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19-652: The Palm Park Formation is a geologic formation in southern New Mexico . It preserves fossils dating back to the Eocene epoch . The formation consists of reddish clastic sediments , including some beds of boulder conglomerate with individual boulders up to 12 feet (3.7 m) in diameter. The red color is attributed to a source in the Abo Formation . The upper beds contains considerable latite to andesite breccia interbedded with tuffaceous claystone and siltstone . The Palm Park Formation rests gradationally on

38-446: A facies , stratum , bed , seam , lode etc. Thickness is measured at right angles to the surface of the seam or bed and thus independently of its spatial orientation. The concept of thickness came originally from mining language, where it was used mainly to indicate the workability of seams. It has since become an established term in earth science , for example in geology, for the depth of sedimentary rocks , in hydrogeology for

57-594: A geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Werner in his theory of the origin of the Earth, which was developed over the period from 1774 to his death in 1817. The concept became increasingly formalized over time and is now codified in such works as the North American Stratigraphic Code and its counterparts in other regions. Geologic maps showing where various formations are exposed at

76-526: A newly designated formation could not be named the Kaibab Formation, since the Kaibab Limestone is already established as a formation name. The first use of a name has precedence over all others, as does the first name applied to a particular formation. As with other stratigraphic units, the formal designation of a formation includes a stratotype which is usually a type section . A type section

95-594: A permanent natural or artificial feature of the geographic area in which they were first described. The name consists of the geographic name plus either "Formation" or a descriptive name. Examples include the Morrison Formation , named for the town of Morrison, Colorado , and the Kaibab Limestone , named after the Kaibab Plateau of Arizona. The names must not duplicate previous formation names, so, for example,

114-449: Is not a valid lithological basis for defining a formation. The contrast in lithology between formations required to justify their establishment varies with the complexity of the geology of a region. Formations must be able to be delineated at the scale of geologic mapping normally practiced in the region; the thickness of formations may range from less than a meter to several thousand meters. Geologic formations are typically named after

133-430: Is also used informally to describe the odd shapes (forms) that rocks acquire through erosional or depositional processes. Such a formation is abandoned when it is no longer affected by the geologic agent that produced it. Some well-known cave formations include stalactites and stalagmites . Thickness (geology) Thickness in geology and mining refers to the distance across a packet of rock , whether it be

152-560: Is central to the geologic discipline of stratigraphy , and the formation is the fundamental unit of stratigraphy. Formations may be combined into groups of strata or divided into members . Members differ from formations in that they need not be mappable at the same scale as formations, though they must be lithologically distinctive where present. The definition and recognition of formations allow geologists to correlate geologic strata across wide distances between outcrops and exposures of rock strata . Formations were at first described as

171-455: Is ideally a good exposure of the formation that shows its entire thickness. If the formation is nowhere entirely exposed, or if it shows considerably lateral variation, additional reference sections may be defined. Long-established formations dating to before the modern codification of stratigraphy, or which lack tabular form (such as volcanic formations), may substitute a type locality for a type section as their stratotype. The geologist defining

190-513: The Farallon Plate began to sink into the deep mantle and hot mantle rock rose to take their place, triggering the Mid-Tertiary ignimbrite flare-up . The Palm Park Formation contains hot-water stromatolites . Stable oxygen isotope measurements show that the fine layers (laminae) making up the stromatolites were deposited seasonally, with the sparry (coarsely crystalline) layers deposited in

209-539: The Love Ranch Formation , is unconformably overlain by the Bell Top Formation , Rincon Valley Formation , or Santa Fe Group , and has a thickness of about 2,000 feet (610 m). The original age estimate, based on radiometric ages of intrusions and interbedded flows , ranged from 42 to 51 million years. More recent high-precision U-Pb dating gives an age of 45.0±0.7 Ma for an ash fall tuff in

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228-603: The 1998 market. The formation was first named by V.C. Kelley and Caswell Silver in 1952 for exposures in Palm Park, southeast of Caballo . Because no complete section exists, a type locality was designated instead of a type section . Steven M. Cather and his coinvestigators assigned the Palm Park Formation to the Spears Group in 1994. Formation (geology) A formation must be large enough that it can be mapped at

247-550: The essential geologic time markers, based on their relative ages and the law of superposition . The divisions of the geological time scale were described and put in chronological order by the geologists and stratigraphers of the 18th and 19th centuries. Geologic formations can be usefully defined for sedimentary rock layers, low-grade metamorphic rocks , and volcanic rocks . Intrusive igneous rocks and highly metamorphosed rocks are generally not considered to be formations, but are described instead as lithodemes . "Formation"

266-522: The formation is expected to describe the stratotype in sufficient detail that other geologists can unequivocally recognize the formation. Although formations should not be defined by any criteria other than primary lithology, it is often useful to define biostratigraphic units on paleontological criteria, chronostratigraphic units on the age of the rocks, and chemostratigraphic units on geochemical criteria, and these are included in stratigraphic codes. The concept of formally defined layers or strata

285-569: The lower part of the formation in the Robledo Mountains and an age of 39.6±0.5 Ma for an ash fall tuff in the upper part of the formation in the Sierra de las Uvas . The interbedded ash fall tuffs and volcaniclastic beds of the formation are interpreted as volcanic activity after the end of Laramide mountain building but before the opening of the Rio Grande Rift . At this time, the remnants of

304-512: The spring and summer, and the micritic (fine-grained) layers deposited in the fall and winter. This suggests that laminae in more ancient stromatolites are also seasonal in nature. The formation also contains Eocene fossil vertebrates of Chadronian age. These are found in deeply weathered volcaniclastic beds of the middle and upper part of the formation that are interbedded with plant- and gastropod -bearing travertines , and most are also badly weathered. However, they include shell fragments of

323-643: The surface are fundamental to such fields as structural geology , allowing geologists to infer the tectonic history of a region or predict likely locations for buried mineral resources. The boundaries of a formation are chosen to give it the greatest practical lithological consistency. Formations should not be defined by any criteria other than lithology. The lithology of a formation includes characteristics such as chemical and mineralogical composition, texture, color, primary depositional structures , fossils regarded as rock-forming particles, or other organic materials such as coal or kerogen . The taxonomy of fossils

342-432: The surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of

361-477: The tortoise Stylemys , jaw fragments of Hyaenodon horriblis , tooth fragments likely of Hyracodon , and a partial skeleton of a protoceratid . Barite - galena - manganese deposits are present in the Palm Park Formation in the Rincon basin. These had produced 10,520 tons of barite and 1529 tons of 27%-40% manganese ore by 1998. The formation also contains gypsum and travertine, but not in economic amounts for

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