma) and Pre-Nectarian Systems (?4200-?4450 Ma) on the Moon cover this missing period of time in the terrestrial rock record. Thus the Hadean Eon begins around 4450 Ma ago and extends to between 3900-3650 Ma depending of the age assigned to the ``oldest rock''. The formation of the Moon is conventionally ascribed to a giant collision between an impacting body about 0.20 Earth mass with the Earth about 50-100 Ma after T wwwrsphysse.anu.edu.au /nuclear/99report/Planetary.html   (1183 words)

Lunar Cataclysm Page 1 Maps showing regions of the Moon that were resurfaced during Nectarian Period (brown) and This also seemed to imply a lunar cataclysm ~3.9 Ga, which completely destroyed or metamorphosed impact melts produced by older impact events. www.lpl.arizona.edu /SIC/impact_cratering/lunar_cataclysm   (1068 words)

Mid-Term Examples, answer 5 Older planetary surfaces have more craters than younger surfaces, and by seeing which craters and their ejecta overlap different terrains (including other craters), a relative chronology was established, with major divisions: Nectarian, pre-Nectarian, Imbrian, and Eratosthenian /Copernican. Questions about GEOL101 or the Earth and Planets course should be directed to the instructor, Ralph P. Harvey, who charges only a modest connection fee. geology.cwru.edu /~harvey/GEOL101/exams/mtanswer5.html   (124 words)

Artemis Project: Summary of Lunar Stratigraphic Units Pre-Nectarian - Formation of the lunar crust, very heavy impact cratering, including basin formation Nectarian - Multiple large ringed basin forming impacts Early Imbrian - Impacts forming Imbrian and Orientale basins, significant impact cratering www.asi.org /adb/m/04/04/stratigraphy_summary.html   (299 words)

Bibliographie des DLR (LIDO) Humboldtianum basin (61N 84E; 650 km in diamter, middle Nectarian in www.dlr.de /lido/NE-PE/1993/ANP9402757491993.html   (265 words)

Moon Society: Geologic Processes on the Moon Medium sized craters that have lost their continuous ejecta and their 'sharp' rim are from the next period, called the 'Nectarian Period.' This period extends from 3.85 to 3.92 billion years of age. Medium sized craters that appear as simple bowl shaped objects without any rim or ejecta are the most ancient of all. They come from the Imbrium Period, which is from 3.2 to 3.85 billion years of age. www.moonsociety.org /certificate/lunargeology.html   (4843 words)

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