Cyclothems

The recognition of more than 100 cyclothems in the Pennsylvanian and Lower Permian rock succession of Kansas, each containing a number of distinctive types of deposits and varied assemblages of organic remains, provides opportunity for paleoecological observations and interpretations which may come to be accepted as specially trustworthy. This ...

A stratigraphic unit having a number of cyclothems, may be studied over a large area in terms of the behavior of the entire section in response to tectonic or other controls, without minute examination of each member in each cyclothem. Thus, a scale factor to be discussed later is normally included in studies of cyclical deposits.These cyclothems have been well-studied and typically consist of a marine limestone, followed by a shallowing-upwards sequence of shales and sandstones, then an "underclay," and finally capped by a coal seam. Some Carboniferous sequences have dozens of such cyclothems so the creationist researcher must take them into consideration (Hampson ...In low latitudes, the deposition of the Carboniferous cyclothems was controlled by long- and short-eccentricity (Davydov et al., 2010). In high latitudes, orbital-scale climate cycles may also be preserved in the sedimentary succession. We aim to recognize whether or not orbital and millennial-scale climate cycles are preserved in the ...The black shale submember of core shales of Pennsylvanian Kansas-type cyclothems is highly enriched in redox-sensitive trace elements (TEs) relative to the overlying gray shale submember as well as to many other modern and ancient organic-rich deposits. Pennsylvanian glacioeustatic cyclothems exposed in Kansas and adjacent areas provide a unique opportunity to test models of the impact of relative sea level and climate on stratal architecture. A succession of eight of these high-frequency sequences, traced along dip for 500 km, reveal that modest climate shifts from relatively dry-seasonal to ...

The 20-30-m-thick cyclothems of the Sydney basin, Nova Scotia, Canada, show a systematic alternation of coals and other hydromorphic paleosols with calcretes and calcic vertisols. This implies strong variation in seasonality during the duration of a cyclothem, estimated at 200 ka. In at least one cyclothem, calcic paleosols formed on an ...Fossil of the month: Dunbarella This month's fossil of the month is Dunbarella.Is it a gold scallop fossil? Not really, but you might think it is. The fossil is an ancient ancestor of scallops, and the gold color is the mineral pyrite, sometimes referred to as "fool's gold."cyclothems in the midcontinent U.S. The cyclothems formed by cyclic sedimentation on epi-cratonic shelves during repetitive shoreline transgression and regression caused by large sea-level changes (Wanless and Shepard, 1936; Heckel, 1994; Yang, 2007). Sandstones in the Upper Pennsylvanian (Virgilian) OreadThere is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale rocks and their residual kerogens were determined by inductively coupled plasma-mass spectrometry. The results from this study show redox-sensitive elements relatively ...Vertical resolution of thick beds, thin beds, and thin‐bed cyclothems. Resolution has two common definitions. The first of these relates to determination of the position of a …Trace-element behavior and redox facies in core shales of Upper Pennsylvanian Kansas-type cyclothems. Chem. Geol. (2004) T.J. Algeo et al. Paleoceanographic applications of trace-metal concentration data. Chem. Geol. (2012) T.J. Algeo et al. Environmental analysis of paleoceanographic systems based on …

Carbonate units occur in varying numbers in the fine‐grade members of the alluvial fining‐upwards cyclothems present in the Lower Old Red Sandstone of the Anglo‐Welsh outcrop. They closely resemble contemporary soil‐carbonates (calcretes) and hence show that the local Siluro‐Devonian climate was relatively hot with a comparatively low ...The Anyue gas field in China is an important source of natural gas supporting the country energy transition to the goal of carbon-neutrality. However, the fluid P–T history, which will provide a better insight into gas accumulation and probable leakage in the main reservoir (the Lower Cambrian Longwangmiao Formation) has still yet to be fully …Cyclothems are separated by unconformity surfaces formed during predominantly degradational regressive and lowstand phases, which are represented by paleosols and equivalent incised paleovalleys, with the magnitude of sedimentary hiatus similarly increasing in duration in a northeasterly direction (Falcon-Lang et al., 2011a).Disconformity-bounded packages of sedimentary rocks, called cycles, cyclites, cyclothems, allostratigraphic units, and most commonly sequences, remained in focus for many decades, generating an impressive development of concepts, terminology, and discussion on local vs. global controls of base or sea level fluctuations [1, 2, 12-24].

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Cyclothems comprise arrays of terrigenous clastic, organic, and chemical/biochemical lithologies that record accumulation mainly on slowly-subsiding platforms and ramps, under limited ...Study with Quizlet and memorize flashcards containing terms like Describe the general steps used by geologists and other scientists in their attempt to solve particular problems or explain natural phenomena., Discuss the principles that Steno, Lyell, and Smith formulated for the development of the geologic time scale., Explain the difference between a geochronologic term, sometimes called a ...A new genus of gigantop- Heckel, P.H., 2008. Pennsylvanian cyclothems in Midcontinent North terid from the Middle Permian of the United States and China and its America as far-field effects of waxing and waning of Gondwana ice relevance to the gigantopterid concept. Int. J. Plant Sci. 172, 107-119. sheets.The oscillations of areas between ocean, river deltas, swampy coastal area, and more dry land led to the creation of rocks called cyclothems. If a certain area of land was a swamp area where large amounts of plants grew, shale would be deposited from the plant matter.The 20-30-m-thick cyclothems of the Sydney basin, Nova Scotia, Canada, show a systematic alternation of coals and other hydromorphic paleosols with calcretes and calcic vertisols. This implies strong variation in seasonality during the duration of a cyclothem, estimated at 200 ka. In at least one cyclothem, calcic paleosols formed on an ...

…record reflects the continued Gondwanan glaciations, which produced the extensive coal cyclothems (repeated sequences of distinctive sedimentary rock layers) throughout the …Hundreds of cyclothems occur in the rock sequence of the Carboniferous. Only one cause can do that - a long series of ice ages raising and lowering the sea level. And sure enough, in the region that was at the south pole during that time, the rock record shows abundant evidence of glaciers.Study with Quizlet and memorize flashcards containing terms like Ultramafic rocks were common during the Hadean. A lithologic example of an extrusive ultramafic rock is a ________________, while an intrusive ultramafic rock is known as a _________________., During the Archean, the shield rocks were made mostly of:, True or False? The lithostratigraphic term "member" would typically include a ...The strata are components of cyclothems and the main producing units are regressive (upward-shallowing) limestones. High-energy deposits such as oolitic limestones or mud-dominated carbonate buildups are altered and leached by exposure of these carbonates to weathering late during the development of each cycle (Caldwell, 1985). Daniels (1985 ...Rodinia. First known supercontinent formed during the movement of continents during the Mesoproterozoic Era. Pannotia. Second pangea-like continent formed around 650 million years ago after Rodinia. Craton 193. Name applied to a stable nucleus of a continent, consisting of a Precambrian shield and a platform of buried ancient rocks.Upper Pennsylvanian cyclothems were produced by quasi-periodic global sea-level fluctuations resulting from waxing and waning of continental icesheets during the Gondwanan Ice Age (Crowell 1978; Veevers and Powell 1987; Heckel 1994). Kansas-type cyclothems (as opposed to coal-bearing cyclothems of the Illinois Basin) areIn geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists who worked in coal basins formed during the Carboniferous and earliest Permian periods. The cyclothems consist of repeated sequences, each typically several meters thick, of sandstone resting ...cyclothems and detrital-rich cyclothems in Texas, Illinois, and the Appalachians are attributable directly to the greater detrital influx in the latter areas, which could relate as much to ...

Cyclothems. Alternating stratigraphic sequences of marine and non-marine sediments, interbedded with coal seams. - related to rise and fall of sea level during Gondwanan glacial cycles - often contain commercial coal--are indicative of cyclic depositional regimes.

The Carboniferous (/ ˌ k ɑːr b ə ˈ n ɪ f ər ə s / KAR-bə-NIF-ər-əs) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 million years ago (), to the beginning of the Permian Period, 298.9 mya. The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō ("bear, …Two different conceptual models underlie the application of sequence stratigraphy by Exxon stratigraphers and later researchers. One, the global sea-level model (GSM), relates to presumed sea-level behaviour through time; the other, the sequence stratigraphic model (SSM), relates to the stratigraphic record produced during a single cycle of sea ...This chapter provides an overview of cycles, rhythms, and cyclothems; nomenclature of cycles; methodology; time series and harmonic analysis; scale; phase, and facies; and classification and description of rhythmic or cyclic sedimentation. Cyclic sedimentation refers to the repetition through a succession, of rock units, which are organized in ...The stratigraphic basis for this investigation is a 410 m thick succession of Late Pliocene age, which is well exposed in the Wanganui River valley at Parikino, where it dips at 5-8° south without being faulted (McIntyre, 1997) (Fig. 1 Fig. 2).This is part of a very long section that extends for about 90 km north-south along the Wanganui River, and exposes semicontinuously Late Miocene to ...The meaning of CYCLOTHEM is a stratigraphic unit consisting of a series of beds deposited during a single sedimentary cycle.Vertical resolution of thick beds, thin beds, and thin‐bed cyclothems. Resolution has two common definitions. The first of these relates to determination of the position of a reflector in time or space. Resolution by this definition is inversely related to pulse width or sharpness of the wavelet and, potentially, directly related to bandwidth ...The Wanganui basin, New Zealand, contains a 2-km-thick, almost complete, composite record since isotope stage 100 (ca. 2.5 Ma) in the form of 47 superposed cyclothems of shelf origin. Each cyclothem corresponds to an unconformity-bound stratigraphic sequence, and typically contains a transgressive systems tract, sometimes a mid-cycle shell bed ...

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The cliffs also illustrate cyclothems I and II (Tullig Cyclothem and Kilkee Cyclothem) of the five in the Central Clare Group. These cyclothems are repeated sequences of mudstone, siltstone and sandstone, formed by normal processes in the deltaic environment that created these rocks. They are normally separated by thin marine bands with ...Prepare a list and discuss each of the eustatic and tectonic conditions that might account for the cyclicity for which cyclothems are named. (Answer from course answer key appendix 2) A cyclothem is a vertical succession of sedimentary rock layers deposited in response to a RISE and FALL in SEA level. Rocks in the lower part of the succession ...Abstract. The concept of sedimentary environment encompasses the entire complex of physical, chemical, and biological materials and processes involved from the time sediments are formed to the time they are examined. Thus, in addition to depositional setting, the tectonic setting, climate, provenance, postdepositional (diagenetic) conditions ...Upper Pennsylvanian (Virgilian and Missourian) cyclothems in the Lawrence, Kansas area : for illustration and discussion of PSA concepts. Responsibility prepared and compiled by Lynn Watney [and others]. Imprint [Lawrence, Kan.] : [Kansas Geological Survey], [1991] Physical descriptionHere, based on the cyclostratigraphic analysis of a deep-marine succession of Naqing in South China, chronostratigraphic correlation was achieved between Paleo-Tethyan deep-marine carbonate cyclicity and U-Pb zircon age-calibrated cyclothems from the Pangaean paleotropics.May 1, 2022 · The component cyclothems vary in the internal architecture through the Palougou Cyclothem from mixed retrogradational–progradational (R–P; R/P > 1) cyclothems 2–4 in the early TST to retrogradation-dominated (R/P ≫1) cyclothems 5–7 in the late TST, progradation-dominated (R/P ≪1) Cyclothem 8 in the HST, and fluvial aggradation ... The oxygen content of the Earth's surface environment is thought to have increased in two broad steps: the Great Oxygenation Event (GOE) around the Archean–Proterozoic boundary and the Neoproterozoic Oxygenation Event (NOE), during which oxygen possibly accumulated to the levels required to support animal life and …Continental-scale correlations of a Middle Pennsylvanian fourth-order sequence have provided evidence for the relative importance of allocyclic controls on the formation of Pennsylvanian cyclothems. These correlations (and related studies) indicate that eustatic changes in sealevel were the primary control on accommodation space in most basins.Cyclothems. A cyclothem is a series of repeating sediments representing the transgression and regression of H2 O or the submergence and emergence of land. In coal-bearing strata, changes in depositional environment produced a cyclic repetition of beds. The cyclothem is defined as a series of beds deposited during a single sedimentary cycle. In low latitudes, the deposition of the Carboniferous cyclothems was controlled by long- and short-eccentricity (Davydov et al., 2010). In high latitudes, orbital-scale climate cycles may also be preserved in the sedimentary succession. We aim to recognize whether or not orbital and millennial-scale climate cycles are preserved in the ...Mar 23, 2023 · In geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists that worked in coal basins formed during the Carboniferous and earliest Permian periods. The cyclothems consist of repeated sequences, each ... ….

Earth Sciences questions and answers. E. Late Paleozoic strata along the Appalachians may consist of as many as 50 vertically stacked cyclothems. Cy- clothems record a comparable number of sea-level cycles with an estimated average duration of approxi- mately 100,000 to 400,000 years each. These strata were deposited when continent-continent ...Request PDF | The Younger Namurian Cyclothems around Spanish Point | The Carboniferous rocks of County Clare are arranged into a broad syncline, with the result that the coastal outcrops in the ...The lithofacies asymmetry of cyclothems in the Strawn limestone (thinner transgressive units overlain by thicker regres- sive facies) supports the interpretation of glacio-eustatic sea-Core shales of Upper Pennsylvanian Kansas-type cyclothems represent a promising system for paleoredox analysis: they record a wide range of redox conditions (from mildly dysoxic to strongly euxinic), exhibit a fairly monotonic stratigraphic trend toward increasing oxygenation upward, and were of sufficiently short duration (<10 5 y) that the ...Chapter 10 Sedimentary cycles 10.1 INTRODUCTION Cyclic or rhythmic sedimentation is one of the aspects of stratigraphy that has attracted many geologists' attention and has led to a considerable amount of controversy. Some geologists have attached a great deal of importance to the cyclic development of stratigraphic history at the risk of ...1966. A simple model of an alluvial plain environment includes six distinct elements--channel, crevasse channel, levee, crevasse distributary, abandoned channel, and floodplain. Study of the model suggests that natural alluvial plains will tend to develop an internal cyclicity, so that the absence of cyclothems, or certain types of cyclothems ...A promising candidate for expanding our result from the Joffre Member are the potentially precession-scale (33, 34) Calamina cyclothems reported in certain intervals of the slightly older Dales Gorge Member of the Brockman IF, Western Australia , from which a preliminary estimate of 8 ky to 12 ky has already been published by ref. 34.Abstract. The Jurassic ( ∼ 201-145 Myr ago) was long considered a warm 'greenhouse' period; more recently cool, even 'icehouse' episodes have been postulated. However, the mechanisms ...Richter-Bernburg (1955b) identified four evaporite cyclothems (Z1-Z4) and although subsequently younger cycles (Z5-Z7) have been recognized in the axial parts of the Anglo-Dutch and North German basins, in Poland they are regarded as the subdivisions of the upper PZ4 cycle (Wagner, 1994; Wagner & Peryt, 1997). In Poland, the PZ4 cycle is ...Carboniferous coal & natural gas - cyclothems. PETM. Tools of the trade: Earth Materials - Mineral identification. Evolution Part II: Paleontological applications. Sequence stratigraphy. Geologic structures. Geologic maps. Way-up structures. Virtual field experiences (VFEs): Fossil correlation. Glaciers, glaciated landscapes, and glacial ... Cyclothems, The Lofer Cyclothems of the Alpine Triassic by Alfred G. Fischer. Princeton University, Princeton, New Jersey. Abstract. The Late Triassic Dachstein Formation (Lofer facies) of the Northern Limestone Alps in the region of Salzburg is a lagoonal deposit containing about 200 cyclothems. Cyclothems in the mid-part of the formation show a basal ... , abstract = "More conodont work on type sections, type areas and cores of marine units in the Tradewater Formation in Illinois, Indiana, and western Kentucky has established a better framework for correlating marine cyclothems of all scales, many of which have received local names in each state., Other articles where glaciation is discussed: glacial landform: …are being produced today in glaciated areas, such as Greenland, Antarctica, and many of the world’s higher mountain ranges. In addition, large expansions of present-day glaciers have recurred during the course of Earth history. At the maximum of the last ice age, which ended about 20,000 to 15,000 years ago,…, The meaning of CYCLOTHEM is a stratigraphic unit consisting of a series of beds deposited during a single sedimentary cycle., The sandstone is normally a sheetlike deposit grading down through siltstone into the underlying shale, but is separated locally and abruptly from the shale by an erosional unconformity which has been used to divide the sequences into cyclothems (Weller, 1930). In such cases the sandstone occupies linear depressions cut into the underlying shale., Fingerprint Dive into the research topics of 'New insights on the stepwise collapse of the Carboniferous Coal Forests: Evidence from cyclothems and coniferopsid tree-stumps near the Desmoinesian-Missourian boundary in Peoria County, Illinois, USA'., Beerbower JR. Cyclothems and cyclic depositional mechanisms in Alluvial plain sedimentation. Kansas Geol Surv Bull. 1964;169(1):31-42. Google Scholar Carlson B, Piliouras A, Muto T, et al. Control of basin water depth on channel morphology and autogenic timescales in deltaic systems. J Sediment Res. 2018;88(9):1026-39., Paleoclimate. My research interests focus on several aspects of the Earth System has operated in the geologic past. The most recent work involves characterization of the Hothouse planetary state, which appears to have developed more than a dozen times through the Phanerozoic. Under the right conditions, Large Igneous Provinces trigger a ..., ... Cyclothems represent: transgressive and regressive sequences. The Ouachita Mobile Belt changed in terms of style of sedimentation from a passive margin to an ..., The Iola Limestone is the open-marine, carbonate portion of a Midcontinent cyclothem. It represents the transgressive and highstand systems tracts of a stratigraphic sequence.The sequence begins with a type 1 sequence boundary at the base of the Chanute Shale, which underlies the Iola. This surface can be recognized by the presence of a paleosol and as much as 15 m of incision. Part of the ..., Abstract and Figures. Cyclothems are stratigraphic sequences deposited during glacial-eustatic transgressive-regressive inundations of land. Major cyclothems are most complete on lower shelves and ..., In terms of quality, the Colchester runs about average to slightly better than average for Illinois coal. Cady (1915) reported, based on three samples from each of 11 mines, an average ash content of 8.0%, with none more than 10%, and a sulfur content averaging 2.9%, with all samples between 2.0 and 4.0%., In geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists who worked in coal basins formed during the Carboniferous and earliest Permian periods. The cyclothems consist of repeated sequences, each …, Cyclothems are stratigraphic sequences deposited during glacial-eustatic transgressive–regressive inundations of land. Major cyclothems are most complete on ..., Again, there are two competing theories for what controls fourth order cycles. Often called cyclothems, the relative short time period in which individual layers of rock are never more than 1 million years. Glaciers are capable of causing quick changes in sea level that can show up in the rock record. , These cyclothems are typically 10-30 m (33-98 ft) thick, with individual members commonly less than a meter (3.3 ft) thick. Local development of sandstone channels and lenses, and coals is common in the thicker shales (Heckel, 1978; Heckel et al., 1979)., Pennsylvanian Paradox Formation, San Juan River canyon, Utah (RR28) November 30, 2020, posted in Sedimentary Geology. full size version: RR28. reduced file size version (more functional for some computers): RR28r. Cyclic Pennsylvanian Paradox Formation, inner gorge of San Juan River Canyon, Bears Ears National Monument., Cyclothems Fossil wood Glacial cycles ABSTRACT The first phase in the stepwise collapse of the Carboniferous Coal Forests occurred near the Desmoinesian–Missourian boundary (early Kasimovian, ~307 Ma), and involved extirpation of Lycospora-pro-ducing lepidodendrids, and some other lycopsids, across most of tropical Euramerica., The 20-30-m-thick cyclothems of the Sydney basin, Nova Scotia, Canada, show a systematic alternation of coals and other hydromorphic paleosols with calcretes and calcic vertisols. This implies strong variation in seasonality during the duration of a cyclothem, estimated at 200 ka. In at least one cyclothem, calcic paleosols formed on an ..., Terms in this set (11) Black Shales. Exact origin of the shales is debated. • Formed in undisturbed anaerobic bottom waters in shallow seas. • High biologic activity in overlying oxygenated surface waters. • Organic matter rained down on the seafloor and depleted the. sediment-water interface of dissolved oxygen., Study with Quizlet and memorize flashcards containing terms like Ultramafic rocks were common during the Hadean. A lithologic example of an extrusive ultramafic rock is a ________________, while an intrusive ultramafic rock is known as a _________________., During the Archean, the shield rocks were made mostly of:, True or False? The lithostratigraphic term "member" would typically include a ..., The Anyue gas field in China is an important source of natural gas supporting the country energy transition to the goal of carbon-neutrality. However, the fluid P–T history, which will provide a better insight into gas accumulation and probable leakage in the main reservoir (the Lower Cambrian Longwangmiao Formation) has still yet to be fully …, Pennsylvanian cyclothems, deposited in paleoequatorial Euramerican basins during the late Paleozoic ice-house period, are a classic example of sedimentation controlled by glacio-eustasy, with sea-level fluctuations driven by the waxing and waning of Southern Hemisphere ice caps (Veevers and Powell, 1987)., There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Learn more: USGS Water Science School: Glaciers and Icecaps National Snow and Ice Data Center: Facts about Glaciers U.S. Global Change Research Program ..., These cyclothems were mapped from outcrop across the Eastern Shelf and into the Midland Basin. Seventeen maps and 23 cross-sections were constructed to show regional net-sandstone distribution within siliciclastic systems, to document sequential depositional history and paleogeography, to analyze depositional response to paleobathymetry and ..., The Paradox Basin cyclothems previously have been interpreted as Milankovitch style glacial-interglacial cycles from the Late Paleozoic Ice Age, but an unambiguous test for a glacioeustatic origin has not been conducted. A high resolution coupled chemical and physical stratigraphic analysis of two outcrop sections and three core segments ..., Signatures of redox-sensitive trace elements (RSTEs; e.g., V, Cr, U, and Mo) preserved in marine sediments provide unique clues to the nature and changes of ocean oxygenation and redox states. There have, however, been few studies of the RSTE geochemistry of marine sediments in the South China Sea (SCS). Here we present the results of a study of concentrations of major elements Al 2 O 3, TiO 2 ..., 1). The origin of these cyclothems almost invari-ably is attributed to pulsating active tectonic epi-sodes separated by relatively quiescent periods. Cyclic climatic change is precluded because the known duration of these cyclothems (2.4 to 15 m.y.; Table 1) is 6 to 650 times longer than orbital-related climatic cycles, which have peri-, A grade scale for size of regular-shaped pores, utilizing the average diameter of equant or tubular pores and the width of platy pores, has three main classes: micropores (< 1/16 mm), mesopores (1/16-4 mm), and megapores (4-256 mm). Megapores and mesopores are divided further into small and large subclasses. Abundance is noted by percent volume ..., As two essential controls on the formation of organic matter (OM)-enriched shales, both paleoproductivity and preservation models remain controversial for the Wufeng and Longmaxi shales in the Sichuan Basin, southwest China. This study provides geochemical parameters as proxies for the paleoproductivity characteristics (Ba, P/Al, and (Ni+Cu)/Al), bottom water redox status (U/Th, V/(V+Ni), V/Cr ..., Cyclothems form in a regular pattern over geologic time. The most common type of cyclothem consists of four layers: a basal sandstone layer, an overlying mudstone layer, a limestone layer, and a final sandstone layer. This is known as the Van Houten cyclothem. Other types of cyclothems may contain different types of rocks in different ..., Rodinia. First known supercontinent formed during the movement of continents during the Mesoproterozoic Era. Pannotia. Second pangea-like continent formed around 650 million years ago after Rodinia. Craton 193. Name applied to a stable nucleus of a continent, consisting of a Precambrian shield and a platform of buried ancient rocks., sedimentary facies, physical, chemical, and biological aspects of a sedimentary bed and the lateral change within sequences of beds of the same geologic age.Sedimentary rocks can be formed only where sediments are deposited long enough to become compacted and cemented into hard beds or strata.Sedimentation commonly occurs in areas where the sediment lies undisturbed for many years in ...