- © 2000 by AASP Foundation
Palynomorphs record the establishment of modern conditions in the subtropical North Atlantic during the early Pleistocene. Prior to ~1.4 Ma, muds on both the New Jersey shelf and the Iberia Abyssal Plain contained relatively few terrestrial palynomorphs, and had a dinocyst flora rich in Operculodinium israelianum and other dinocyst taxa recording warmer surface waters than at present (e.g., Tectatodinium pellitum, Lingulodinium machaerophorum, and Polysphaeridium zoharyi). Over a span of ~250 ka, this palynological assemblage was succeeded by one rich in pollen and with a dinocyst flora similar to the “modern” flora, i.e. rich in Operculodinium centrocarpum, Bitectatodinium tepikiense, Spiniferites spp. (predominantly S. ramosus), and Brigantedinium spp. (predominantly B. simplex).
The synchronous palynological changes in such different geological settings in the eastern and western subtropical North Atlantic are attributed to global climatic deterioration and the expansion of ice sheets in the northern hemisphere. Climatic cooling increased the velocity of the Gulf Stream and other surface currents in the subtropical gyre, causing the gyre to contract and pull away from the continents. Glacioeustatically lowered sea levels also exposed a large percentage of the continental shelf areas, and together with other bathymetric highs like the Charleston Bump, deflected the gyre boundary currents (like the Gulf Stream) offshore. Consequently, surface waters of polar origin were able to penetrate between the warm waters of the gyre and the North American continent north of Cape Hatteras in the west, and Iberiain the east, around1.4Ma. This pale oceanographic change increased the area of “neritic” sedimentation at mid latitudes in the North Atlantic, allowing greater terrestrial influx beyond the shelfbreak.
In this study, palynological data from Quaternary sediments on the New Jersey outer shelf (ODP Leg 174A, Site 1072; Austin, Christie Blick, Malone, et al., 1998) and the Iberia Abyssal Plain (ODP Leg 149, Site 898; Whitmarsh, R.B., Sawyer, D.S., Klaus, A., D.G. et al., 1994) are examined with other published records from the subtropical North Atlantic for insights into the establishment of modern surface circulation (Text-Figure 1⇓). Chronostratigraphic control relies mainly on published nannofossil datums, but magnetostratigraphic data were also important, especially at the shelf site.
Although their biogeography and ecological requirements are less well known than those of planktonic foraminifera, dinoflagellate cysts are more reliable paleoenvironmental indicators in glacial and neritic sediments because calcareous tests tend to dissolve in cold water of less than normal marine salinity. Dinocysts, in contrast, are common in glacial and neritic sediments, particularly the “round brown” protoperidinioid cysts of the genus Brigantedinium, which are abundant in modern high latitude shelf and slope sediments (Mudie and Short, 1985; Mudie et al., 1990). The database of dinocyst distribution in the western North Atlantic has been growing rapidly in recent years (Wall et al., 1977; Harland, 1983; Mudie, 1992; de Vernal et al., 1992; Dale, 1996; Rochon et al., 1999), and relationships between dinocyst assemblages and surface water conditions have also been investigated, both qualitatively and quantitatively using multivariate statistical analysis (Edwards et al., 1991). Some general distributional patterns have been identified although taphonomic factors must be taken into account when interpreting palynological data (Zonneveld et al., 1997; McCarthy et al., submitted). Dinocysts common in temperate to equatorial environments include Operculodinium israelianum, Tectatodinium pellitum, Lingulodinium machaerophorum, Polysphaeridiumzoharyi, Tuberculodinium vancampoae, Impagidinium aculeatum, Impagidinium patulum, and Impagidinium strialatum. Dinocysts more common in subpolar to polar environments include Brigantedinium spp.,(primarily Brigantedinium simplex), Operculodinium centrocarpum, Bitectatodinium tepikiense, Nematosphaeropsis labyrinthus, Impagidinium sphaericum, and most species of Spiniferites (Wall et al., 1977; Mudie, 1992; Dale, 1996).
Prevailing winds produce an anticyclonic gyre in the subtropical North Atlantic with a strong western boundary current, the Gulf Stream, which transports equatorial water along the eastern North American continental slope to Cape Hatteras, where it is deflected across the Atlantic. The return current in the eastern North Atlantic, which forms the Canaries Current, is slightly cooler, having lost heat at higher latitudes. The central water mass in the North Atlantic subtropical gyre is the Sargasso Sea, a warm (25–28°C) and saline (~36.9 ‰) water mass (Pickard and Emery, 1982). Despite low biological productivity, sedimentation in the subtropical gyre is dominated by biogenic CaCO3 secreted by plankton. It is characterized by low terrigenous influx and sparse Pinus-dominated pollen assemblages (Mudie and McCarthy, 1994), and generally sparse dinocyst assemblages strongly dominated by gonyaulacoid cysts.
Cooler, less saline, and more variable conditions are found in neritic environments than within the open ocean. The narrow triangular region between the Gulf Stream and the continental slope north of Cape Hatteras, for instance, is occupied by a cyclonic recirculation gyre called the Slope Water, which rarely exceeds a temperature of 23°C and salinity of 36 ‰ (Milliman and Wright, 1987). According to Csanady and Hamilton (1988), some of the key features of circulation in the Slope Water are inflow of cold, relatively low salinity Coastal Labrador Sea Water across the Grand Banks, advection of warm, saline water from the Gulf Stream thermocline, and a closed cyclonic gyre in the western Slope Water, transporting ~ 3 x 106 m3/s along the New Jersey coast southward.
Terrestrial palynomorphs (pollen grains and plant spores) are much more abundant in neritic sediments than in oceanic sediments. The ratio of terrestrial to marine palynomorphs (pollen + spores: dinocysts, P:D) generally decreases offshore, except in taphonomically altered (McCarthy et al., submitted) and mass-wasted sediments (McCarthy and Mudie, 1998). High percentages of Brigantedinium spp., Operculodinium centrocarpum, Bitectatodinium tepikiense and Spiniferites spp., are found in modern sediments on the New Jersey margin (McCarthy, 1992; McCarthy and Gostlin, 2000), adinocyst assemblage similar to the “slope ecofacies” of Edwards (1991) and temperate shelf facies of Mudie (1992). A similar dinocyst flora, dominated by Bitectatodinium tepikiense, Spiniferites spp., and Operculodinium centrocarpum, was found in surface sediments from ODP Sites 898 and 900 (McCarthy and Mudie, 1996). Although protoperidinioid dinoflagellates are relatively more abundant in cooler, lower salinity or upwelling environments (Edwards et al., 1991; Mudie, 1992), the observed increase in the ratio of gonyaulacoid: protoperidinioid dinocysts (G:P) offshore (Harland, 1983; McCarthy et al., submitted) may also partly be due to taphonomic factors. For example, Zonneveld et al. (1997) found that protoperidinioid cysts are more susceptible to oxidation in environments characterized by low rates of sediment accumulation, such as most pelagic oozes (1–2 cm/ ka). The very low percentages of Brigantedinium spp. in surface sediments at the Iberia margin sites may, therefore, reflect the deeper water and low sedimentation rates (and thus greater oxidation and taphonomic alteration) on the Iberia continental rise and nearby abyssal plain over the late Pleistocene. We will show data recording the establishment of modern palynological assemblages off Iberia and New Jersey during the early Pleistocene, and we will suggest a paleoceanographic model to explain our observations.
Samples were processed using standard techniques for Quaternary marine palynology (McCarthy, 1992), including disaggregation with dilute Calgon, sieving with 150 and 10 μm mesh-size, and use of hot (~80°C) hydrochloric and hydrofluoric acid to remove carbonates and silicates, respectively. Residues were mounted in glycerine jelly, and a minimum of 200 palynomorphs (marine + terrestrial) was identified using a Leitz Ortholux microscope at x400 magnification; of that sum, a minimum of 50 of the less abundant (usually marine) palynomorph group was counted. Absolute palynomorph concentrations were estimated by the exotic spore method of Stockmarr (1971). Palynological zones were determined based on stratigraphically constrained cluster analysis using CONISS (Grimm, 1987). This multivariate statistical technique measures the degree of dissimilarity between each sample and those stratigraphically adjacent, calculated as the total sum of squares generated from a dissimilarity matrix of squared Euclidian distances (Birks and Gordon, 1985). The cluster analysis and relative abundance curves for selected taxa were plotted using CANPLOT (Campbell and McAndrews, 1992). Micrographs of several key taxa identified in this study are shown in Plates 1⇓ and 2⇓. Note that cysts identified as Operculodinium centrocarpum are Operculodinium centrocarpum sensu Wall and Dale 1966, and not the large distinctive forms comparable to the Miocene holotype of that species (Matsuoka et al., 1997).
ODP Hole 1072A
ODP Site 1072 is on the outer New Jersey Shelf. Hole 1072A was drilled at 39° 21.937′N, 72° 41.750′W, at a water depth of 98.1 m. Lithological Unit I, which spans the upper 152.13 m of Hole 1072A, was assigned a late Pliocene to Pleistocene age, and unconformably overlies Lithological Unit II, assigned a late Miocene to early Pleistocene age (Shipboard Scientific Party, 1998a). Using constrained cluster analysis, McCarthy and Gostlin (2000) identified three palynomorph zones, labeled P1 (0–90 mbsf), P2 (90–127 mbsf), and P3 (127–150 mbsf) in Hole 1072A (Text-Figure 2⇑). Palynomorph zone boundaries do not coincide with sequence boundaries (labeled pp3(s) and pp4(s) in Text-Figure 3⇑), and thus appear to be independent of sedimentological/ stratigraphic control.
Common dinocysts in palynomorph zone P1 are Brigantedinium spp., Spiniferites spp., Operculodinium centrocarpum and Bitectatodinium tepikiense, although O. centrocarpum is only common in the upper 70 m (Text-Figure 3⇑). Pollen assemblages in zone P1 are strongly dominated by gymnosperm pollen, especially Pinus, but most samples are also relatively rich in Picea (McCarthy and Gostlin, 2000). Average P:D ratios in zone P1 are fairly high and G:P values are generally low.
Both Operculodinium centrocarpum and Operculodinium israelianum are abundant in zone P2. Brigantedinium spp. and other protoperidinioid dinocysts remain common to abundant, so that G:P values remain quite low, and P:D ratios are moderate. Palynomorph Zone P2 also differs from Zone P1 in having lower relative abundances of Picea, and higher abundances of angiosperm pollen, mainly Quercus and Carya (McCarthy and Gostlin, 2000). Lingulodinium machaerophorum is most common in sparse assemblages at the erosional boundary between zones P1 and P2, possibly due to taphonomic factors.
Most of palynomorph zone P3 is characterized by high G:P and low P:D values. Spiniferites spp. and Operculodinium israelianum dominate zone P3. Other cysts not common later in the Pleistocene off New Jersey, e.g., Habibacysta tectata, Tectatodinium pellitum, Polysphaeridiumzoharyi, and Selenopemphix brevispinosa, are commonly present in zone P3 (McCarthy and Gostlin, 2000). A striking characteristic of zone P3 is the higher concentration of palynomorphs, especially gonyaulacoid cysts (Text-Figure 2⇑). A diverse angiosperm pollen flora characterises this zone, together with Pinus (McCarthy and Gostlin, 2000).
ODP Hole 898A
ODP Site 898 is in the eastern part of the Iberia Abyssal Plain. Hole 898A was drilled at 41° 41.10′N, 12° 7.38′W, at a water depth of 5279.0 m. Lithologic Unit I was assigned a late Pliocene through Pleistocene age and is separated by a major unconformity from Unit II, which was assigned an age of late Oligocene to Miocene (Shipboard Scientific Party, 1994a). Liu et al. (1996) placed the Plio–Pleistocene boundary around 144 mbsf.
Both marine and terrestrial palynomorphs in sediments below ~129 mbsf show a high degree of stratigraphic similarity, and are assigned to palynomorph zone P3 (Text-Figure 4⇑). The cluster analysis identifies the dinocyst assemblage in the sample at 121 m as anomalous, but groups it with the samples below, whereas it links the sample with those above based on the pollen data, suggesting that it is transitional between palynomorph zone P3 and the overlying zone P2. As in Hole 1072A, Operculodinium israelianum is abundant in palynomorph zone P3, while Brigantedinium spp. and Bitectatodinium tepikiense are bothrare(Text-Figure5⇑). Lingulodinium machaerophorum is common to abundant over this interval in the eastern North Atlantic, whereas it was rare in zone P3 on the New Jersey shelf, where Spiniferites spp. are relatively more abundant. Like in Hole 1072A, total palynomorph concentrations in this zone are high, and gonyaulacoid dinocysts generally dominate the assemblage, resulting in moderate to high G:P values, especially in the lower part of this zone. Pollen concentrations are relatively low, resulting in low P:D values, and angiosperm pollen is relatively abundant and diverse compared with assemblages further upcore, also similar to this zone on the New Jersey shelf.
Between ~121 and 94 mbsf, Bitectatodinium tepikiense and Brigantedinium spp. are generally abundant and both Operculodinium centrocarpum and Operculodinium israelianum are common. This assemblage is similar to palynomorph zone P2 in Hole 1072A, except for the greater abundance of B. tepikiense and L. machaerophorum in the eastern North Atlantic. The pollen data in the upper 121 m are quite homogeneous (maximum total sum of squares ~2), and strongly dominated by Pinus and other bisaccate taxa. Most samples in this zone are characterized by low G:P and high P:D values.
The most common dinocysts in the upper ~94 m of Lithological Unit I are Bitectatodinium tepikiense and Spiniferites spp. (primarily S. ramosus and S. mirabilis). Operculodinium centrocarpum and Lingulodinium machaerophorum are relatively abundant in the upper 65 m. Brigantedinium spp. are common to abundant in many samples over this interval, especially in samples with high P:D values. This assemblage is similar to zone P1 in Hole 1072A, except for the low abundances of Brigantedinium spp. in samples with low terrigenous content (i.e. low P:D values) and very high G:P values in the upper 40 m.
The “modern” (later Quaternary) dinocyst flora, rich in Brigantedinium spp., Operculodinium centrocarpum, Bitectatodinium tepikiense and Spiniferites spp., was established almost simultaneously during the early Pleistocene Matuyama magnetochron on the New Jersey and Iberia margins, replacing one with higher abundances of tropical–subtropical dinocyst taxa (such as Operculodinium israelianum, Tectatodinium pellitum and Polysphaeridium zoharyi).
The transition from palynomorph zone P3 to P2 in Hole 898A (Text-Figure 5⇑) occurs near the base of Nannofossil Zone NN19c of Rio et al. (1990), characterized by the first occurrence of the nannofossil Gephyrocapsa carribeanica >5.5 μm (1.36 Ma) (Liu et al., 1996). A similar palynological transition in Hole 604A was dated around 1.4 Ma based on nannofossil biostratigraphic data (McCarthy, 1992). The age of this palynological transition in Hole 1072A is bracketed by magnetostratigraphic data (between the Olduvai and Jaramillo Normal events, 1.77–1.07 Ma) and nannofossil data (Zone CN13b) indicating an age between 1.7 and 0.9 Ma (Text-Figure 3⇑). Because palynomorph zone P3 persists until between 1.6 and 1.3Ma in nannofossil-rich sediments in nearby Hole 1073A (McCarthy and Gostlin, 2000) on the upper New Jersey slope ( 39°13.52′N, 72°16.55′W; 639.4 m water depth; Shipboard Scientific Party, 1998b), we estimate the age of the transition from zone P3 to P2 on the New Jersey slope around 1.4 Ma as well. A similar palynological change was reported by McCarthy and Mudie (1996) in lower Pleistocene sediments in ODP Hole 900A on the Iberia rise (41°40.994′ N, 11°36.252′ W; 5036.8 m water depth; (Shipboard Scientific Party, 1994b). De Verteuil (1996) also found that tropical–subtropical dinocysts such as Operculodinium israelianum and Polysphaeridium zoharyi were relatively abundant in sediments deposited before 1.57 Ma in ODP Hole 905A on the New Jersey rise (38°36.828′ N, 72°17.024′ W; 2697.9 m water depth); (Shipboard Scientific Party, 1994c).
The transition from palynomorph zone P2 to P1 occurs near the boundary of Zones NN19d and NN19c in Hole 898A, marked by the last occurrence of Gephyrocapsa carribeanica >5.5 μm in sample 149-898A-11H-1, 105–106 cm (Liu et al., 1996). This provides an estimate of ~1.15 Ma for the establishment of the “modern” palynological assemblage. McCarthy and Gostlin (2000) estimated an age of 1.1 Ma for the transition from zone P2 to P1 on the New Jersey shelf based on the increase in abundance of spruce pollen (Picea) at the expense of angiosperm pollen, mainly Quercus and Carya. Unfortunately, sediments of this age were not recovered at ODP Sites 905 or 1073, while at Site 604 this transition is masked by extensive reworking over this interval, and at Site 900 sedimentation rates were too low to allow sufficient resolution to identify this palynolgical change.
Some of the observed palynological changes appear to be taphonomic in origin. The very high G:P values in sediments with low P:D values in Hole 898A appear to reflect the low rates of sediment accumulation during times of reduced terrigenous influx (i.e. reduced turbidity current activity) onto the Iberia Abyssal Plain (McCarthy and Mudie, 1996). Protoperidinioid dinocysts, like Brigantedinium spp., are known to be more susceptible to oxidation that gonyaulacoid cysts (Zonneveld et al., 1997), and would be more likely to deteriorate during intervals of lower sediment influx to the shelf. The low pollen concentrations in these sediments (Text-Figure 4⇑) support the interpretation of low terrigenous influx, because the alternate explanation for the sharp decrease in pollen influx —i.e., a dramatic decrease in vegetation cover or the replacement of the prevailing westerlies by anticyclonic winds around a large ice cap (c.f. COHMAP, 1988) — is inconsistent with the relatively high concentrations of cool temperate to warm temperate dinocysts like Bitectatodinium tepikiense, Spiniferites spp., Operculodinium centrocarpum and Lingulodinium machaerophorum. This interpretation suggests that the sediment accumulation rates over the last ~800 ka at Site 898 were even lower than the estimate of ~0.04 m/ka of Milkert et al. (1996). This contrasts with their estimate of ~0.16 m/ka for the interval 1.37–0.81 Ma, when the palynomorphs record less oxidation. The increased terrigenous influx which resulted in higher rates of sediment accumulation and less oxidation beginning shortly after ~1.4 Ma may reflect a greater magnitude of glacioeustatic fluctuation and/or the inception of glacial erosion and thus greater siliciclastic sediment availability at mid latitudes in North America and Europe.
The palynological transitions around 1.4 and 1.15 Ma appear to record a major change in surface water conditions, however, because 1) several gonyaulacoid dinocyst taxa are involved in the transition, and 2) very similar turnover in ecological indicator species occurred synchronously at several sites in different geological settings in the subtropical North Atlantic, from the outer shelf to the abyssal plain. The dinocyst taxa which declined around 1.4 Ma were predominantly adapted to tropical–subtropical environments. These taxa were replaced by species with broad thermal tolerances, common in temperate to subpolar environments today, suggesting a cooling of surface waters. This interpretation is supported by planktonic foraminiferal assemblages which record the establishment of cooler, probably less saline waters on the New Jersey rise (McCarthy, 1992) and on the Iberia Abyssal Plain (Gostlin, 1996) at this time. By ~1.15 Ma, the tropical–subtropical dinocysts had virtually disappeared from the mid-latitude North Atlantic Ocean. Pollen assemblages from the Cape May Formation on the Atlantic Coastal Plain (Groot, 1991) and from ODP Site 1072 (McCarthy and Gostlin, 2000) and DSDP Site 604 (McCarthy, 1992) on the New Jersey margin record significantly warmer continental climates until ~1.1 Ma, which is consistent with the loss of the moderating influence of the Gulf Stream.
At present, Coastal Labrador Sea Water flows south along the eastern Canadian margin and across the Grand Banks and allong the continental margin to Cape Hatteras, where it is forced to recirculate because the Gulf Stream flows right along the continental margin to this point. The dominantly terrigenous sediments deposited on the New Jersey margin over the last ~1.4 Ma reflect the inflow of relatively cool and low salinity Coastal Labrador Sea Water along the New Jersey coast in addition to fluvial influx into the Slope Water.
The synchronous change in surface water conditions in the eastern and western North Atlantic at mid-latitudes is attributed to climate-driven changes in the subtropical gyre (Text-Figure 6⇑). Early Pleistocene cooling of the Gulf Stream (i.e., the western boundary current of the subtropical gyre) would theoretically have strengthened the current by 15 Sv, causing the subtropical gyre to contract, resulting in southward/ eastward movement of up to 3000 km off eastern North America (Nurser and Williams, 1990). The climate-driven contraction of the subtropical gyre would increase the distance between the warm, saline Central North Atlantic waters and eastern North American and western European margins. This would have removed the moderating influence of these waters from Iberia and especially from the North American margin north of Cape Hatteras, where Coastal Labrador Sea Water currently penetrates, forming the Slope Water.
The warm water conditions recorded by the dinocysts at Sites 604, 905, 1072 and 1073 prior to ~1.4 Ma suggest that the Gulf Stream continued to flow along the continental margin north of Cape Hatteras until cooling caused separation from the margin. Kaneps (1979) also found geological evidence for an increase in the velocity of the Gulf Stream ~1.5 Ma, and a change in the path of the Gulf Stream is consistent with the interpretation of breaching of the Hatteras/Gulf Stream Outer Ridge connection by the Western Boundary Undercurrent around this time (Tucholke and Laine, 1982). The glacioeustatic lowstand would also have increased deflection of the Gulf Stream by exposing a large percentage of the eastern U.S. shelf and bathymetric highs like the Charleston Bump (Pinet et al., 1981; Pinet and Popenoe, 1985). Ujiie and Ujiie (1999) report evidence for a similar eastward deflection of the Kuroshio Current off Japan during glacioeustatic lowstands.
Because the increased current velocity caused the entire subtropical gyre to contract, it pulled away from the Iberia margin as well, allowing cool waters to penetrate between Iberia and the warm waters of the central North Atlantic. The presence of cool waters on the New Jersey and Iberia coasts would have allowed climatic deterioration to intensify, further increasing the velocity of the Gulf Stream, and causing the gyre to tighten more. Palynomorphs record the establishment of “modern” surface water conditions by around 1.15 Ma, around the time when modern bottom water conditions were established off Iberia (Collins et al., 1996) and New Jersey (Scott et al., 1998).
Palynomorphs record the synchronous establishment of “modern” surface water conditions off New Jersey and Iberia in two steps during the early Pleistocene. Pollen-rich sediments with a “modern” dinocyst flora, rich in Operculodinium centrocarpum, Bitectatodinium tepikiense, Spiniferites spp. (predominantly S. ramosus), and Brigantedinium spp. (palynomorph zone P1) record the existence of modern surface water conditions in the eastern and western mid-latitude North Atlantic over the past ~1.15 Ma. Benthic foraminiferal data also record the existence of modern bottom water conditions since that time (Collins et al., 1996; Scott et al., 1998). Prior to ~1.4 Ma, sediments containing relatively few terrestrial palynomorphs and a dinocyst flora rich in Operculodinium israelianum and other dinocyst taxa recording relatively warm surface waters accumulated in the eastern and western subtropical North Atlantic (palynomorph zone P3). A transitional zone (palynomorph zone P2) characterized the intervening ~250 ka. The establishment of cooler, probably less saline waters off New Jersey rise and Iberia is also recorded by planktonicforaminiferalassemblagesaround1.4Ma(McCarthy, 1992; Gostlin, 1996).
We attribute the synchronous change in surface water conditions in the eastern and western North Atlantic at mid-latitudes to climate-driven intensification of the subtropical gyre velocity, causing the waters of the central North Atlantic to pull away from the Iberia margin and the North American margin north of Cape Hatteras, beginning around1.4 Ma. The Gulf Stream and the Kuroshio Current (the western boundary currents of the Atlantic and Pacific subtropical gyres) are known to have been deflected eastward in response to glacioeustatic lowering and cooling, which caused the gyre current velocity to increase. Water of polar origin was then able to penetrate further south along the margins off Iberia and New Jersey, increasing the area of “neritic” sedimentation at mid latitudes in the North Atlantic, and allowing greater terrestrial influx beyond the shelfbreak. The displacement of warmer continental climates recorded by pollen in the northeastern U.S. after ~1.1 Ma is consistent with the loss of the moderating influence of the Gulf Stream by this time, and the establishment of modern oceanographic conditions.
We thank M.J. Mittelholtz, C. Younger, S. Douglas, B. Sunderland, and M. Gauthier for technical assistance, and M. Lozon for invaluable assistance with drafting. The comments of O. Davis, J. Wrenn, J.A. Austin, and an anonymous reviewer were helpful in producing the final draft of this manuscript. This work was supported by NSERC research grants and Canada ODP funds to F. McCarthy and to D. Scott, and GSC funding of Project 920063 to P. Mudie.