Ladder Creek meteorite, Greeley Co., Kansas, USA

Latitude & Longitude (WGS84):	38° 37' 0'' North , 101° 37' 59'' West
Latitude & Longitude (decimal):	38.61667,-101.63333
Non-native locality type:	Meteorite
Köppen climate type:	BSk : Cold semi-arid (steppe) climate

Ordinary chondrite (L6; S3; W3)
Find, 1937; 35 kg

Several fragments of the Ladder Creek meteorite were found on the Edgar Linn farm and in nearby regions. Recovery of both the Ladder Creek ( L6) and the similarly fragmented Horace (H5) chondrites in Greeley County in these years were largely due to sustained efforts by Harvey Nininger to spread information about meteorites to local schools and newspapers. Inspections reveal indistinct chondrules and chondrule fragments within a largely equilibrated, but weathered matrix. Compositionally, equilibrated olivine (Fa25) and low Ca-orthopyroxene (Fs20.8) are characteristic of the L-chondrite geochemical group. Mineralogically the meteorite consists primarily of dominant olivine with pyroxene along with minor plagioclase, troilite, and Fe-Ni metal. Accessory chromite, copper, ilmenite and other minor sulfides have been reported.

Reported 4.04 Ga K-Ar age, 2.59 Ga U,Th-He age, and a ~1.2 Ma cosmic ray exposure (CRE) age provides some initial chronological markers to constrain the actual timing of the mineralogical record and apparent collisional events. In particular, the unusually short CRE age has drawn some special attention. In addition, a C-14 terrestrial exposure age (TEA) of 1.25 ka indicates that the meteorite has also experienced an additional millennium or so of weathering on or near the earth's surface before its discovery.

Ladder Creek is an excellent example of what were once described as 'well distributed' meteorites when Museums sought to have samples of almost any size to 'complete' their collections. Masses in the 2-10 kg range were distributed to the Natural History Museum (London), The Center for Meteorite Studies (Tempe, Arizona), The United States National Museum (Washington), The American Museum of Natural History (New York), and the Field Museum of Natural History (Chicago) Museum with several smaller masses distributed elsewhere.

Synonyms — Two fragments of Ladder Creek were first reported as separate meteorites ['Greeley County' and 'Horace (no.1)']; As each meteorite (each separate fall, witnessed or unwitnessed) is given a unique name, these two labels are referred to as Ladder Creek 'synonyms'. A third seemingly separate meteorite ['Horace (no.2)'] created a more complicated affair. Some fragments of 'Horace (no.2)' are also fragments of Ladder Creek. However, other fragments of 'Horace (no.2)' are fragments of a separate (H5) meteorite which was then renamed simply the 'Horace' meteorite.

Mineral List

9 valid minerals.

References

External Links