The environment in which various parts of the Quinault Formation were deposited is fairly well indicated by the contained Foraminifera. Fortunately, many of the species are living, or are represented by morphologically similar forms in the seas today, particularly along the eastern Pacific. Therefore, by examining the known distribution of these species, it is possible to infer, at least in a broad way, the thermal conditions and particularly water depths under which groups of species or assemblages of the Quinault Formation most likely lived. Considerable data have been assembled on the occurrence and distribution of living Foraminifera off the west coast. Probably the first records of such information extend back to those of Brady (1884), in which he reported on Foraminifera dredged during the voyage of the Challenger in 1873-1876. Since that time many other contributions have been made. Outstanding among early reports is that of Cushman (1910-1916), in his monograph on the Foraminifera of the North Pacific. During the past 20 years or so a number of additional studies have been made on the occurrence and distribution of living Foraminifera in the eastern Pacific. Reports on many of these are organized in such a manner as to be particularly helpful in determining the representative paleoecology of faunas contained in Tertiary strata of the west coast. Among these, reports by the following are especially useful, and therefore they have been relied upon extensively in the present study: Bandy (1953), Cooper (1961), Crouch (1952), Cushman and Todd (1947), Enbysk (1960), and Natland (1957)
Although some species are found widespread throughout much of the Quinault Formation, the faunal composition of each section is varied. However within each section the composition is relatively uniform, at least to the extent that the fauna of each section most likely represents a reasonably similar environment of deposition throughout. Therefore, in the following discussion, the ecological significance of various species is discussed separately for each section. Those species found consistently throughout a section obviously were best adapted to the prevailing environment of deposition, and therefore their known present-day distribution is of greatest interest. However, some species occurring in a limited number of samples may also be of importance, particularly if their present-day distribution varies from that of the more commonly occurring forms. These species may support evidence for redeposition of sediments before complete consolidation, as is indicated by the sedimentary features of some in the strata of the Quinault Formation.
Foraminifera from this section (checklist, p. 20) almost certainly indicate a neritic environment of initial deposition. This conclusion is borne out by the present-day distribution of the five most commonly occurring species of this section:
The first of these, B. irtusitata, is known in Puget Sound and off the Washington coast today, where it is recorded almost entirely from neritic depths (0 to 600 feet). Furthermore, it, together with B. frigida (Cushman), a similar form, is largely confined to northern latitudes, where water temperatures are cool to cold. Cassidulina limbata is a widely known species along the eastern Pacific today, where it occurs largely in lower neritic depths (125 to 600 feet), but is also known down to a depth of at least 900 feet in southern latitudes. This species is particularly common in neritic assemblages from California northward to Alaska. According to Natland (1957), it is common within temperature ranges of 13° to 8.5° C. Records of C. fletcheri are mostly from off southern California, extending northward to Cape Blanco, Oregon, at littoral and neritic depths down to at least 100 feet in temperatures ranging from 17.5° to 13° C. Elphidium hughesi, although not known in today's seas, is similar to several Recent species well-known off the west coast. One of these, E. articulatum (d'Orbigny), is a common and widespread element along the coast in upper neritic depths (0 to 125 feet) at temperatures between 21° and 13° C. (Natland, 1957). According to Enbysk (1960), E. tumidum Natland and E. translucens Natland are recorded from depths between 0 and 125 feet along the coast from Alaska to Oregon, where temperatures are at least as low as 7° C. at times. Ephidium translucens, therefore, apparently indicates wide tolerance for temperatures, as Cooper (1961) records E. translucens from beach and tide-pool deposits throughout the coastal area from San Diego to the Columbia River, where temperatures average considerably higher than in Alaskan waters. The frequent occurrence of G. bulloides, a planktonic form, does not infer a great deal about water depths. However, it does suggest open-sea conditions. Its presence may also generally suggest temperate to cool water conditions.
A second group of species listed below, although not found as frequently as those listed above, do represent a substantial part of the total foraminiferal fauna of this section:
With the exception of E. pacifica, records of all these species are nearly confined to neritic depths along the eastern Pacific. Most are widespread along the coast and suggest a wide tolerance for temperature. However, records of both O. borealis and Q. akneriana suggest that they favor temperate to cool water temperatures. Polymorphina charlottensis, a less commonly occurring form, further substantiates temperate water conditions. The distribution of E. pacifica in the eastern Pacific is in noticeable contrast to that of all other frequently occurring forms of the section, in that it is known largely from middle and upper bathyal depths (600 to 3,000 feet) in temperatures ranging from 8.5° to 5.5° C. It is also known from depths approaching 7,000 feet in temperatures down to 1.9° C. Although this relatively common form is the only one that suggests substantial depths, several other, less common species, such as Uvigerina senticosa and U. subperegrina. occur rarely in a few localities of the section.
In view of this relatively minor evidence, the possibility of redeposition of at least some of the sediments to a deeper environment should not be overlooked. It is perhaps significant that all deeper water elements are confined to the lower half of the section.
In summary, therefore, the preponderance of foraminiferal evidence suggests that the section of Quinault Formation exposed north of Point Grenville was originally deposited in neritic depths (0 to 600 feet), and most likely was confined to depths of not more than 200 feet. Water temperatures were probably temperate to cool (13° to 8° C.), much like, or possibly slightly warmer than, those along the present-day Washington coast. In addition, lesser evidence suggests that redeposition of at least some of these sediments may have been to bathyal depths, not necessarily deeper than 1,500 feet in cold water.
The foraminiferal fauna of this section, shown in the checklist, page 20, is in some respects similar to that of the section north of Point Grenville, but differs in that it contains noticeably more species with affinities for deeper water conditions. Those species occurring in a large majority of the samples from this section are listed below:
Buccella inusitata and C. limbata, as mentioned previously, are distinctly representative of a neritic environment and together tend to favor temperate to cool water conditions. According to the records, C. mckannai or morphologically similar forms are somewhat rare from the Recent seas off the west coast, but a few are known only from deep water (bathyal) environments. Globigerina bulloides, as stated previously, suggests temperate to cool water in open-sea conditions. Similar conditions are also suggested by G. pachyderma. Ingle (1.967) reports, and his conclusion is supported in the collection of the present study, that sinistral coiling of this form is dominant in the section south of Taholah. According to Ingle, such coiling suggests temperate water conditions. In addition, records of Enbysk (1960) substantiate this conclusion in that the species is reported as common from numerous localities in the northeast Pacific. Probably the most noticeable difference between the fauna of this section and that of section north of Point Grenville is the presence of a substantial number of Uvigerina. Although U. juncea is the most commonly occurring species of this genus; in general, all other species can be considered together with this form, as all those present indicate essentially the same conditionsmainly deep, cold water. Uvigerina juncea is common today off the coast of Washington and Oregon in lower neritic to upper bathyal depths (Enbysk 1960). Bandy (1953) reports U. hollicki Thalmann, a similar low-costate form, from depths ranging from 400 to 700 feet in water temperatures between 13° and 7.4° C. off southern and central California. Uvigerina subperegrina, a coarsely costate form, although not among the most commonly occurring species of this section, is present in a number of the collections. This species is similar to today's commonly occurring U. peregrina Cushman, which distinctly prefers bathyal depths. In the northeast Pacific it is typically common from depths between 600 and 6,000 feet. Off California, Bandy (1.953) records it from 1,200 to 2,400 feet in water temperatures ranging from 6.6° to 4° C. Natland (1957) lists this species as characteristic of his biofacies IV, which prevails at depths between 900 and 2,000 feet at temperatures between 8.5° and 5° C. in eastern Pacific waters. He also states that the upper boundary of this biofacies apparently is controlled somewhat by temperature, because off southern California the 8.5° isotherm is at 900 feet, while off Panama it is at 1,500 feet. However, he further points out that other factors must enter in, because northward the 8.5° isotherm is at sea level in Alaskan waters, but the form is not known there in shallow water. It would, therefore, seem that the presence of coarsely costate Uvigerina such as U. peregrina and U. subperegrina is somewhat indicative of bathyal depths in waters not exceeding 8.5° C. Other species occurring less frequently in this section but still found in a substantial number of samples are listed below:
Forms such as E. hughesi, as previously mentioned, distinctly prefer shallow neritic depths. The records of Nonionella such as N. miocenica are largely from neritic environments, favoring warm to temperate water conditions. Pullenia bulloides, similar to P. miocenica, is, according to Natland (1957), one of a group of species found typically at substantial depths (4,000 to 7,500 feet) in cold water (3.2° C.) in many deeper parts of today's seas. As previously mentioned, Q. akneriana apparently favors neritic conditions in temperate to cool water.
In view of the known present-day distribution of the most commonly occurring Foraminifera of the section south of Taholah it appears most likely that more than one condition of deposition is represented by the fauna basically, a shallow water or neritic depth in perhaps temperate water conditions, and bathyal depths in cold water. From the known distribution of Foraminifera in the eastern Pacific of today, it would be difficult to find a single condition satisfactory for the entire foraminiferal fauna of this section. Faunal evidence is, therefore, strong for redeposition of at least part of the section. Moreover all evidence exists, perhaps, for deposition at neritic depths, but the bathyal element is strongly significant also. Therefore, the beds as we see them today were most likely deposited at upper bathyal depths, perhaps 900 to 2,000 feet in cool to cold water (9° to 4° C.), but much of the material was derived, possibly in part as the result of turbidity currents or even by normal current action, from materials originally deposited in a neritic environment of perhaps 0 to 600-foot depths in temperate water conditions. The comparatively fine-grained nature of the sediments suggests deposition in an area well removed from the source of material, and therefore supports the faunal evidence for deposition well offshore.
Based on the few Foraminifera found (checklist, p. 20), the strata in this section almost certainly were deposited in shallow water. Although numerous samples were taken from localities well distributed throughout the entire section, unfortunately, Foraminifera were found in limited numbers of species, as well as of individuals, from only seven widely spaced localities. Furthermore no specimens were found in the uppermost conglomerate part of the section. Therefore, the Foraminifera are not greatly useful for determining details about the ecological conditions under which the beds of this section were deposited. However, the available evidence is consistent in that the eight species all definitely occur, or have some similar living form, in the present-day littoral to upper neritic environments along the west coast. Most frequently occurring, and therefore of greatest significance, is Elphidium hughesi. As previously mentioned, similar forms are found today typifying littoral and upper neritic conditions rather widespread along the west coast in temperatures varying widely from perhaps 21° to 7° C. Other species from scattered localities throughout the section are:
Because all these species were found in very limited numbers, they alone are not greatly significant with respect to the probable ecologic conditions under which the strata of this section were deposited. However, it is noteworthy that the known distribution in the seas today of all these or similar species, except the planktonic G. bulloides, is essentially confined to upper neritic or littoral conditions. Because no deep-water Foraminifera were found in this section, foraminiferal evidence is lacking for secondary transport of these sediments from shallow to deep water. The lack of Foraminifera in much of the section, particularly the upper part, suggests brackish, or possibly even partly nonmarine, conditions. Based on lithology, together with the distribution of Foraminifera, as well as a few scattered molluscan fossils in the lower part, water depths may have been greater (possibly upper neritic) during the deposition of the lower sandstone and siltstone part of the section, whereas littoral or beach deposits are most likely represented by the carbonaceous conglomerate and coarse sandstone of the upper part of the section.
The Foraminifera from this section (checklist, p. 20), as a group, firmly indicate a neritic environment of deposition. Some sixteen species, or groups of species, constitute most of the Foraminifera collected from this section. Of these, at least half are largely confined to, or at least show a decided preference for, a neritic environment in the eastern Pacific of today; these species are listed below:
The present-day distribution of B. inusitata, C. fletcheri, F. basispinatum, O. borealis, and N. miocenica, as already discussed, indicates a preference for neritic depths, particularly a lower part of this zone. Furthermore, most of them suggest rather wide-ranging temperature conditions. However, B. inusitata and O. borealis indicate a preference for cool water. Records of C. fletcheri are rare in the northeast Pacific, and are largely confined to coastal waters off California and southward in relatively warm temperatures, possibly between 17.5° and 13° C. This species, together with C. conoideus, a similar form not known, or at least rare in Recent deposits, constitutes a very persistent-occurring element in the Duck Creek-Pratt Cliff section. Angulogerina semitrigona is present today in Puget Sound and off the coast from Alaska to Oregon (Cushman and Todd, 1947; Enbysk, 1960), where it is found largely at lower neritic depths in temperatures ranging from 13° to 5° C. Records show that B. elegantissma is confined mostly to neritic depths in the northeast Pacific, but is also found deeper in southern latitudes. This distribution suggests that it may not have a tolerance for warm water. However, Natland (1957) lists it as characteristic of his biofacies I, which he indicates represents a depth of 0 to 20 feet, having a wide temperature range of 24° to 5° C. He further states that it is known down to 580 meters. Pullenia salisburyi is common in the northeast Pacific largely at lower neritic depths, but is also known from the upper bathyal zone (1,200 feet). The available records, therefore, suggest that this form may well have a preference for cool water. Most of the remaining commonly occurring forms of the Duck Creek-Pratt Cliff section show a preference in today's seas for lower neritic to upper bathyal depths; they are listed below:
Records of C. islandica are largely from neritic depths in cold water. Cassidulina reflexa is recorded rarely, and then at neritic depths off Washington (Enbysk, 1960). A similar form, Cassidulina tortuosa Cushman and Hughes, is frequently recorded in the eastern Pacific from the Gulf of Alaska to California in neritic to lower bathyal depths (Todd and Low, 1967; Enbysk, 1960; Bandy, 1953). Natland (1957) regards this form as one of the characteristic species of his biofacies III (1.25 to 900 feet; 13° to 8.5° C.). Although detailed records of the distribution of G. auriculata are not completely clear, this general form is widespread in the seas today. Furthermore, it appears to have affinities for cold water. It is common in the arctic or cold-water regions at neritic depths, but is also found today at abyssal depths off the coast of Washington and Oregon (Enbysk, 1960). Epistominella pacifica is recorded largely from depths mostly below 600 feet, in cold water, possibly not much above 8.5° C. Temperature may be a factor in allowing this form to live in shallow depths if the water is relatively cold. Species of Uvigerina present in this section as previously discussed, also show a distinct preference for depths no less than lower neritic (600 feet). Some are most frequently found at greater depths in the bathyal and abyssal zones. Furthermore, although low-costate forms such as U. juncea and related species probably tolerate temperatures up to 13° C., others, such as the coarsely costate U. subperegrina and the hispid U. senticosa, much prefer cold water, possibly not greatly above 8.5° C.
In summary, with respect to depth of deposition, the preponderance of the evidence suggests that the frequently occurring species of the Duck Creek-Pratt Cliff section could have existed together at lower neritic, or possibly no deeper than uppermost bathyal depths, possibly at depths between 400 and 1,000 feet. Furthermore, it is significant to note an almost complete lack of forms known to be restricted to littoral and upper neritic depths, particularly representatives of Elphidium. This is a major difference between the assemblages of this section and other sections of the Quinault Formation. Indications of the probable water temperature during deposition are noticeably in favor of cool, rather than warm, conditions. Although a number of forms have tolerance for a rather wide variation in temperature, in the eastern Pacific few, if any, are restricted to warm water. Representatives of Cibicides might be the exception, as there are only a few records of C. fletcheri in the cool waters of the northeast Pacific. Recent records of a far larger number of other species of this section indicate a preference for cool to cold water, and a few are essentially confined to such conditions. Those forms somewhat indicative of relatively deep water, such as Epistominella pacifica and various representatives of Uvigerina. are essentially restricted to relatively cool conditions. Therefore, it is possible that some of these forms may have existed in somewhat more shallow conditions than normal, provided that water temperatures were cool or cold. Because of the absence of shallow-water forms restricted to relatively warm water, faunal evidence clearly indicates that water temperatures were cool to cold, possibly between 12° and 7° C., during the deposition of the Duck Creek-Pratt Cliff section of the Quinault Formation.
Redeposition of some of the sediments by turbidity currents or conventional low-speed movements no doubt did take place during the deposition of this section as is evident by the physical appearance of the sedimentary beds (Horn, 1969). However, the change of environment of the sediments probably was less severe than is evident in some of the other sections of the Quinault Formation. Probably all deposition took place in the vicinity of the outer edge of the Continental Shelf in lower neritic to upper bathyal depths.
Last Updated: 01-Jun-2006