Amanz Gressly’s role in founding modern stratigraphy

Timothy A. Cross* Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401 Peter W. Homewood Elf Exploration Production, 64018 Pau cedex, France

ABSTRACT rary stratigraphic thought include: (1) the files. He recognized the coincidence of particular stratigraphic process-response system con- fossil morphologies with particular facies, and This paper discusses Amanz Gressly’s serves mass; (2) sediment volumes are differ- distinguished “facies fossils” from those that had (1814–1865) fundamental contributions to entially partitioned into facies tracts within a time value and that were useful for biostratig- stratigraphy in three areas: facies concepts space-time continuum as a consequence of raphy (“index” or “zone” fossils). He discussed and applications, stratigraphic correlation, mass conservation; (3) cycles of facies tract the equivalency of vertical facies successions and paleogeographic reconstruction. To facil- movements laterally (uphill and downhill) through a series of strata and lateral facies transi- itate access to his discoveries, we present an across the Earth’s surface are directly linked tions along a bed, developing the same principle English translation of his 1838 paper on facies to vertical facies successions and are the basis that later became known as Walther’s Law of the and stratigraphic correlation. We discuss ex- for high-resolution correlation of strati- Correlation of Facies. He distinguished between cerpts from this translation, which demon- graphic cycles; (4) stratigraphic base level is the time value of strata and properties that reflect strate that many of the fundamental princi- the clock of geologic time and the reference their genesis, and introduced specific terms to re- ples of modern stratigraphy were understood frame for relating the energy of space forma- flect this distinction. He used this understanding and expressed by Gressly. We put this into the tion with the energy of sediment transfer; and to show how stratigraphic successions should be context of subsequent development and re- (5) facies differentiation is a byproduct of sed- correlated across different facies tracts. Gressly finement of current stratigraphic principles. iment volume partitioning. supplied the concepts that replaced the founder- Gressly explained the genesis of sedimen- ing paradigm of Wernerian Neptunism, and he tary facies by processes operating in deposi- INTRODUCTION established many tenets of modern stratigraphy. tional environments. He demonstrated regu- His insights were relevant as much to the fields of lar lateral facies transitions along beds, which While other geologists were attempting to paleontology, paleobiology, paleoecology, and he interpreted as mosaics of environments solve the structure of the Jura Mountains, Amanz evolution as they were to stratigraphy. along depositional profiles. He recognized the Gressly (1814–1865), a Swiss geologist, was One purpose of this paper is to increase coincidence of particular fossil morphologies intent on unraveling the paleogeography of the awareness of Gressly’s contributions to the foun- with particular sedimentological facies, and deformed strata. In doing so, Gressly discovered dations of stratigraphy. To this end, we present distinguished “facies fossils” from those that and stated many of the principles that are the an English translation of his 1838 paper on facies had time value and that were useful for bio- foundations of modern stratigraphy. Despite and stratigraphic correlation. We also summarize stratigraphy (“index” or “zone” fossils). He numerous obituaries, short historical discussions, his statements about and understanding of fun- discussed the equivalency of vertical facies and fuller biographies—principally in German damental stratigraphic principles, and place successions through a series of strata and lat- and Swiss literature and principally focused on them into the context of contemporary strati- eral facies transitions along a bed, developing the history of the region in which he lived and graphic thought. With a knowledge of the the same principle that later became known as worked—his fundamental contributions are not philosophies and methods Gressly imparted to Walther’s Law of the Correlation of Facies. well known to earth scientists. This paper focuses geologists of his time, we can identify the few He distinguished between the time value of on his contributions to stratigraphic science in subsequent additions to Gressly’s “Laws” that strata and properties that reflect their genesis, three areas: facies concepts and applications, completed the foundation of stratigraphic sci- and introduced specific terms to reflect this stratigraphic correlation, and paleogeographic ence. Thus, a second purpose of this paper is to distinction. He used this understanding to reconstruction. show that many of the fundamental stratigraphic show how stratigraphic successions should be Although Gressly is widely credited with principles were established early in the practice correlated across different facies tracts. the first modern use and definition of “facies” of stratigraphy. Gressly derived an internally consistent, (Dunbar and Rodgers, 1957; Teichert, 1958), his logical, and comprehensive definition of a new contributions to stratigraphic principles are much PROVIDING A NEW PARADIGM TO stratigraphic paradigm, which was the basis broader and deserve greater appreciation. He ex- REPLACE WERNER’S NEPTUNIST for further developments and refinements. plained the genesis of sedimentary facies by CONCEPT The five remaining principles of contempo- processes operating in depositional environ- ments, and demonstrated regular lateral facies Gressly established a novel methodology and transitions along beds that he interpreted as philosophical approach to stratigraphic analysis *E-mail: [email protected] mosaics of environments along depositional pro- that replaced Werner’s Neptunist concept. Al-

GSA Bulletin; December 1997; v. 109; no. 12; p. 1617–1630.

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though the Neptunist concept already had been lished the following year (Gressly, 1837). In this the changes in environments across a geomor- challenged and abandoned by some of his con- paper Gressly gave a short definition of sedi- phic landscape. Rocks of the same types occur at temporaries (for example, see commentaries in mentary facies and related the facies he had ob- multiple stratigraphic positions, reflecting the Conkin and Conkin, 1984), Gressly offered the served to depositional environments. The first repetition of environments through time. Gressly alternative concepts and methods that were to be- part of Gressly’s major work, “Observations made his observations and derived his insights come the foundation of modern stratigraphy. géologiques sur le Jura soleurois,” was published from study of fossiliferous, shallow shelf and Kuhn (1962) argued that new paradigms in sci- in 1838, apparently with considerable help in reefal limestones. It is possible that the diversity ence follow a period of discomfort with the exist- composition and editing from his friends, partic- of facies and the abundance of the fossil assem- ing paradigm because of mismatches between ularly Thurmann. blages allowed Gressly to observe and to under- observation and theory; Gressly did his studies At the Solothurn meeting, Gressly also met stand the stratigraphic, paleoecologic, and geo- during such a period of discomfort. Louis Agassiz, the internationally respected pale- morphic significance of subtle variations in facies Gressly’s insightful departure from the exist- ontologist and geologist. Agassiz recognized the and their relations to time. ing paradigm contained three fundamental, re- novelty and importance of Gressly’s insights and To emphasize the originality of Gressly’s lated concepts. First, he recognized that the sedi- command of lithostratigraphic and biostrati- approach and his break from accepted strati- mentologic and paleontologic attributes of rocks, graphic data, and he encouraged Gressly to graphic practices, Wegmann (1963) and Teichert “facies,” reflected the processes of deposition continue with his work. After publication of the (1958) compared Gressly’s concept of facies within specific geomorphic environments. Sec- first part of the “Observations,” Agassiz pro- with that of his contemporary, Constant Prévost. ond, he understood that facies occur indepen- moted Gressly’s work by circulating the paper Both Gressly and Prévost distinguished between dently of time, and that time and rocks must be widely. In evidence, during the session of the the origin and physical attributes of a rock versus treated with separate concepts and vocabularies. French Geological Society on November 20, its age. Prévost, a rationalist, reached this conclu- Third, he established that there are predictable 1837, Marquis de Roys (a good friend of Prévost) sion using logical deduction, whereas Gressly patterns of facies relationships. He documented reported on his work on terrains of the southwest followed an empirical path and observed the dif- that facies occur in regular patterns of lateral tran- Paris basin, ending with a comment that the ferences. In publications dating a few years after sitions along a bed, and that these lateral transi- facies of these terrains were determined by their Gressly’s paper, Prévost (1839, 1845) redefined tions are repeated in vertical successions. This aspect, but not by their age (de Roys, 1837). two existing terms, “terrain” (designating rocks work was accomplished during his early twenties After the Solothurn meeting Gressly did not of different types but of the same age) and “for- from observations made on discontinuous, vege- return to Strasbourg, but went to Porrentruy and mation” (comprising all sediments originating tated outcrops, and without the benefit of much stayed with Thurmann. From November 1836 to from the same depositional process or environ- formal geological training. January 1838, Gressly was in Neuchatel for lec- ment) to distinguish between the temporal and Important reviews of Gressly’s education, tures given by Agassiz. Subsequently, he was em- physical attributes of strata. By contrast, Gressly collaboration with his contemporaries, work in ployed by Agassiz for several years as an assis- proposed an entirely different term, “facies,” to the Jura, contributions to stratigraphic science, tant at the Museum of Neuchatel to collect and separate clearly and distinctly the physical and and other biographical information were given curate fossils. Gressly’s fossil collection, care- biological aspects of rocks from their age. by Teichert (1958), Wegmann (1963), Meyer fully collected within a few years and recorded Wegmann (1963) argued that the redefinition (1966), Schneer (1972), Nelson (1985), Stampfli within a stratigraphic context, numbered more of existing terms was not sufficient to convey to (1986), and Schaer (1994). Gressly was born in than 25,000 specimens. Between January 1838 their contemporaries this new understanding the village of Bärschwil (Canton de Solothurn) and September 1839, Gressly was mentally ill, about the distinction between temporal and phys- in the German-speaking area of Switzerland and there is an absence of correspondence from ical aspects of rocks. Instead, Wegmann con- near the outer, northwestern thrusts of the Jura that period. This illness delayed publication of cluded that Gressly’s introduction of a different Mountains. After pre-university schooling in the rest of Gressly’s “Observations” until 1840 term was essential to emphasize the difference in Solothurn, Luzern, and Fribourg, he spent sev- and 1841. That Gressly did not subsequently concept. Gressly did not just redefine the term eral months in Porrentruy (Canton Bern), publish on facies is attributed to his fragile health. “facies,” which was in use in several geological Switzerland, to improve his French. In Novem- The main part of his work, consisting of 75 sci- contexts by Steno (see Winter, 1930; Friedman, ber 1834, at the age of 20, he went to University entific manuscripts, 57 field notebooks, and myr- 1990) and others (Conkin and Conkin, 1984; of Strasbourg to study medicine. While there he iad personal notes, is stored at the Museum of Markevitch, 1960; Nelson, 1985; Teichert, 1958). attended lectures on geology given by Phillippe Solothurn (Stampfli, 1986). Rather, he introduced the means to express this Voltz, the chief engineer of the Strasbourg min- Wegmann (1963) casts Gressly as a revolu- new way of thinking about the separate temporal eral district. He became friends with Julius Thur- tionary in the context of “normal” versus “revo- and physical aspects of rocks. mann, a professor of mathematics and natural lutionary” science, using terms formalized by science at Porrentruy, who also was studying ge- T. S. Kuhn (1962). The prevailing geological RECOGNIZING DISORDER AND ology under Voltz in Strasbourg. Thurmann’s re- notions of the time were derived from Werner’s CONFRONTING THE PARADIGM THAT search was on the stratigraphy and structure of Neptunist concepts, in which formations were ROCK AND TIME ARE INSEPARABLE the Bernese Jura. He encouraged Gressly to ini- considered contemporaneous, globally distrib- AND EQUIVALENT tiate parallel and complementary studies in the uted, specific rock types. By contrast, from em- adjacent Soloturn Canton to the east. pirical observation Gressly recognized that a spe- At the time Gressly began a study of Jurassic In July 1836, after two years of field work in cific rock type (“facies”) reflects its origin in limestones in the French and Swiss Jura Moun- the Solothurn Jura, Gressly went with Thurmann terms of environment and conditions of accumu- tains, stratified rocks [Werner’s Secondary] in to Solothurn to present an oral paper at the an- lation, not in terms of its age. Rocks of the same Great Britain and Europe had been divided into nual meeting of the Swiss Natural History Soci- age change character (“facies”) over distance large-scale stratigraphic units termed “terrains” ety. The extended abstract of his paper was pub- (that is, along depositional profiles), reflecting and smaller scale units termed “formations.” Ter-

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rains were considered global in distribution and In the areas that I have studied, perhaps more so than one which is generally practiced. Instead of being anywhere else, extremely varied petrographical or satisfied with a certain number of vertical sections as of the same age, whatever their composition or paleontological variations interrupt at every step the type sections [“types descriptifs”], I followed each inferred origin. Formations were classified and universal uniformity that was ascribed until now to stratigraphic unit [beds and subdivisions of forma- recognized by general lithologic characteristics the different stratigraphic units in the different coun- tions] along its horizontal extent as far as possible in and fossil assemblages which were thought to tries. They [these variations]2 are even repetitive in order to study all its variations. (10/21–29) typify each unit throughout extensive regions. several stratigraphic units, and cause astonishment for the geologist who attempts to study the nature of Because formations occurred in stratigraphic our Jurassic ranges. (10/1–7) In these passages Gressly recounted his chang- succession like terrains, formations were consid- ing perceptions about the approaches and ered both time bounded and lithologically dis- Gressly explicitly cautioned against assigning philosophies required to study the stratigraphy of tinct. Recognition of a particular lithology was an age to strata on the basis of lithologic charac- the Jura. He intended to conduct stratigraphic re- sufficient to define the age of the strata being teristics. He warned that because lithologic char- search using the existing paradigm and methods, examined. This perception of time-lithology acteristics are sufficiently alike in stratigraphic but he discovered that they did not work and were equivalency maintained the Wernerian tradition, units of different ages, a geologist can mistake specifically contradicted by his observations. He which assumed lithologic identity and global the age of a unit if its age is judged by lithology. empirically evaluated those concepts and meth- constancy of paleoenvironmental conditions Similarly, he cautioned that because the same ods that required modification in order to honor from one time period to the next. vertical successions of lithologies are repeated in both the data and his understanding of the dis- Gressly initially intended to use the strati- multiple stratigraphic units, a geologist can con- tinction between time and facies. Within this evo- graphic units that his colleague and mentor sider several temporally distinct stratigraphic lution of changing perceptions and practical ap- Thurmann had defined in the Bernese Jura, and units as one. proaches to studying the Soleure Jura, Gressly to apply them to the Soleure Jura (see Wegmann, developed fundamental principles that guide our 1963). Thurmann had established stratigraphic Commonly, he [the geologist] will stop with surprise science today. in front of formations he thought he knew well for a divisions and correlations in the traditional man- long time. Led astray by too much faith in accepted ner, measuring a series of stratigraphic sections geological dogma, which often generalizes purely ESTABLISHING THE CONCEPT OF [type sections] and then correlating the strata local facts, he will perhaps be mistaken about char- FACIES between them. The correlations were based upon acters that until then he thought belonged only to a given stratigraphic unit and to a subdivision in par- lithologic equivalency. ticular; he even will be tempted to completely con- Teichert (1958) summarized Gressly’s use of fuse several stratigraphic units going so far as to the term “facies” and his derivation of the facies My intention was to apply to the country where I live doubt their [separate] existence. (10/8–14) concept, and translated relevant passages into the geological laws that Mr. Thurmann verified with so much talent and success on the stratigraphic units English. We extend this process because of the neighboring Bernese Jura … (10/21–23)1 Gressly demonstrated that the same rock Gressly’s purpose was not just to propose the types occurred at multiple stratigraphic positions term “facies” for descriptive rock attributes inde- However, comparisons of time-equivalent independent of formations and their boundaries, pendent of time connotation. Rather, Gressly rec- formations between Great Britain and Europe and discovered, when he followed beds laterally, ognized it was essential to distinguish a rock term and within Switzerland and France convinced a regular lateral succession of petrographical and (“facies”) from a time term (“terrain” or time- Gressly that formations were not lithologically paleontological attributes along them. From stratigraphic unit). Without having a language to uniform. Gressly identified regional differences these observations and considerations, Gressly express these two properties of strata, one cannot in lithology among coeval stratigraphic units of determined that he would have to establish a dif- differentiate between lateral variations in lithol- formation and smaller scales. He also observed ferent sort of regional classification of strati- ogy (“facies”) along one or more beds [time- lithologic variability along beds, as well as dif- graphic units, one that did not assume lithologic stratigraphic units], and vertical changes and rep- ferences in vertical lithologic successions at dif- constancy within formations. He realized this etitions in lithology through a succession of beds. ferent geographic positions within strata in the would require detailed mapping of the lithologi- To recapitulate the observations and logic that Jura. Because the lithologies were not uniform cal changes within beds of formations. The Gressly followed, we begin with his understand- within either formations or smaller stratigraphic detailed mapping would establish temporal ing of facies. As illustrated by the following ex- units, age equivalence could not be assigned on equivalency of strata within formations, spatial ample, Gressly discovered through detailed field the basis of lithologic equivalence. His implicit variations in lithology within time-equivalent work in the Jura that rock types (“facies”) and understanding was that bed boundaries represent units, and the basis for inferring the paleo- their fossil constituents change in regular order very high-resolution time surfaces; therefore, geomorphology of fine-scale time slices. This along beds and in vertical succession from one geographic changes of lithology along beds approach would establish the basis for strati- stratigraphic unit to another. meant that the depositional conditions or environ- graphic correlations. ments also changed along a depositional profile. The coral facies comprises several subfacies, which vary in the different stratigraphic units [stratigraphi- In summary, Gressly recognized considerable …but soon I was forced to successively modify these [Thurmann’s] laws according to the diverse re- cally] and regions [geographically] of our Jura, and lithologic variation within formations at both gions which make up the Soleure Jura, and the study which are useful to know in order to understand the regional and local scales. He concluded that of these diverse regions necessitated on my part a laws of distributions of paleontological associations. lithology could not be presumed an a priori proxy system of research [research method] different to the These subfacies are explained as transitions that link the major facies, and allow appreciation of the for time. slightest nuances in the living conditions of the 2Brackets are used in the translation either to give organic world now buried in the earth’s crust. Thus the French word translated, as in [“terrain”], or to clar- coquinas link petrographically the purely coral 1Number before the solidus refers to page number ify a translation in order that we not stray too far from facies to the purely muddy facies, passing through in Gressly (1838); numbers after the solidus refer to the literal French. Parentheses and italics in the transla- the ooliths and pisoliths, to the sandy and gravelly line numbers. tion are from Gressly. varieties [mixtures] of the muddy facies. Analogous

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passages from one paleontological assemblage to provide a chalky white stone rich in fossil frag- along single beds. We have given citations from another always accompany these petrographic tran- sitions. (15/27 to 16/6) ments already used by the Romans for architec- Gressly (15/27 to 16/6; 16/16–26) in which he tural ornaments and sculpture. Other uses of stone discussed transitional facies between end mem- from the Corallian terrain include limestone spe- bers, gradual decrease in skeletal size within a Using this observation, I have managed several cially suited for mortar, and limestone suited for bed away from the source of the skeletal debris, times to follow [along a bed] the increase of debris use as a flux in making window glass. Gressly ob- and the association of specific fossil assemblages size [of skeletal fragments] and preservation to find the original habitat. There, one finds the fossils in tained his knowledge about these multiple uses of with specific facies. place, with a prodigious profusion and so well con- Jura limestones as a youth. He lived with his fam- Gressly also observed that biological [fossil] served that one can study the most minute details of ily in the glass factory, which was owned by the variations occur in consort with the physical the organization and characteristic assemblage, the more prosperous side of the Gresslys and which attributes in both end-member and transitional behavior and habits, as we will see in the following descriptions of terrains. (16/16–26) employed his father. He was familiar with the dif- facies and regarded these variations as reflections ferent applications of limestones of varying char- of the physical environment and the characteris- acteristics obtained from the numerous small tics of habitats. He explained that if individuals of Gressly applied the term “facies” to signify quarries excavated into a conspicuous single flat- a species occur outside their usual facies, they are those observable physical, chemical, and bio- lying coral bed near his home town. He had only more rare and morphologically atypical than logical properties of rocks that collectively per- to relate the different physical and chemical prop- when found in their typical facies. He also recog- mit objective description, as well as distinctions erties important for industrial application to the nized that generalist species occupy or dominate among rocks of different types. Gressly explicitly distribution of particular paleontological and sed- transitional facies, but specialist species domi- discriminated between objectively observable imentary attributes of facies. nate in the typical (end member) facies settings. properties and any connotation of their age. It is apparent that he considered it necessary to make ESTABLISHING THE RELATIONSHIPS In the meantime, it is perhaps not out-of-place to such a clear distinction because he abandoned the BETWEEN DEPOSITIONAL briefly comment on my present way of understand- ing the correlations between the geognostic consti- historical Wernerian term “formation” after the ENVIRONMENTS AND FACIES tutions of stratigraphic units [the attributes allowing first two pages of his publication, and subse- DISTRIBUTIONS geological interpretation] and the fossil assemblages quently used “facies” for a descriptive rock term they contain. (12/29–31) and “terrain” for a time-stratigraphic unit that Having explained that facies are properties of contained variable rock types. rocks not specific to time, Gressly further recog- These two end member rock types, either pure or nized that facies are products of genetic mixed, constitute facies well defined by their petro- In this way, I have come to understand that within graphic characteristics, which vary according to processes that operated in the depositional envi- their littoral or pelagic depositional environments. the areal extent [“dimension horizontale”] of each ronments in which they accumulated. Just as lat- stratigraphic unit there are several well-defined vari- Their paleontological features are no less distinctive ables which show the same features in petrographic erally linked depositional environments change and always correspond even in the slightest detail to composition as well as in the paleontologic attri- over a geographic area, the facies that are incor- the geognostical [structure, bedding and stratifica- butes of their fossil content, and which are governed porated into the stratigraphic record change gra- tion] and petrographic features, as we will see in by specific and fairly constant laws. (10/30 to 11/3) what follows in treating each stratigraphic unit in de- dationally along beds that parallel original depo- tail. I will only show here the major facies which are sitional surfaces. He observed that, by walking constant throughout all our stratigraphic units as far Above all, there are two major facts which define along beds and following changes in the physical as I know their extent through my own observations, everywhere the sum of the variables which I call and biological [fossil] components of facies, one all the more so in that the more or less numerous lo- cal and transitional subfacies can easily be linked to facies or the aspects of a stratigraphic unit: one is can establish the details of a depositional profile. that within a stratigraphic unit the occurrence of a the major facies. (13/11–21) specific lithology necessarily also requires the occurrence of a specific paleontological association; I think that the petrographic or paleontological and the other is that a given paleontological associa- changes of a stratigraphic unit in the horizontal are If, by chance, certain genera and species which char- tion rigorously excludes those genera and species of caused by the changes in environment and other cir- acterize a specific facies are found in another facies, fossils which are frequent in other facies. (11/4–10) cumstances, which still so powerfully influence it is a general rule that specimens of these genera and today the different genera and species which inhabit species will be much rarer, less developed and less the ocean and the seas. At least, I often have been as- characteristic than in the facies or general assem- Gressly provides some clues about the origin of tonished to find in the distribution of our fossils the blage to which they normally belong. Similarly, wherever the geognostic characteristics of a facies his understanding that facies change along beds laws of living communities and in the corresponding assemblages of petrographic and geognostic charac- [indicators of inferred depositional processes or en- and that laterally adjacent facies are time equiva- teristics which correspond to the living communi- vironments] are best developed, the paleontological lent. In the monograph that follows the text we ties, the environmental conditions which rule in the assemblages also are the best expressed, the genera have translated, he described different uses of the submarine world. (12/4–12) and species are most numerous and individuals are most typical, best developed, and are commonly in a rock varieties that compose the Corallian terrain. perfect state of preservation. If the facies show inter- Architectural uses of the different rock varieties Gressly understood the connections among mediate characteristics with mixed geognostic fea- are dependent on the natural dimensions of quar- facies, their genetic relation to depositional envi- tures, the fossils also share less typical attributes. In ried rock produced by bedding, and on rock ronments, and consequent lateral facies transi- this case they are generally rare, poorly preserved, strength. He noted that, whereas quarries near the tions along paleodepositional profiles; he also poorly developed and belong to few genera and species; however, there are occasional well-formed massive coral bioherm provide large, equidimen- observed regular order in lateral and vertical suc- fossils which belong mostly to different species than sional blocks used for wall construction, quarries cessions of facies. When he followed the beds lat- those in the principal facies or which rarely occur in farther from the center, in the same bed, provide erally, he always found the same lateral succes- them. (11/11–26) thinner slabs of homogeneous limestones used for sion of petrographical and paleontological attri- posts, lintels, and sills. Quarries from the bioherm butes. Gressly understood that he was walking Gressly recognized that fossil morphologies center (brecciated beds of the Corallian terrain) along depositional (time) surfaces as he walked reflect the physical and chemical attributes of

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their habitat, and regarded the fossil composition and useful for determining the niches they occupy in ronments) in which they occur, regardless of age. an ocean long gone from the surface of the earth. as being as informative and important to environ- (15/20–26) mental interpretation as the physical facies attri- Facies having the same petrographic and geognos- butes. He described parallel changes in fossil tic attributes show extremely similar paleontological characteristics throughout the stratigraphic succes- morphology and physical facies for reef and con- ESTABLISHING THE CONCEPTS OF sion [“terrains”], and occur in similar sequence tiguous shelf habitats, and demonstrated interme- VERTICAL FACIES SUCCESSIONS AND through a variable number of superposed strati- diate or transitional forms of each. LAWS GOVERNING LATERAL AND graphic units. (21/6–9) VERTICAL DISTRIBUTIONS OF FACIES Breccias, coquina, oolites, pisolites, mostly coarse After stating his second law, Gressly devel- grained, constitute the coral facies and associated Having established the genetic relation be- oped at length its significance to paleontology deposits such as reworked sediment and immediate transitions to muddy facies. These rocks always tween facies and depositional environments, and and biostratigraphy. He noted that facies of simi- show the characteristics of littoral and shallow ma- having equated the lateral variability of facies lar lithologic and sedimentologic characteristics rine deposits and only contain fossil assemblages along beds of the same age with the mosaic of contain fossil assemblages, which are analogous which are characteristics of coral beds, mainly com- depositional environments along depositional in terms of gross morphology, but that the fossils posed of fixed massive or branching corals, which profiles, Gressly considered the dynamics of the are different in detailed anatomy. He attributed resists the shock of waves and which living genera and species such as the Agaricias, Astreas, Oculinas, geomorphic process-response system through this observation to the general control of the habi- Caryophyllas, etc., today build coral banks and reefs time and extended these relations into the four- tat on morphology, whereas anatomical details in tropical seas that are so dangerous to ships. These dimensions of stratigraphy. He established that change from one stratigraphic unit to another, re- corals always are accompanied by other organisms the regular patterns and trends of facies observed flecting time dependency. In summary, because common to coral reefs, which appear to flourish in high energy, agitated water, thus always giving a laterally along beds were replicated through a similar facies are deposited in similar environ- morphology that provides resistance to the waves, vertical succession of beds. Moreover, the verti- ments of different ages, and because the external the ones being firmly fixed to the substrate, the oth- cal succession of facies through a series of super- morphology of fossils is related to habitat, fossils ers having an extremely elastic structure which gives posed beds was repeated within larger scale in similar facies will look alike regardless of age. and bends in the force of the waves but recovers stratigraphic units. The regular vertical succes- However, subtle variations in morphology are re- instantaneously, and comes out victorious from the incessant combat. The external morphology of the sion of facies was accompanied by a regular suc- lated to age (now, evolution). organisms and the layout of their organs are no less cession of fossils. Gressly explained these simi- Gressly’s third and fourth laws and accompa- appropriate to the circumstances which govern their lar vertical and lateral arrangements of facies and nying discussions concern the lateral and vertical existence. Commonly all these properties are united the controls of their distribution in the form of distributions of facies. The third law expresses to reach the objective. (13/22 to 14/10) five laws. the nature of lateral transitions, whether abrupt or gradational, from one facies to another. The In other examples, he compared fossil mor- After having determined the major facies which fourth law expresses regular, unidirectional in- dominate our Jurassic terrains, it remains to take a phologies in different habitats and related the look at the laws which underlie and control their dis- creases or decreases in diversity of facies as one assemblage of species (communities) in these tribution both vertically and horizontally. (20/22–25) passes along a bed or through a succession of habitats to morphologic adaptation to the physi- beds. The third law is somewhat ambiguous as to cal and chemical conditions of the respective en- Gressly’s first law that facies change transi- whether it refers only to lateral facies transitions vironments. In the case of muddy habitats cited in tionally within coeval beds is as follows: along beds or to both lateral transitions and verti- the following, Gressly observed that genera and cal facies successions through beds. The accom- species of the faunal assemblages have thin, Each facies of a stratigraphic unit has its own dis- panying discussions imply that Gressly was smooth, less-ornate shells that are not resistant to tinctive petrographic and geognostic or paleonto- aware that both abrupt and gradual facies transi- logic attributes which do not represent the charac- transport. teristics of the entire stratigraphic unit, nor the tions occur vertically through a succession of attributes of the other facies forming the same geo- beds and laterally along a bed. He recognized the A general trait, which is constant for all paleonto- logical level [stratigraphic interval]. (20/28–32) difference between normal stratigraphic succes- logical assemblages of the muddy facies, is that the sions and geographic dislocation or offset of facies dominant genera and species have tests less apt to resist destructive effects of reworking. The shells, This understanding of lateral facies transitions tracts. We consider his following statement as among others, are normally very thin, very much within time-stratigraphic units given by the first support for this opinion. smoother, less ornate, less ornamented with different law is the basis for correlation and stratigraphic protuberances than in the preceding [coral] facies interpretation of lateral and temporal equivalency Moreover, in some cases, following a considerable where they have a very pronounced massive resis- of rock bodies, as expanded upon by his para- [thick and laterally extensive] pelagic deposit, tant character. However, there are sometimes genera littoral facies appear abruptly, almost without any and species with very thick shells but which have a graph following the first law. gradual transition. This phenomenon, although in- less robust structure and which easily delaminate frequent, once again begins at the Lower Oolite. It and disaggregate by abrasion. (18/4–13) This law will help correct the classifications of many coincides with the abrupt or gradual horizontal fa- stratigraphic units and their subdivisions by defining cies transitions of the stratigraphic units which I more precisely their position [stratigraphically and pointed out previously. (23/1–6) He developed and illustrated several niche- geographically], and will therefore avoid the serious specific morphologic adaptations of species to their mistakes in determining the geological level of lo- habitats, as illustrated by the following example. calities (correlation of stratigraphic intervals) which Gressly’s third law is as follows: are separated by large rock bodies with different One very important characteristic which is universal characteristics. (21/1–4) Sometimes lateral [“horizontal”] facies transitions to organisms within the coral facies is a very thick are abrupt, sometimes the transitions are gradual shell, always highly ornamented by ribs, striations, and one facies passes into another through interme- spines, nodes, and other ornamentation giving a Gressly’s second law is that fossils share mor- diate varieties whose transitional features are strange, very particular physionomy, very irregular phologic attributes related to the rock types (envi- poorly expressed, which together with the mixing of

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end-member facies, makes it difficult to separate [transitional between pelagic and littoral] or pelagic tract predominates with respect to the others, some- them. (22/9–13) deposits. In other cases this transition is more grad- times being more littoral, sometimes being more ual and much less perceptible. This happens particu- pelagic, going from the Portlandian to the lower larly between coral and muddy littoral facies which oolite through the Coralline Terrain and the two Gressly’s fourth law is as follows: are commonly interspersed, as if their characteristics stratigraphic units of the Oxfordian. (24/6–11) radiated from the centers or nuclei of rich organic Diversity of the facies increases in a vertical direc- growth out to the periphery which only shows bro- ken debris or a few undifferentiated or poorly devel- tion from base to top throughout the whole series ESTABLISHING THE FOUNDATION OF [stratigraphic succession through the Jurassic] and, oped fossils. (22/14–23) conversely, diminishes gradually in the opposite WALTHER’S LAW direction. (22/24–26) Moreover, in some cases, following a considerable Gressly’s statement that abrupt or gradual [thick and laterally extensive] pelagic deposit, lit- Gressly’s laws are distilled from discussions toral facies appear abruptly, almost without any facies transitions occur in the same order laterally and commentaries about facies and stratigraphic gradual transition. This phenomenon, although in- along beds and vertically through a series of beds relationships he had observed in the Jura. Some of frequent, once again begins at the Lower Oolite. It is a description of relations among depositional Gressly’s commentaries relevant to the third and coincides with the abrupt or gradual horizontal environments, their distribution along a deposi- fourth laws include the following ideas. He recog- facies transitions of the stratigraphic units which I tional profile, and stratigraphy resulting from pointed out previously. (23/1–6) nized facies substitutions and explained that coral progradation, which later became known as boundstones and lagoonal mudstones may substi- Walther’s Law of the Correlation of Facies. In an- tute for each other in vertical successions and lat- With his fifth law, Gressly applied the other other part of the paper, Gressly further developed eral transitions because they occupy similar water four laws to reconstruct paleogeographies the idea of the equivalency between the lateral depth ranges. He described facies offsets or strati- through time. For successive time intervals he distribution of facies along a bed (depositional graphic discontinuities between successive beds, distinguished three facies tracts (“zone” and profile) and the vertical succession of facies in contrast to normal regular vertical facies suc- “band”): littoral, pelagic, and subpelagic, and he through a series of beds. A less-literal but more cessions. These stratigraphic discontinuities are mapped these over a wide area from the Vosges easily understood translation than that given in created by major lateral shifts in facies at specific and Black Forest in the north (along the Rhine the Appendix reads as follows: stratigraphic positions. Gressly observed that north of Basel, Switzerland), through the abrupt or gradual facies transitions occur laterally Neuchatel Jura, to the Savoy subalpine area in The subtle variations in faunal assemblages (related along beds and vertically through a series of beds, the south. Gressly recognized that facies diver- to lateral facies transitions) play an analogous role within each small-scale time-stratigraphic unit (al- thus demonstrating the lateral and vertical equiv- sity increases regularly across this region from beit on a vastly different scale) to that played by fos- alency of facies relationships, which has become the pelagic facies tracts in the south, through the sils of genuine stratigraphic value (such as the knotty known as Walther’s Law. subpelagic, into the littoral facies tract in the ammonite, the arcuate Gryphea, the Baculites) ver- north, and he established that these facies tracts tically within the larger-scale lithostratigraphic units. The coral facies comprises several subfacies, which maintained approximately constant geographic (11/27–12/3) vary in the different stratigraphic units and regions positions and widths throughout the Jurassic. of our Jura, and which are useful to know in order to understand the laws of distributions of paleontolog- The fifth law is stated as “The diversity of facies Thus, not only did Gressly understand that the ical associations. These subfacies are explained as is more or less constant in different regions lateral succession of facies along a depositional transitions which link the major facies, and allow [facies tracts].” (23/7) profile was repeated vertically through a series appreciation of the slightest nuances in the living of beds, but he understood that fossils had two conditions of the organic world now buried in the One could draw a line starting from Randen… as far fundamental uses. First, some fossil groups re- earth’s crust. Thus coquinas link petrographically as Chatelu…, running parallel to the foot of the flect the environments in which they live, and are the purely coral facies to the purely muddy facies, Black Forest and the Vosges which would divide the passing through the ooliths and pisoliths, to the littoral facies and the pelagic facies almost exactly particularly useful in paleoenvironmental inter- sandy and gravelly varieties [mixtures] of the into two separate parallel Jurassic zones. The west- pretation. Second, other fossil groups occur in muddy facies. Analogous passages from one pale- ern… swath continues toward… where it loses part specific, limited stratigraphic intervals, and ontological assemblage to another always accom- of its characteristics and only constitutes a very thin, pany these petrographic transitions. It is always the therefore are particularly useful for biostrati- irregular boundary between the pelagic deposits and graphic correlation. most delicate forms which dominate in the transi- the large Jurassic bay… which is almost entirely tion zones. (15/27 to 16/7) filled by littoral deposits which gradually thin from Gressly’s observations about the vertical and the Swiss border to the foot of the Vosges, showing lateral relationships of facies were almost imme- What I have said about vertical succession of facies paleontological characteristics which are increas- diately adopted and exploited, culminating in is not without exception, and it is obviously natural ingly littoral in all the terrains. (23/14–30) Walther’s (1894) reexplanation of the relation- that this law should vary according to the petro- ships and his discussion about how that informa- graphic aspects and geognostics of rocks and strati- The other zone which is pelagic, begins in Argovia tion could be applied in stratigraphic correlation. graphic units. We should thus not be surprised to and forms a less broad swath comprising the ranges By contrast, as noted by Teichert (1958), find within a muddy rock, above or below a coralline of the Soleure and Bernese Jura which lie on the edge rock, fossils which live in mud. But these fossils of of the Swiss basin and the Tertiary valleys which run Gressly’s observations about the two uses of fos- the muddy facies will indicate no less than the corals in to it. This swath is broader in the Canton of sils were not incorporated into common practice. a shallow marine or littoral environment even Neuchatel and would seem to comprise the whole of Gressly’s contemporaries focused on the facies though these rocks are of a different type according the Vaud and Geneva Jura. (23/31 to 24/5) to their depositional process. (21/31 to 22/6) and paleoenvironmental applications of fossils, and a more precise development of biostrati- The subpelagic facies tract is intermediate between graphic applications did not occur until Oppel’s Abrupt facies transitions are particularly obvious be- the littoral and pelagic facies tracts, and forms a tran- work in the 1850s. tween coral dominated facies and pure muds, above sition zone more or less closely linking them. In the Gressly stressed the value and application of all when the coral beds are surrounded by subpelagic Canton of Schaffhouse and in Argovia this facies paleontology in both contexts for two reasons.

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First, he wrote that a purely physical and miner- separated the temporal and physical attributes of Conservation Laws Apply to Stratigraphy alogical approach toward the study of sedimen- rocks in such a clear way—and defined corre- tary rocks, in the absence of paleontological in- sponding terms to express this distinction—he The first additional concept to the current strati- formation, was a sterile science. Second, he felt established a novel approach to stratigraphic cor- graphic paradigm was contributed by Johannes that a balanced physical and biological approach relation that is valid to this day. Walther (1894). He expressed a fundamental re- added important and corroborating information, quirement of stratigraphy, that the stratigraphic which made interpretations more robust. After REFINING THE NEW PARADIGM process/response system must conserve mass. Oppel, until the end of the century, biostrati- Walther’s understanding of this concept is ex- graphic applications dominated stratigraphy. In Gressly established the following strati- plained in the simple observation that a succes- response, Walther (1894) had a reaction similar graphic concepts: (1) sedimentary facies record sion of strata at one place is equivalent in time to to that of Gressly; he lashed out against the im- the processes and conditions of the environment a stratigraphic surface of discontinuity at another balanced use of fossils only for biostratigraphic in which they accumulated, and are interpreted place. That is, if erosion is occurring in one zone applications, just as Gressly had rejected the im- by analogy with modern environments; (2) sev- along a geomorphic profile, sediment must be ac- balanced, solely mineralogical approach to the eral facies coexist at the same water depth and cumulating elsewhere. Through this expression, study of strata in his time. Walther insisted on ap- may therefore substitute for each other as sedi- he accounted for the existence of unconformities plying detailed information about the physical ment accumulates through time; (3) the mor- and condensed sections at certain geographic po- aspects of strata, expanding and emphasizing the phologies of fossil species reflect the physical sitions that formed at the time when sediments principles first enunciated by Gressly. and chemical conditions of their habitat, but nu- were accumulating at other geographic locations. ances in their morphologies reflect evolution; Walther stated (1894, p. 996): “It is clear indeed, CONSOLIDATING AN APPROACH TO (4) certain fossils are more useful for interpret- that no material can disappear from the earth, that STRATIGRAPHIC ANALYSIS ing the environment of deposition (“facies fos- the mass of earth material remains constant (if we sils”), whereas others are more useful for estab- disregard falling meteorites).” This mass-balance Gressly concluded the first part of his paper by lishing the age of a stratigraphic unit (“index” or requirement, although essential to stratigraphic presenting the advantages of his stratigraphic ap- “zone” fossils); (5) time-stratigraphic surfaces understanding, is not commonly stated explicitly proach in four points. are defined by beds which follow depositional or used implicitly today. 1. It simplifies the apparent complexity in profiles; (6) facies change transitionally in a Walther’s understanding of mass-conservation paleontology and provides a coherent link be- unidirectional trend along depositional profiles, requirements was enunciated even more clearly tween paleontological and physical and litholog- and this trend is repeated in vertical sequence and specifically by Barrell (1917, p. 794): “A dis- ical attributes by establishing a limited number of through a succession of beds (a working de- conformity marks a period of time which is rep- closely interrelated laws. scription of Walther’s Law); (7) stratigraphic resented in some other region by a deposit of for- 2. It explains the physical attributes of sedi- correlations based upon lithologic equivalency mation [rock] value.” It is revealing that from the mentary rocks, “making them useful to science are demonstrated to be invalid for the area he start stratigraphic process-response systems were by carrying them from the realm of sterile [purely studied (and by extrapolation, this applies to all considered in the same context as other physical descriptive] mineralogy to the realm of geology cases); (8) stratigraphic correlations must be and chemical systems and regarded as operating by showing their relationships with the progres- based upon the time equivalency of stratigraphic with the same basic laws. sive development of life as is manifest at the dif- units, even if their facies differ; (9) the deposi- ferent epochs of the history of our planet [evolu- tional profiles and regional facies trends within Sediment Volume Partitioning tion].” a limited stratigraphic interval define the re- 3. It is the basis for reconstructing successive gional paleogeography. Recognition of mass conservation in the strati- paleogeographies and depositional profiles After Gressly’s contributions had been ab- graphic process-response system led to the corol- through time. sorbed into common practice, the addition of a lary concept of sediment volume partitioning by 4. It is the basis for reconstructing the times of few new concepts was necessary to complete Barrell (1912). Walther recognized that there was deformation using unconformities overlain by the current stratigraphic paradigm initiated by severe time-space partitioning of sediment at littoral deposits. Gressly. These additional concepts were (1) the times when erosional unconformities and sur- It is surprising that Gressly omitted from this stratigraphic process-response system con- faces of sediment starvation formed. Barrell ex- list one of the most important advantages, the one serves mass (and by implication the conserva- tended this concept to include time-space varia- that resulted from his initial questioning of the tion laws apply to stratigraphy); (2) sediment tions in volumes of sediment accumulated in Neptunist paradigm that his work helped discard. volumes are differentially partitioned into facies different facies tracts, even when unconformities He developed a new method of stratigraphic cor- tracts within a space-time continuum as a con- or surfaces of sediment starvation were absent. relation, based not upon establishing the equiva- sequence of mass conservation; (3) cycles of fa- Barrell illustrated the concept of sediment vol- lency of rock type, but upon establishing equiva- cies tract movements laterally (uphill and down- ume partitioning with a delta example. He lency of rocks in a time frame. We add to the four hill) across the Earth’s surface are directly showed that facies tracts moved uphill and down- advantages of Gressly’s approach to stratigraphic linked to vertical facies successions, and are the hill, and that the widths and thicknesses of these analysis a fifth; it is the basis for understanding basis for high-resolution correlation of strati- facies tracts increased and decreased in regular four-dimensional time-stratigraphic relation- graphic cycles; (4) stratigraphic base level is the progressions. Barrell thought that these changes ships. Gressly understood that there are two basic clock of geologic time, and the reference frame occurred in response to sea-level variations and concepts in stratigraphy: the first is that sedi- for relating the energy of space formation with uphill and downhill movements of sites of sedi- ments accumulate by a set of processes in depo- the energy of sediment transfer; and (5) facies ment accommodation. This principle has been sitional environments, and the second is that this differentiation is a byproduct of sediment vol- applied in stratigraphic interpretation of seismic happens during the passage of time. Because he ume partitioning. data during the past two decades, largely due to

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the popularity of seismic and sequence stratigra- “The simplest consideration will teach that this tion of uphill (or landward) facies tracts, resulting phy initiated by Peter R. Vail’s group at Exxon task [stratigraphic correlation] cannot be ful- in a downhill-to-uphill (or deep-to-shallow) ver- (Payton, 1977). filled with the help of organic remains and on the tical succession of facies. Because environments basis of characteristic fossils.…Here paleontol- are laterally linked along a depositional profile, Cycles of Facies Tract Movements are ogy alone can do nothing and needs the help and the downhill and uphill translations of environ- Equivalent to Stratigraphic Cycles Defined support of other methods. We believe that com- ments are recorded simultaneously at all posi- by Vertical Successions of Facies parative lithology can remove these same diffi- tions along a depositional profile. Vertical facies culties which comparative anatomy has dis- successions at all positions within a stratigraphic Walther is better known today for his “Law of charged for the field of paleontology.” And he unit record these simultaneous translations of en- the Correlation of Facies” than he is for express- believed that (1894, p. 981) “there are no zone vironments and are the basis for stratigraphic cor- ing the requirement that mass is conserved in fossils that can tell us which rocks are to be seen relation. This explicit linkage between the “zig stratigraphic process-response systems. This is as heteropic, simultaneous deposits of the whole zag” uphill and downhill movement of environ- largely due to Middleton’s (1973) account of earth surface.…The geologist finds himself in ments and the expression of these movements in Walther’s work. Middleton focused on Walther’s the fatal situation of being unable to recognize vertical facies successions as stratigraphic cycles understanding of the relationships between verti- different formations either as contemporaneous is the insight Walther added to the lateral and ver- cal facies successions and lateral facies transi- or as belonging to different ages with cer- tical relationships that previously had been de- tions which are required geometrically by sedi- tainty.… only the ontological method can save scribed by Gressly and which are now called ment accumulation on an inclined surface, that is, us from [bio]stratigraphy, and only the laws of “Walther’s Law.” progradation. However, Middleton did not dwell the correlation of facies are in the position to on the importance of those relationships in the widen our knowledge.” Finally, he noted that Stratigraphic Base Level is a Reference context of stratigraphic correlation, even though even unconformities and other surfaces of strati- Frame for the Passage of Time and the Sites it was within this stratigraphic context that graphic discontinuity only help establish relative of Sediment Accumulation, Erosion, and Walther constructed his law, as was emphasized ages of rock units rather than true temporal Nondeposition by his title. To understand Walther’s insistence equivalency of correlation (1894, p. 983): “when about the need to formulate such a law for the a transgression results from a positive shoreline The initial step toward the next fundamental purpose of stratigraphic correlation, we view his shifting, the single discordance cannot possibly new stratigraphic concept was Barrell’s (1917) insight from a historical context. be of the same age, and the ‘relative same age’ is recognition that stratigraphic successions record Walther first restated Gressly’s observation encountered rather lamely again.” transits of base level up and down across the that the descriptive, physical attributes of a rock With these arguments Walther established the Earth’s surface. Where base level is above the (Gressly’s “facies”) reflect the processes that need for a method of temporal correlation of Earth’s surface, sediment will accumulate if sed- operated in the environment where the sedi- strata independent of biostratigraphy. In reaction iment is available. Where base level is below the ment accumulated. Walther wrote (1894, to what he considered an excessive emphasis of Earth’s surface, sediment is eroded and trans- p. 977), “When we examine the primary quali- using fossil data exclusively as the basis for ferred downhill to the next site where base level ties of the rocks, we cannot help but notice that establishing temporal relations of strata, Walther is above the Earth’s surface. These transits of in many ways they are strongly dependent on focused on physical attributes of strata for corre- base level up and down across the Earth’s surface external conditions.… But there is not only a lation. He even stated that the primary purpose of produce a stratigraphic record at a fixed geo- causal relationship between the single deposit his book was to describe a method of strati- graphic position of alternating episodes of depo- and the climatic conditions under which it graphic correlation based upon the concept of sition and erosion seen as regular vertical succes- arose, but also the several types of structures of equivalency between lateral facies transitions and sions of facies separated by surfaces of one and the same facies tract are most closely vertical facies successions (Walther, 1894, p. 984): unconformity. The up and down movements of connected by means of the same or similar cir- “However, our opinion offers a means through base level coincide with the uphill and downhill cumstances of formation.” Walther recognized the correlation of facies to change the homotaxy “zig zag” movements of facies tracts and the con- that similar environments have similar [relative age equivalency] of the characteristic comitant cycles of vertical facies successions rec- processes, and will therefore produce similar fossils into a homochrony [equivalent age] of the ognized by Gressly and Walther. sedimentologic products. rocks. We have described this way briefly in the We now realize that base-level movements do Like Gressly, Walther (1894, p. 978) distin- section before, and this entire work is a guide- not involve transits across the Earth’s surface at guished between the genetic origin (process-re- book for the new way.” all geographic locations. In some places, at some sponse) of rocks (Gressly’s “facies”) and their It is in this explicit context of needing a times, base level oscillates up and down entirely time value (Gressly’s “terrain”), and he cautioned method of correlation that the “Law of the Corre- below or entirely above the Earth’s surface. several times that these two aspects of rocks must lation of Facies” is expressed. Walther adopted Where base-level oscillations are always above not be confused. He noted that “If we seriously Gressly’s Facies Laws which established that the Earth’s surface, sediments may accumulate at want to pursue the history of the earth…” (to facies transitions along depositional profiles are increasing and decreasing rates, and these cycles Walther, this is the primary objective of geologi- repeated in vertical facies successions. Walther are recognizable in conformable strata. cal study), “then we have to establish the ages of recognized that progradation resulted from accu- The critical issue is that Barrell recognized the rock units independent of lithology so that suc- mulation of sediment along the inclined surface metronome aspect of base-level cycling, and cessive paleogeographies can be reconstructed.” of a depositional profile, and provided a hypo- understood that the stratigraphic cycles produced Walther asserted that fossils alone are an inad- thetical example of sediment filling a fjord during by the uphill and downhill movements of facies equate means of establishing stratigraphic corre- a period of unchanging sea level. He understood tracts during base-level cycles were the basis for lations, and that correlation based upon physical that a necessary geometric consequence of high-resolution stratigraphic correlation. He also attributes of strata is essential (1894, p. 979): progradation is the downhill (or seaward) transla- understood that time was continuous and that

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time is fully represented in the stratigraphic 1958; see summary in Cross et al., 1993). This during base-level fall when accommodation record by the combination of rocks plus surfaces principle has been slow to develop and become space is decreasing. Consequently, there are spe- of stratigraphic discontinuity. The time repre- recognized and applied in stratigraphic analysis. cific and distinctive stratigraphic signatures of the sented by an unconformity at one geographic po- However, with the hindsight of history, we can different parts of base-level cycles. The sedimen- sition is represented by rock at another position. see hints of its recognition and usage during the tologic and stratigraphic attributes of facies tracts The next insight that completed the fundamen- past half century, particularly in Wilson (1967), commonly described in “facies models” and tal principle that stratigraphic base level is the ref- Curtis (1970), MacKenzie (1972), Wilkinson “depositional system models” are thus mixtures erence frame for the passage of time and the (1975), Galloway (1986), and Sonnenfeld and of attributes which existed separately during accumulation of sediment was contributed by Cross (1993). base-level cycles. Wheeler (1964). During the intervening half cen- Accompanying sediment volume partitioning tury, the term “base level” was used in numerous, are differences in stratal geometries, facies asso- ORIGIN OF GRESSLY’S IDEAS AND contradictory ways, but primarily in geomorphic ciations and successions, lithologic diversity, SOME UNANSWERED QUESTIONS rather than stratigraphic contexts. Barrell’s notion stratification types, and petrophysical attributes that strata are naturally divisible into stratigraphic of strata which are preserved within identical fa- Although biographies document Gressly’s life cycles that record the rise and fall of base level at cies tracts but in different portions of base-level (e.g., Stampfli, 1986, and references cited multiple frequencies went unchallenged, unmod- cycles. The term “facies differentiation” refers to therein), there remains considerable mystery ified, and unused. Wheeler brought the term back these changes in sedimentological and strati- about several aspects of his intellectual leaps to- to stratigraphy and introduced a different notion graphic attributes during base-level cycles. Fa- ward establishing a new philosophical approach of base level that was more appropriate for strati- cies differentiation reflects the degree of preser- and methodology of stratigraphy. Was the con- graphic analysis. vation of original geomorphic elements, as well cept that a facies represents the products of Wheeler considered stratigraphic base level as as the variations in types of geomorphic ele- processes operating in specific environments an abstract (nonphysical), nonhorizontal, undula- ments that existed within a depositional environ- passed along to Gressly (perhaps by Voltz; Gall, tory, continuous surface that rises and falls with ment at different times. 1976), or did he discover it through personal respect to the Earth’s surface. As base level rises, There are two principal categories of facies dif- observations of strata in the Solothurn Jura? If intersections of the base-level surface and the ferentiation. The first encompasses the changes in Gressly discovered the significance of relating seaward-inclined Earth’s surface move uphill. attributes of a single facies that occur during base- observed lithologic attributes to the processes This increases the area of the Earth’s surface level cycles. The deposits of a braided stream that that formed them, then how did he understand below base level where sediment may accumu- accumulate during low accommodation, for that association since he had no first-hand knowl- late, and increases the sediment storage capacity example, have limited facies diversity. By con- edge of a marine environment or modern marine in continental environments. As base level falls, trast, the deposits of a braided stream that accu- sediments until 1859? Did his understanding of the opposite occurs. Stratigraphic base level is a mulate during high accommodation have in- marine carbonate paleoenvironments come from descriptor of the interactions between processes creased facies diversity. In the latter case a greater literature, such as Charles Lyell’s Principles of that create and remove accommodation space, variety and a larger proportion of the original geo- Geology, or from his mentors and friends? Why and surficial processes that bring sediment to or morphic elements of the braided stream are pre- did Gressly not publish on facies and strati- remove sediment from that space. In effect, but served, although the geomorphic elements of the graphic correlation after his first and only paper not explicitly, Wheeler defined stratigraphic base braided streams were the same in both cases. on the subject? These questions are unanswered level as a potentiometric energy surface that The second type of facies differentiation is a despite considerable bibliographic and historical describes the energy required to move the Earth’s complete change in the types of facies and/or the research, some of which has been cited. Perhaps surface up or down to a position where gradients, facies successions that occur at the same position additional knowledge can be gleaned from study sediment supply, and accommodation are in along a topographic profile of deposition. These of his field notes and unpublished manuscripts, equilibrium (Cross et al., 1993). changes in facies assemblages reflect changes in stored in the Solothurn museum. Wheeler’s stratigraphic base level is the con- the geomorphic constituents of the depositional ceptual device that links several concepts: environment. A common example is the alterna- A LESSON FROM GRESSLY’S APPROACH Gressly’s facies and facies tracts; Walther’s tion of wave-dominated, open-ocean–facing notion of the “zig zag” uphill and downhill move- shorefaces during base-level fall, with tidal cur- A common perception in the practice of sedi- ment of facies tracts; Gressly’s and Walther’s rent dominated open bay, gulf, and estuary envi- mentary geology today is that variations in strati- identification that this movement is recorded as ronments during base-level rise. The geomorphic graphic architecture, facies compositions and regular vertical facies successions that define elements occur alternately at the same position assemblages, and petrophysical attributes of sed- stratigraphic cycles; Barrell’s notion that base- along the topographic depositional profile and at imentary rocks are complex, disorganized, highly level cycles are the clock of stratigraphy (and the same range in water depths. Essentially, the variable and haphazard “noise” of the strati- therefore that correlations based upon physical open-ocean–facing, wave-dominated straight graphic record. However great the complexity stratigraphy are possible); and the concept of sed- coastline is temporarily replaced during times of and variability in sedimentologic details, this per- iment volume partitioning. base-level rise and increasing accommodation by ceived “noise” must originate from the preserva- an embayed coastline, where wave energy is tion of varying proportions of original geomor- Facies Differentiation is a Product of Sediment dampened and tidal currents are enhanced. phic elements as strata. We are confronted today Volume Partitioning The degree of preservation is a consequence of with a similar problem to the one Gressly solved the ratio of accommodation to sediment supply. by carefully documenting all those attributes The last fundamental principle to be emplaced Sediment volumes and geomorphic elements are which he could master with the means available within the current stratigraphic paradigm is the more completely preserved during base-level rise at his time. concept of facies differentiation (Van Siclen, when accommodation space is increasing, than Using Gressly’s approach, this “noise” would

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be considered to have a high information content trends within a limited stratigraphic interval de- 2. Conchylian terrain or Muschelkalk 3. Keuper terrain or iridescent marls and a regular, predictable structure. Quantitative fine the regional paleogeography. II. Jurassic or Oolithic Formation measurements of sedimentological, biological, Gressly provided the shoulders upon which A)Liassic Group, subdivided into: and petrophysical attributes should provide infor- other giants of stratigraphic science have stood. 1. Lower Lias (sandstones of Lias and limestones mation crucial to unraveling the complex history After Gressly, there were five additional strati- with arcuate grypheas) of sedimentation. Examples of sedimentological graphic concepts that were added to complete the 2. Upper Lias or Liassic marls B)Lower Jurassic or Lower Oolithic Group, sub- attributes to measure include bedset thickness of current stratigraphic paradigm. (1) The strati- divided into: identical types of cross stratification; bedform graphic process-response system conserves mass. 1. Marly sandstone [written in English] and iron oolite diversity; frequency of shale partings; frequency (2) Sediment volumes are differentially parti- 2. Compact and subcompact limestones [dense mi- and amount of relief on scour surfaces; and degree tioned into facies tracts within a space-time con- crites and bioclastic] or Dogger 3. Dalles nacrées, rusty sandy limestones, Great of preservation of original geomorphic elements. tinuum as a consequence of mass conservation. Oolite [written in English], and marls with Ostrea Examples of biological attributes include micro- (3) Cycles of facies tract movements laterally (up- accuminata facies composition; faunal size; species diversity; hill and downhill) across the Earth’s surface are C)Middle Jurassic Group or Oxfordian, subdivided number of trophic levels; and reproductive strat- directly linked to vertical facies successions, and into: egy of populations. Examples of petrophysical at- are the basis for high-resolution correlation of 1. Oxfordian marls or Oxford Clay [the latter written in English] tributes include porosity, permeability, and capil- stratigraphic cycles. (4) Stratigraphic base level is 2. Terrain à chailles [cherty terrain] lary entry pressure. Recording of these attributes the clock of geologic time, and the reference D)Upper Jurassic or Upper Oolithic Group, sub- within a time frame given by the changes in frame for relating the energy of space formation divided into: accommodation should provide a clearer and co- with the energy of sediment transfer. (5) Facies 1. Coral terrain 2. Portlandian terrain herent picture of the details of stratigraphy. differentiation is a byproduct of sediment volume This classification seems to me to be the most nat- partitioning. Most of these concepts were added ural and most favorable for study of secondary CONCLUSIONS around the turn of the century. [Werner’s Secondary] stratigraphic units of regions that we are concerned with because it provides broader di- Amanz Gressly began geological field studies ACKNOWLEDGMENTS visions which are constant and avoids subdivisions that are artificial or purely local. It allows us to bring out in the Jura Mountains with the intention of map- better than any other complex descriptive system [clas- ping and correlating strata and reconstructing We thank Jean Paul Schaer and Marc Weid- sification] the essential characteristics of our strati- successive paleogeographies within the existing mann for reviewing our translation of Gressly and graphic units and their real relationships with analogs paradigm of Wernerian Neptunism. His careful for considerable insight on relevant historical and from foreign countries. Indeed, any descriptive system taken from foreign geologists and strictly applied to the observations caused him to recognize the invalid- biographical matters. Their shared enthusiasm for study of a given distant country can lead to serious in- ity of the tenets of that paradigm, which he jetti- this subject was stimulating. Michele Aldrich, conveniences [mismatches] which are easy to foresee soned, and he developed the foundation of the Gerry Friedman, and Gerry Middleton provided for the Swiss Jura and which has been a common expe- stratigraphic paradigm we have today. constructive reviews and directed our attention to rience. Commonly that which is perfectly true for a Gressly established the following stratigraphic some of the relevant literature. John Grotzinger broad stretch of country may not be appropriate for an- other area that is not very far away. And, it is only principles. (1) Sedimentary facies record the read the penultimate draft and suggested im- through careful study of all of the aspects of restricted processes and conditions of the environment in provements in the presentation. We appreciate areas, and then through comparison of several of these which they accumulated, and are interpreted by their help. Elf Exploration Production gave per- regions studied in this manner, that one at last arrives at analogy with modern environments. (2) Several mission to P. Homewood to publish this paper. general results. These results may allow a reasonable appreciation of the geological position [age] and more facies coexist at the same water depth and may or less probable equivalence [stratigraphic correlation] therefore substitute for each other as sediment APPENDIX. TRANSLATION OF “GEOLOGICAL of a particular rock [lithology], or a given stratal unit. accumulates through time. (3) The morphologies OBSERVATIONS OF THE SOLEURE JURA,” This should serve as a solid basis for a well established of fossil species reflect the physical and chemical PART 1, “DESCRIPTION OF TERRAINS WHICH and predictive knowledge of the manner, the condi- conditions of their habitat, but nuances in their COMPOSE THE FRAMEWORK OF THE JURA tions, and the laws of formation of these rocks and RANGES IN THE CANTON OF SOLEURE AND stratal units. (9/12–32). morphologies reflect evolution. (4) Certain fos- ADJACENT REGIONS” (GRESSLY, 1838) In the areas that I have studied, perhaps more so than sils are more useful for interpreting the environ- anywhere else, extremely varied petrographical or ment of deposition (“facies fossils”), whereas The mountain ranges which run through the Soleure paleontological variations interrupt at every step the others are more useful for establishing the age of Canton and all of northwest Switzerland are com- universal uniformity that was ascribed until now to the posed, as in the French and Bernese Jura, of alternat- different stratigraphic units in the different countries. a stratigraphic unit (“index” or “zone” fossils). ing hard and nonresistant limestones and marls which They [these variations] are even repetitive in several (5) Time-stratigraphic surfaces are defined by contain minor beds of siliceous, iron-rich, and other stratigraphic units [“terrains”], and cause astonishment beds that follow a depositional profile. (6) Facies minerals. The number of stratigraphic units repre- for the geologist who attempts to study the nature of our change transitionally in a unidirectional trend sented by these beds is greater, particularly in the north Jurassic ranges. (10/1–7) along depositional profiles, and this trend is re- of the Canton and in the adjacent areas of Argovia and Commonly, he [the geologist] will stop with surprise Basel Jura, than in the rest of the Swiss Jura. Besides in front of formations he thought he knew well for a peated in vertical sequence through a succession the various oolithic groups, older stratigraphic units of long time. Led astray by too much faith in accepted of beds (a working description of Walther’s the Triassic formation outcrop, showing sections of geological dogma, which often generalizes purely local Law). (7) Stratigraphic correlations based upon their tilted beds. These uplifted stratigraphic units in facts, he will perhaps be mistaken about characters lithologic equivalency are demonstrated invalid this area comprise the whole secondary [Werner’s Sec- which until then he thought belonged only to a given ondary, or stratified rocks] series from the variegated stratigraphic unit and to a subdivision in particular; he for the area he studied (and by extrapolation, this sandstones to the portlandian with a succession from even will be tempted to completely confuse several applies to all cases). (8) Stratigraphic correlations base to top as follows: (8/3–14) stratigraphic units going so far as to doubt their [sepa- must be based upon the time equivalency of I. Triassic or Conchylienne Formation, comprising rate] existence. (10/8–14) stratigraphic units, even if their facies differ. the following terrains: However, another more attentive study, more pro- (9) The depositional profiles and regional facies 1. Variegated sandstone terrain longed and above all more comparative, will show him

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how much the structure of our Jura is still unknown, ocean and the seas. At least, I often have been aston- the others having an extremely elastic structure which facts which will open a new road to geological research ished to find in the distribution of our fossils the laws gives and bends in the force of the waves but recovers and whose reach will only be measured when this of living communities and in the corresponding instantaneously, and comes out victorious from the in- research will have reached its full development and the assemblages of petrographic and geognostic character- cessant combat. The external morphology of the orga- results to which they lead will have been generally istics which correspond to the living communities, the nisms and the layout of their organs are no less appro- appreciated to their real value. (10/15–20) environmental conditions which rule in the submarine priate to the circumstances which govern their My intention was to apply to the country where I live world. (12/4–12) existence. Commonly all these properties are united to the geological laws that Mr. Thurmann verified with so Throughout the following descriptions of our strati- reach the objective. (13/22 to 14/10) much talent and success on the stratigraphic units of the graphic units, I will give my interpretation on the dif- One finds as a characteristic example diverse neighboring Bernese Jura; but soon I was forced to suc- ferent facies that I presume to be littoral—or shallow Crinoids which are supported on a long stalk which is cessively modify these laws according to the diverse marine—deposits, or pelagic—or deep sea—deposits, given elasticity and is more or less flexible through a regions which make up the Soleure Jura, and the study however, without ascribing more confidence than the number of articulated limestone disks which are held of these diverse regions necessitated on my part a sys- observational facts allow; because I expect to have to together by ligament fibers which are extremely flexi- tem of research [research method] different to the one modify some points later after I have studied the entire ble and are held inside a strong common epidermal which is generally practiced. Instead of being satisfied terrain of our Jura from Randen in the Canton of sheath. They attach to the sediment surface and any with a certain number of vertical sections as type sec- Schaffhouse right down to the last Jura ranges beyond body lying on it thanks to a large and ramified base or tions [“types descriptifs”], I followed each terrain along Geneva and from the Swiss [molasse] basin as far as the by holdfast. The Echinoderms above all those with its horizontal extent as far as possible in order to study foot of the Vosges in the French departments of Doubs, spheroidal test or with a flattened disk which are made all its variations. (10/21–29) Jura and Haut-Saône. (12/13–22) up of a multitude of plates which are joined together In this way, I have come to understand that within I intend to return later to a more precise discussion and can therefore support shocks abound in extremely the areal extent [“dimension horizontale”] of each ter- of this subject after a deeper study of all the details of varied species such as Cidaris, Diademia, and the rain, there are several well-defined variables which the combination of the paleontological constitution of Clypeastreas. The Spatangoids with the thin shell are to show the same features in petrographic composition as our stratigraphic units and the phenomena within the the contrary almost entirely absent. (14/11–22) well as in the paleontologic attributes of their fossil marine environment today will allow me to judge with Among the Bivalves, there are genera of which a content, and which are governed by specific and fairly greater assurance and to give more justified opinion on large number are solidly affixed to the substrate and constant laws. (10/30 to 11/3) these relationships. (12/23–28) other fixed objects. Among these are the Ostreas and Above all, there are two major facts which define In the meantime, it is perhaps not out-of-place the Spondyloids with a large basal foot and a strongly everywhere the sum of the variables which I call facies briefly to comment on my present way of understand- crenulate shell having many spines which help to an- or the aspects of a stratigraphic unit: one is that within ing the correlations between the geognostic constitu- chor them to various objects on the seafloor. Others a stratigraphic unit the occurrence of a specific lithol- tions of stratigraphic units [the attributes allowing geo- with a weaker shell lived in cavities, either those that ogy necessarily also requires the occurrence of a spe- logical interpretation] and the fossil assemblages they happen to be there or those which were excavated by cific paleontological association; and the other is that contain. (12/29–31) them within hard substrates. These are the Arcacea and a given paleontological association rigorously ex- First of all, all the rocks of the sedimentary terrain of the perforated genera such as Lithodomes and analogs cludes those genera and species of fossils which are fre- our Jura come under two main types: A) those which by to the Saxicavea, Venerupis, etc. Others protect them- quent in other facies. (11/4–10) their structure are essentially mechanical from a high selves from the strength of the waves either by hiding in If, by chance, certain genera and species which char- energy sea, for instance, breccias, coarse oolite sand muddier environments sheltered by Corals and acterize a specific facies are found in another facies, it is coquinas; B) or rocks which according to their structure Crinoids, such as the Astartes and analogs, or by an a general rule that specimens of these genera and are essentially chemical in origin from low energy seas, excessive development of the carbonate shell like the species will be much rarer, less developed and less for instance marls, marly limestones, fine grained lime- Trichites, the Chamacea (Diceras), the Pernes, and characteristic than in the facies or general assemblage stones, homogeneous limestones, more or less pisolitic some of the transition species of the muddy facies. to which they normally belong. Similarly, wherever the limestones, and pisolites [perhaps oncolites] which Finally, others escaped the destructive attempt of the geognostic characteristics of a facies [indicators of grade into the matrix. (13/1–10) ocean by the high elasticity of their shell such as the inferred depositional processes or environments] are These two end member rock types, either pure or Pectinids, the Limas, and the Terabratulids which in best developed, the paleontological assemblages also mixed, constitute well defined facies, according to their addition were supported by a strong ligament holdfast are the best expressed, the genera and species are most petrographic characteristics, which vary according to in the form of an elastic tendon. (14/23 to 15/8) numerous and individuals are most typical, best devel- their littoral or pelagic depositional environments. Gastropods of the coral facies have the identical char- oped, and are commonly in a perfect state of preserva- Their paleontological features are no less distinctive acteristics to the previous order. In particular, one finds tion. If the facies show intermediate characteristics with and always correspond even in the slightest detail to the the Turbo, Trochus, Pleurotomaria, some Nerinea, and a mixed geognostic features, the fossils also share less geognostical [e.g., structure, bedding, and stratifica- fairly large number of species of genera analogous to typical attributes. In this case they are generally rare, tion] and petrographic features, as we will see in what Monodontes, Patellas, Buccina, etc. Crustaceans, poorly preserved, poorly developed and belong to few follows in treating each terrain in detail. I will only although not common, are not absent, in particular those genera and species; however, there are occasional well- show here the major facies which are constant through- close to the Pagurea, of which one only finds the strong formed fossils which belong mostly to different species out all our stratigraphic units as far as I know their ex- pincers. To the contrary, Cephalopods and fish are rare; than those in the principal facies or which rarely occur tent through my own observations, all the more so in apparently reptiles are totally absent, and when they are in them. (11/11–26) that the more or less numerous local and transitional found it is only by accident. Serpulids heavily encrust all I will insist on these strange facts [i.e., paleontologi- subfacies can easily be linked to the major facies. bodies both organic and inorganic. (15/9–19) cal and petrographical aspects related to facies] in the (13/11–21) One very important characteristic which is universal description of each stratigraphic unit that will be studied Breccias, coquinas, oolites, pisolites, mostly coarse to organisms within the coral facies is a very thick shell, successively; because they seem to me to repeat at grained, constitute the coral facies and associated de- always highly ornamented by ribs, striations, spines, another scale and in different relationships a law similar posits such as reworked sediment and immediate tran- nodes, and other ornamentation giving a strange, very to the one which governs the larger scale stratigraphic sitions to muddy facies. These rocks always show the particular physionomy, very irregular and useful for divisions. The subtle variations in faunal assemblages, characteristics of littoral and shallow marine deposits determining the niches they occupy in an ocean long related to lateral facies transitions, play a similar role and only contain fossil assemblages which are charac- gone from the surface of the earth. (15/20–26) within each small-scale time-stratigraphic unit, albeit on teristics of coral beds, mainly composed of fixed mas- The coral facies comprises several subfacies, which a vastly different scale, to that played by fossils of gen- sive or branching corals, which resists the shock of vary in the different stratigraphic units and regions of uine stratigraphic value (such as the knotty Ammonite, waves and which living genera and species such as the our Jura, and which are useful to know in order to the arcuate Gryphea, the Baculites) vertically within the Agaricias, Astreas, Oculinas, Caryophyllas, etc., today understand the laws of distributions of paleontological larger-scale lithostratigraphic units. (11/27 to 12/3) build coral banks and reefs in tropical seas that are so associations. These subfacies are explained as transi- I think that the petrographic or paleontological dangerous to ships. These corals always are accompa- tions which link the major facies, and allow apprecia- changes of a stratigraphic unit in the horizontal are nied by other organisms common to coral reefs, which tion of the slightest nuances in the living conditions of caused by the changes in environment and other cir- appear to flourish in high energy, agitated water, thus the organic world now buried in the earth’s crust. Thus cumstances, which still so powerfully influence today always giving a morphology that provides resistance to coquinas link petrographically the purely coral facies to the different genera and species which inhabit the the waves, the ones being firmly fixed to the substrate, the purely muddy facies, passing through the ooliths

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and pisoliths, to the sandy and gravelly varieties [mix- although they are not really abundant elsewhere than in rather difficult, at least in our Jura, because this facies is tures] of the muddy facies. Analogous passages from the muddy littoral facies. (16/27 to 18/3) so closely linked by imperceptible transitions to the true one paleontological assemblage to another always ac- A general trait, which is constant for all paleontolog- pelagic facies, if this facies could develop in the almost company these petrographic transitions. It is always the ical assemblages of the muddy facies, is that the domi- universal oceans of these ancient times, which were most delicate [“gracieuses”] forms which dominate in nant genera and species have tests less apt to resist certainly much less deep than the Ocean and the seas of the transition zones. (15/27 to 16/7) destructive effects of reworking. The shells, among oth- today.—Whatever, it is sure that with the appearance of Reworked deposits, although closely related [spa- ers, are normally very thin, very much smoother, less or- the spongy corals, the fossils of the littoral facies suc- tially] to the coralline facies from which they mostly nate, less ornamented with different protuberances than cessively disappear as one goes away from the ancient come, accompany and link all the facies, and don’t in the preceding [coral] facies where they have a very Vosges and Hercynian shorelines. In contrast, Belem- have, apart from a few genera of fossils which inhabit pronounced massive resistant character. However, there nites and large Ammonites become more frequent, but loose substrate, any characteristic zoological assem- are sometimes genera and species with very thick shells they are very different from the littoral species (Macro- blage. They inherit, according to circumstances, some but which have a less robust structure and which easily cephalus and Planulates), whereas those of the littoral of the characteristics of the adjacent facies, receiving delaminate and disaggregate by abrasion. (18/4–13) muddy facies are the Falciferes, Arietes and Ornates. various fossil fragments which diminish in size as they These phenomena are very obvious in the genera Belemnites show similar modifications but less easily are transported farther from their original habitat, and species which are transitional from the coral to the deciphered because of their unornamented shell. Of all finally to constitute an oolite [probably coated grains as muddy facies: thus the Trichites, the Pernes, and several the other organisms which are so abundant in all the opposed to ooids] or become entirely decomposed other species, commonly have an enormously thick littoral coral or muddy facies, there are now only a few [lime mudstone or wackestone]. Using this observation, shell in the coral facies, whereas they only have a rela- Terebratulas, a few Ostracea and other similar fauna I have managed several times to follow the increase of tively thin test in the muds; similarly the Limas and the which seem to adapt to each given environment, but debris size and conservation to find the original habitat. Pectinids, which are variously ornamented in the which show more or less obvious variations, the study There, one finds the fossils in place, with a prodigious coralline facies with ribs, striations and spines, are gen- of which should lead to very interesting results on the profusion and so well conserved that one can study the erally almost smooth in muddy deposits, without talk- biological laws of ancient creations. (19/15 to 20/21) most minute details of the organization and characteris- ing about all the other remarkable differences which After having determined the major facies which tic assemblage, the behavior and habits, as we will see relate to their behavior in the different environments dominate our Jurassic terrains, it remains to take a look in the following descriptions of terrains. (16/8–26) where local processes still too poorly known to be more at the laws which underlie and control their distribution The muddy rocks, such as marls, compact and sub- precisely stated strongly influence the distribution and both vertically and horizontally. (20/22–25) compact limestone, finely granular and subcrystalline the structure of fossil organisms. (18/14–24) The facts that I have given above result in this first limestone with rare small ooids, passing gradually into Another distinctive characteristic of the fossils of the law: (20/26–27) concentric pisolites that are similar in composition to muddy facies is that they are almost exclusively free Each facies of a stratigraphic unit has its own dis- the matrix, [oncoids] sandstones, sands, etc. compose a living genera and species. Even the Pentacrinids in tinctive petrographic and geognostic or paleontologic second major facies, which is just as important as the these facies have never shown any trace of holdfasts, attributes which do not represent the characteristics of preceding one, either from its extent within the Jura, either their more or less lengthy stalk only has its lower the entire stratigraphic unit, nor the attributes of the which is much larger than the other, or according to the extremity stuck in the mud, or they are held in place by other facies forming the same geological level [strati- paleontological assemblages, which are radically dif- extremely reduced byssal fibrils either in the mud or graphic interval]. (20/28–32) ferent from the coralline facies. This facies is character- onto other objects lying on the seafloor. The spongy This law will help correct the classifications of ized geognostically by thinness [stratigraphic attribute] corals appear to behave similarly. (18/25–32) many stratigraphic units and their subdivisions by particularly in the nearshore parts, by the high variabil- Another facies of the muddy type belongs to the defining more precisely their position [stratigraphi- ity of the deposits [lithological diversity] caused by subpelagic and pelagic environments which has simi- cally and geographically], and will therefore avoid the local processes which in several stratigraphic units have lar petrography to the littoral facies but differs by the serious mistakes in determining the geological level of given rise to numerous subdivisions [formations] which characteristic fossil assemblage and by geognostic localities [correlation of stratigraphic intervals] which are only of interest for restricted areas. One rarely finds phenomena. (19/1–6) are separated by large rock bodies with different char- corals which are sponge-like genera and species which The pelagic deposits are very constant, homo- acteristics. (21/1–4) encrust and generally lack an obvious basal holdfast or geneous, regularly stratified, very continuous or massive A second law is intimately linked to the first: (21/5) with a very weak base when it does exist. Crinoids are beds, very thick, lacking obvious structure; however, Facies having the same petrographic and geognos- rare, spread out, and belong to mostly to free-living there are certain local exceptions to these features, for tic attributes show extremely similar paleontological forms. Echinoderms are a little less rare in particular the example, when reworked deposits cause perturbations characteristics throughout the stratigraphic succession real Echinus and related genera. The Spatangoides are and make the phenomena more difficult to decipher. [“terrains”], and occur in similar sequence through a everywhere in the muddy rocks, but more in those Other causes unrelated to neptunian processes and variable number of superposed stratigraphic units. which are gravelly to sandy than in the genuine which are not yet understood or which can only be sus- (21/6–9) mudrocks. Asterids such as the genera Asteria and Sac- pected [diagenesis?] seem also to have strongly modi- I find this law to be of great interest with respect to cocoma, are characteristic for the genuine mudrocks, as fied these deposits during deposition. (19/6–14) the zoological [taxonomic?] determination of fossils well as for the fine gravels and sands. There is What is most characteristic of these deposits is the and the use of taxa for paleontological characterization commonly a prodigious quantity of free bivalves almost complete lack of fossils over vast areas. As for of stratigraphic units and their subdivisions. There is (Acéphales) in particular Solens, Pholadomya, Myop- corals, one only finds debris of fixed corals that have commonly great similarity between the morphologies sis (Ag.), Jambonneaux, Tellina, Mytilus, Modiola, been worn and broken by rolling, or very poorly devel- of fossils of analogous facies, although they belong to Corbula, and the analogs to the Isocarda, Cucullea, etc.; oped individuals; there are more numerous spongy very different stratigraphic units, and this resemblance a large number Ostracea amongst which one can distin- corals with weak and soft fibrous tissue. It is generally has largely allowed the identification of many fossils in guish flat oysters which are weakly attached or free, accepted that these corals live at great depth, however, many terrains; this has led to a general concept that Grypheas, and Exogyras, which are entirely free or there is still doubt on this subject. In our terrains, they there are identical fossils not only in different subdivi- fixed. Among the Gastropoda most common are the [deep water corals] are found at the transition between sions and groups of terrains, but even in formations sep- Rostellarias, the Pterocerids, Natica, and analogs to deep sea facies and littoral facies, more than in the arated one from another in the vertical stratigraphic col- Turritella and Fasciolarids; among the Cephalopods, pelagic facies strictly speaking. Some regions and lo- umn by other very thick and extensive [“très-vastes”] some Nautiloids, very diverse Ammonites and Belem- calities even make me think that these zoophytes, under formations. A striking example of this sort, among oth- nites, all rare or frequent, depending on the strati- given circumstances, also lived on the muddy bottoms ers, is given by corals and Echinoderms, which graphic units and subfacies. Serpulids are rarer than in of localities that were sheltered from high waves such although very similar at first glance, show to a well- the previous facies. Crustaceans are represented by the as in narrow and sandy gulfs and places behind coral trained anatomical zoologist very marked differences genera Glyphea and analogs. Fish with broad flat teeth reefs. In this case, they are always accompanied by for each group [of fossils] and each stratigraphic unit in are characteristic of the mudrocks. Reptiles are found more or less abundant fossils which are characteristic of our Jura. Without wanting to solve the question of particularly in the Upper Jurassic terrains, but they are subcoral and muddy littoral, such as free-living shells whether some fossils pass from one terrain to another, restricted to certain regions and isolated locations more and certain Crinoids (Eugeniacrinus) and particular or even pass between stratigraphic groups, I would like than being ubiquitous. Their debris characterize above Echinoids. One could separate this assemblage from to underline an important fact which has not been much all the shoreline fringes of all Jurassic stratigraphic the pelagic facies under the name subpelagic with considered that the external morphology of living units and thus follow less strictly the facies laws, spongy corals facies. But this separation will always be organisms is always intimately related to their life envi-

1628 Geological Society of America Bulletin, December1997

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ronment, which Mr. Agassiz has demonstrated with only constitutes a very thin, irregular boundary between a single major work the series of memoirs that will be perspicacity in his lectures. (21/10–30) the pelagic deposits and the large Jurassic bay of the de- published in succession on the geology of the Jura What I have said about vertical succession of facies partments of Doubs and Haute Saône, which is almost Mountains carried out by people united in a single and is not without exception, and it is obviously natural that entirely filled by littoral deposits which gradually thin same goal to increasingly understand the geological this law should vary according to the petrographic from the Swiss border to the foot of the Vosges,showing phenomena of our Jura which over the past few years aspects and geognostics of rocks and stratigraphic paleontological characteristics which are increasingly has become so important to science. (25/10–22) units. We should thus not be surprised to find within a littoral in all the terrains. (23/7–30) I will divide rocks into formations, groups and ter- muddy rock above or below a coralline rock fossils The other zone which is pelagic, begins in Argovia rains, allowing further subdivision when necessary. which live in mud. But these fossils of the muddy facies and forms a less broad swath comprising the ranges of Each of these divisions, clearly characterized both by will indicate no less than the corals a shallow marine or the Soleure and Bernese Jura which lie on the edge of petrography and paleontology, will be intimately littoral environment even though these rocks are of a the Swiss basin and the Tertiary valleys which run in to linked. A brief abstract will precede the description of different type according to their depositional process. it. This swath is broader in the Canton of Neuchâtel each formation, and in a similar fashion a synopsis will (21/31 to 22/6) and would seem to comprise the whole of the Vaud and briefly characterize each group and each terrain with its The distribution of facies either in the horizontal or in Geneva Jura which only show enormously thick Port- different facies. Synonyms will indicate the equivalent the vertical obeys other no less important laws. (22/7–8) landian domes [anticlines] with very few fossils. terrains, divisions and facies of foreign countries if they Sometimes lateral [“horizontal”] facies transitions (23/31 to 24/5) exist and if they have been clearly described by geolo- are abrupt, sometimes the transitions are gradual and The subpelagic facies tract is intermediate between gists. A listing will indicate the geographical area of one facies passes into another through intermediate va- the littoral and pelagic facies tracts, and forms a transi- different stratigraphic units in our country. Finally, we rieties whose transitional features are poorly expressed, tion zone more or less closely linking them. In the will study the rocks themselves from two points of which together with the mixing of end-member facies, Canton of Schaffhouse and in Argovia this facies tract view, petrographic and geognostic. Thus we will have: makes it difficult to separate them. (22/9–13) predominates with respect to the others, sometimes be- (a) a petrographic description which will give min- Abrupt facies transitions are particularly obvious ing more littoral, sometimes being more pelagic, going eralogical composition and petrographic attributes of between coral dominated facies and pure muds, above from the Portlandian to the lower oolite through the our rocks such as structure, attributes of a freshly bro- all when the coral beds are surrounded by subpelagic or Coralline Terrain and the two stratigraphic units of the ken surface, colors, cement, matrix, etc. These charac- pelagic deposits. In other cases this transition is more Oxfordian. It is typically developed in the Soleure teristics, of which incorrect use has been very damag- gradual and much less perceptible. This happens par- Canton and everywhere shows numerous Cnemidium, ing to the progress of geological knowledge, are no less ticularly between coral and muddy littoral facies which Tragos, Scyphia, etc. It is also shows the same features extremely important in determining the different facies are commonly interspersed, as if their characteristics in the Neuchâtel Jura, etc. (24/6–14) of an entire formation, a group, a terrain, or even a sin- radiated from the centers or nuclei of rich organic It is very remarkable that all the reentrants along this gle bed, as we have previously seen by taking a rapid growth out to the periphery which only shows broken trend correspond to similar reentrants in the Jurassic look at the petrographic composition of facies. debris or a few undifferentiated or poorly developed shorelines along the Black Forest and the Vosges. For (b) a geognostic description, which will cover the fossils. (22/14–23) example, there are the reentrants of the pelagic facies in phenomena of our rocks as a whole such as stratifica- Diversity of the facies increases in a vertical direc- front of the Alsatian Gulf and the Bay of the Haute- tion, bedding, etc. These phenomena are more or less tion from base to top throughout the whole series Saône. (24/15–19) constant for each different facies; for example pelagic [stratigraphic succession through the Jurassic] and, This manner of studying and interpreting the com- facies or reworked deposits are characteristically mas- conversely, diminishes gradually in the opposite direc- position of terrains, I find gives the following obvious sive or thick bedded [“grande puissance”], whereas lit- tion.” This law presents some very curious phenomena: advantages. toral deposits are less massive or thinly bedded. (25/23 in the lower part pelagic facies of muddy type predom- 1st. To reduce the extremely varied paleontological to 26/18) inate and the other facies only start to appear in a dis- phenomena, which seem haphazard and without obvi- Paleontology will provide us with the principal char- tinct manner from [at the stratigraphic position of] the ous coherence, to a limited number of very simple laws acteristics of both large subdivisions and of facies. Lower Oolite, which has features showing neither which are closely linked between each other and which Study of fossilization and the substances which fos- pelagic nor littoral characteristics but an obscure mix of relate to the mechanical aspects [process dependent silize organisms, the state of preservation, and the dis- both. We shall soon see what controls this phenome- physical aspects] of petrography and geognostics. tribution of fossils and their assemblages will provide non. (22/24–31) 2nd. To explain all these petrographical and geog- observations and specific correlations with petrograph- Moreover, in some cases, following a considerable nostic attributes contained in sedimentary rocks, mak- ical features as also found between different groups and [thick and laterally extensive] pelagic deposit, littoral fa- ing them useful to science by carrying them from the stratigraphic units and various localities. (26/19–24) cies appear abruptly, almost without any gradual transi- realm of sterile [purely descriptive] mineralogy to the Use of specific rocks and minerals from each terrain tion. This phenomenon, although infrequent, once again realm of geology by showing their relationships with in technology, in agriculture, and their quarrying will begins at the Lower Oolite. It coincides with the abrupt the progressive development of life as is manifest at the not be forgotten, although the context of this geologi- or gradual horizontal facies transitions of the strati- different epochs of the history of our planet [evolution]. cal essay will not allow lengthy commentary on this graphic units which I pointed out previously. (23/1–6) 3rd. To be able to deduce with reasonable precision subject. (26/25–28) The diversity of facies is more or less constant in dif- the relief of the seafloor [depositional profile] at various ferent regions. The diversity increases in the regions times until it becomes emergent, and also the various where the French and Bernese Jura pass to the Argovian events which occurred in the ocean and which affected REFERENCES CITED and Wurtemberg Jura; but once past this boundary the stratigraphic units and facies with higher or lower energy. 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