Sand Colour of Owen Anchorage Beaches

Home , Carnac Island, Gage Roads, West Australian (horse)

Investigation into the occurrence of grey sands: the cause, extent and origin

November 2011

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Sand Colour of Owen Anchorage Beaches

Investigation into the occurrence of grey sands: the cause, extent and origin

Prepared for

Cockburn Sound Management Council

Prepared by

Oceanica Consulting Pty Ltd

and

The University of Western Australia

November 2011

Report No. 734_001/1

Client: Cockburn Sound Management Council

Revisions history

DISTRIBUTION REVIEW Version Author No. Copies & Recipients Date Reviewer Date Format M. Carey Rev A B. Hegge 1 x Word 22/02/10 B. Hegge 23/02/10 D. Haig Rev B M. Carey B. Hegge 1 x Word 24/02/10 B. Hegge 24/02/10 Rev B M. Carey T. Rose 1 x PDF 24/02/10 Rev C P. Larcombe B. Hegge 1 X Word 13/03/11 B. Hegge 21/06/11 T. Rose 1 x PDF Rev 0 P. Larcombe 09/08/11 Oceanica 2 x Hardcopy Rev 1 K. Cox B. Hegge 1 x docm 03/11/11 B. Hegge 04/11/11 T. Rose 1 x PDF Rev 2 K. Cox 08/11/11 Oceanica 2 x Hardcopy Rev 3 K. Cox G. Botting 1 x PDF 31/05/12

Status This report is “Draft” until the author and director have signed it off for final release. A “Draft” report should not be used for any purpose other than to be reviewed with the intention of generating a “Final” version.

Approved for final release:

Author Director

Disclaimer This report has been prepared on behalf of and for the exclusive use of Cockburn Sound Management Council, and is subject to and issued in accordance with the agreed terms and scope between Cockburn Sound Management Council, Oceanica Consulting Pty Ltd and the University of Western Australia. Oceanica Consulting Pty Ltd and the University of Western Australia accepts no liability or responsibility whatsoever for it in respect of any use of or reliance upon this report by any third party.

Copying this report without the permission of Cockburn Sound Management Council, the University of Western Australia or Oceanica Consulting Pty Ltd is not permitted.

Cover

Main image: View north to Catherine Point groyne (Oceanica Consulting) Minor images: Inspecting a limestone core at Carnac Island (Oceanica Consulting); Sediment samples from north of Catherine Point groyne (Oceanica Consulting).

The Oceanica logo is a registered trade mark of Oceanica Consulting Pty Ltd which is protected by law. You may not use this trade mark without first obtaining the permission of Oceanica Consulting Pty Ltd.

Contents

Executive Summary ...... v

1. Introduction ...... 1 1.1. Background ...... 1 1.2. Key objectives ...... 2 1.3. Report structure ...... 2 1.4. Study area ...... 2

2. Environmental Setting ...... 4 2.1. Geology ...... 4 2.2. History of human use ...... 5 2.2.1. Coastal structures ...... 5 2.2.2. Nourishment...... 5 2.2.3. Dredging ...... 5 2.2.4. Landward sediment supply ...... 5 2.3. Local sediment transport patterns ...... 7

3. Field Sampling Programme ...... 8 3.1. Onshore sampling ...... 8 3.1.1. Contaminants ...... 8 3.1.2. Surface sediment characterisation ...... 9 3.1.3. Beach sediment profiles ...... 11 3.2. Offshore sampling ...... 14 3.2.1. Surface grabs ...... 14 3.2.2. Limestone cores ...... 15

4. Cause of the Grey Coloured Sands ...... 16 4.1. Contaminants ...... 16 4.1.1. Metals ...... 16 4.1.2. Polyaromatic hydrocarbons ...... 17 4.1.3. Organic hydrocarbons ...... 18 4.1.4. Petroleum hydrocarbons ...... 18 4.1.5. Pesticides ...... 18 4.1.6. Summary ...... 20 4.2. Petrography ...... 21 4.2.1. Sediment colour ...... 21 4.2.2. Sediment composition ...... 24 4.2.3. Sediment colour and composition at other locations ...... 26 4.2.4. Sediment grain size ...... 27 4.2.5. Mineralisation ...... 27 4.2.6. Summary ...... 31

5. Source and Spatial Extent of the Grey Sands ...... 32 5.1. Distribution pattern ...... 32 5.2. Source of limestone grains ...... 32 5.2.1. Possible sites of mineralisation ...... 34 5.2.2. Timing of mineralisation ...... 34

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands i 6. Changes Over Time ...... 35 6.1. Previous studies ...... 35 6.2. Vertical sediment profiles ...... 38

7. Conclusions ...... 42 7.1. Report summary...... 42 7.2. Management strategy ...... 43

8. Acknowledgements ...... 44

9. References...... 45

ii Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

List of Tables

Table 4.1 Metal concentrations in surface sediment samples (mg/kg) ...... 16 Table 4.2 Polyaromatic hydrocarbon concentrations in surface sediment samples (mg/kg)...... 17 Table 4.3 Volatile organic hydrocarbon concentrations in surface sediment samples (mg/kg)...... 18 Table 4.4 Total petroleum hydrocarbon concentrations in surface sediment samples (mg/kg)...... 18 Table 4.5 Organochlorine pesticide concentrations in surface samples from selected sites in Owen Anchorage (mg/kg) ...... 19 Table 4.6 Organophosphate pesticide concentrations in surface samples from selected sites in Owen Anchorage (mg/kg) ...... 20 Table 4.7 Dry and wet colour of sand from sites O1–O14 on Owen Anchorage beaches ...... 22 Table 4.8 Composition of sand at Owen Anchorage beaches ...... 25 Table 4.9 Composition of sand at Cottesloe, Kwinana and Becher Point beaches ...... 26 Table 4.10 Average grain size based on visual estimation against a standard grain- size chart ...... 28 Table 6.1 Summary of studies on the sedimentology and stratigraphy of Holocene sand deposits in Owen Anchorage ...... 36 Table 6.2 Description of colour variation shown at selected sediment profile sites ...... 40 Table 7.1 Cause and extent of the grey sands in Owen Anchorage ...... 43

List of Figures

Figure 1.1 Study area for grey sands investigation ...... 3 Figure 2.1 Bathymetry of Cockburn Sound and Owen Anchorage ...... 4 Figure 2.2 Coastal structures, dredging and nourishment activities within Owen Anchorage ...... 6 Figure 2.3 Net sediment transport pathways in Owen Anchorage ...... 7 Figure 3.1 Sediment sampling sites ...... 10 Figure 3.2 Example sample distribution showing mid-swash (O1A), base of dune (O1B) and crest of dune (O1C) samples from Site O1 at South Beach ...... 11 Figure 3.3 Beach sediment profile sites at Becher Point and Jervoise Bay Yacht Club ..... 12 Figure 3.4 Beach sediment profile sites at Coogee Beach, Catherine Point and South Beach ...... 13 Figure 3.5 Auger being used to 'core' a sediment profile (left); and sediment profile being exposed via digging on a dune face (right) ...... 14 Figure 3.6 Offshore surface grab sample and limestone core sampling sites ...... 14 Figure 3.7 Limestone core sampling site (left); and extracted limestone core (right) ..... 15 Figure 4.1 Variation in individual grain colours within samples O4B (left) and O11B (right) ...... 21 Figure 4.2 Representative sand samples (wet and dry) from sites O1–O14 on Owen Anchorage beaches ...... 23 Figure 4.3 Sediment colour and composition at Kwinana (left) and Becher Point (right) ...... 26 Figure 4.4 Thin sections of carbonate grains viewed in reflected light ...... 29 Figure 4.5 Microstructure of micro-granular carbonate grain which has dark mineral inclusions...... 30

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands iii Figure 5.1 Distribution of grey sands along Owen Anchorage beaches ...... 33 Figure 6.1 Sediment core from beach between Woodman Point and WAPET groynes ...... 39

List of Appendices

Appendix A Coastal structures, dredging and beach nourishment within Owen Anchorage Appendix B Contaminant Laboratory Reports Appendix C Sand Description (Surface Samples)

iv Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Executive Summary

The Cockburn Sound Management Council has been aware for some time of the community’s concern that the beaches of Owen Anchorage (particularly Coogee Beach and South Beach) are ‘turning grey’ or are darker in colour than other Perth metropolitan beaches. Noting these concerns, the CSMC committed itself to investigate this issue. The main aim of the present investigation was to identify the cause of the grey sands within Owen Anchorage.

Grey sands are not a new phenomenon for the Owen Anchorage area, with previous descriptions noting the grey colour of offshore sediments, and the consistency of this grey colour through the sediment layers of the two offshore sandbanks, Success and Parmelia Bank. A preliminary study in 2004 confirmed the presence of darker sediments on the beaches within Owen Anchorage - a feature that does not generally occur at beaches north of the Swan River, or immediately south within Cockburn Sound. However, sands further south at Becher Point (Warnbro Sound) were also found to be relatively dark in colour.

A number of sampling programmes were undertaken including onshore surface and beach sediment profile samples, offshore surface samples and limestone core samples. The analysis programme included an assessment of contaminants, and sediment colour, composition, grain size, and internal structure.

A summary of the outcomes of this study are presented in the following table.

Issue Summary  Beach sands are not contaminated.  Sands on the beaches of Owen Anchorage are made up of particles of a variety of colours.  The grey colour of some limestone particles is due to a natural process of iron sulphide precipitation within the internal structure of the sediment grains, under anoxic conditions.  The staining of these limestone grains occurs across the banks during the onshore transport of the Cause of the grey coloured sands sediments to the mainland.  The proportion of limestone particles with this iron sulphide staining greatly influences the overall colour of the beach sands (having approximately 30% of these grains will give the beach an overall dark grey colour).  Beach sands can look darker when wet due to the carbonate becoming transparent, and consequently making the dark iron sulphide more apparent.  Grey sands are present throughout Owen Anchorage beaches and primary dunes.  Grey sands are also present in other Perth metropolitan locations including Becher Point, Tern Island and Southern Flats. Source and spatial extent of the grey sands  Main source of limestone grains to the Owen Anchorage shoreline is the Garden Island Rottnest Dune Ridge system.  These limestone grains are transported eastwards across Parmelia and Success Bank to the shoreline at Woodman Point and Catherine Point respectively.  Studies dating back to the 1960's refer to grey sands being present in the Owen Anchorage area.  Sands within the offshore banks are grey throughout the full depth of their sediment profile (~15 m below Temporal extent of the grey sands seabed), representing up to ~7,000 years.  Sediment cores at Woodman Point indicate that accumulation of grey sands at the beach has occurred throughout the last 30 years.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands v The sampling, analysis and literature reviews provided in this report provide new information on the following three key issues:

1. The cause of the grey coloured sands; 2. The source and spatial extent of the grey sands; and 3. The changes over time in the presence of grey sands.

Importantly, it has been identified that the grey colouration of the sands in Owen Anchorage is due to a natural phenomenon and not a result of contamination or any industrial use of the Owen Anchorage area. Limestone, one of the three grain types found on the beaches, can have a micro-granular internal structure - and it is within the very small internal structures of individual sand grains that iron sulphide (a dark mineral) can be precipitated under anoxic conditions. These dark patches within the internal structure of the grain give the grain a grey colour, and following transport and accumulation at the beach, it is these individual grains that result in the beaches of Owen Anchorage having an overall grey colour.

The presence of sand banks or tombolos appears to be a key feature in the grey sands phenomenon. It is likely that these banks provide the opportunity for the limestone particles to be exposed to periods of anoxic conditions (in the presence of high organic matter content possibly derived from seagrasses and/or algae) during their transport onshore.

It is also considered likely that there will be some natural variation in the proportion of grey limestone particles transported to the coast each year. This variation would be associated with a number of factors including storminess, the presence of wrack (i.e. changes in the organic matter content) and sediment turnover (i.e. the amount of time the limestone particles would be exposed to reducing conditions). As shown in this study, small changes in the proportion of grey particles can have a significant effect on overall sand colour.

Therefore, it appears that the grey sands of the beaches of Owen Anchorage are due to a combination of the following factors:

1. Erosion of the Tamala Limestone from the Garden Island–Rottnest Dune Ridge System to release micro-granular (as well as other) carbonate grains. 2. Transport of these grains eastward across Parmelia and Success banks under the influence of the dominant ocean swell and seasonal storm events. 3. Exposure of these grains to reducing conditions across the sediment banks, so that iron sulphide mineralisation occurs within the grains. 4. Eventual transport of the dark limestone grains to the mainland shore and then to beaches along the southern and northern shorelines of Owen Anchorage.

A key question is whether human activities are enhancing ‘greyness’ of some beach sediments as was suggested in a report prepared by Steedman (1977). In an ideal case (where the various sediment’s sources, pathways and deposition zones are well documented and the rates of transport are known over periods of decades or more) it might be possible to distinguish the ‘signal’, generated by human activities, from the ‘noise’ of the natural variations. This signal could then be quantified, allowing construction of a notional ‘hierarchy of causation’. Unfortunately, this detailed information does not exist for Owen Anchorage. However, it is known that the changes along the shoreline are dominated by human-induced change. Indeed, the available evidence indicates that natural factors and historical human

1 The modern presence of the north-south orientated shipping channel has effectively isolated the western portion of these banks from the shoreline.

vi Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

activities at the coastline probably cause coastal change perhaps four times greater than that associated with other human activities in the area (Oceanica 2009). As a result, because of the potential causes of the greyness of the beaches, it is likely that variations in the greyness of beach sediments in the area are similarly influenced.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands vii

1. Introduction

1.1. Background The Cockburn Sound Management Council (CSMC) has been aware for some time of the community’s concern that the beaches of Owen Anchorage (particularly Coogee Beach and South Beach) are ‘turning grey’ or are darker in colour than other Perth metropolitan beaches. Some community members have suggested that Cockburn Cement’s (CCL) dredging operations on Parmelia and Success Banks are the cause of these ‘grey sands’. Noting these concerns, the CSMC publicly committed itself to investigate this issue. The State of Owen Anchorage study (Oceanica 2007) provided the CSMC with an overview of the issue and recommended strategies for further research and investigations. The following excerpt is taken from the grey sands section of The State of Owen Anchorage report:

‘Grey sands’ in Owen Anchorage have been identified as an issue by members of the public, with possible causes suggested to be discharge of wash water from CCL’s wash plant, and/or mobilising of fine grey sediments during dredging activities which then wash ashore.

A preliminary study by Oceanica confirmed the presence of grey sediment discolouration on beaches within Owen Anchorage. Comparatively, beaches in Gage Roads and Cockburn Sound do not appear to be so affected by these discolouration processes and are typically lighter, and more yellow-white in colour. Whilst the Owen Anchorage beaches themselves appear to be affected by this discolouration phenomenon, the dune systems remain the lighter white sands apart from a few areas such as near the South Fremantle power station, where it is possible that grey sands on the beach are added to by mobilised material from erosion of the dunes. The vertical extent of the grey sands appears to vary, with sands near the Jervoise Bay Yacht Club indicating the presence of a lens of grey material, rather than the sediments being discoloured to depth.

The key recommendations listed in The State of Owen Anchorage (Oceanica 2007) report and an earlier report on Sediment Colour of Southern Perth Beaches (Oceanica 2004) from the basis of the present investigation. There has also been a community concern that the grey sands may be caused by pollution or contamination; and this is also addressed in the present study.

There are a number of possibilities for the appearance of grey sediment grains on beaches. Darkening may be caused in-situ by chemical contamination. Theoretically at least, trace amounts of contaminants could interact with organic matter in the sediments to darken the sediment. Darkening may also occur by changing the type of sediments present at the shoreline. This may occur by reworking of natural sediments in the coastal zone which may either expose darker sediments and/or transport such sediments to the beach. Natural sediments may appear darker because of:

 Changes in grain size of sediments.  Changes in sediment type (i.e. composition).

It is noted that the above possibilities are not mutually exclusive and could be associated with natural and/or human factors.

Prior to The State of Owen Anchorage (Oceanica 2007) and the Sediment Colour of Southern Perth Beaches (Oceanica 2004) reports, a report prepared by Steedman & Associates was commissioned by CCL in 1977 in response to beach colouration (Steedman 1977), which at the time of the study only extended less than one kilometre east and west of CCL’s reclaimer jetty at Woodman Point. This report suggested that CCL’s operations in the area were likely the main cause of the grey sand accumulation in this region. The main findings from this study are summarised in Section 6.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 1 1.2. Key objectives The main aim of the present investigation is to identify the cause/s of the grey sands within Owen Anchorage. Key tasks identified for this study included:

 Undertake a review of available information and provide a summary of investigations and findings to date;  Undertake field investigations, sampling and analysis;  Report on the investigations and findings; and  If appropriate, provide management actions/recommendations. 1.3. Report structure This report has been structured to specifically address the following key questions asked in the study:

1. Cause of the grey coloured sands; 2. Source and spatial extent of the grey sands; and 3. Changes over time of the grey sands.

A synopsis of the field sampling and analysis is provided in Section 3, with the details of results from these investigations discussed in subsequent chapters responding to each of the three questions listed above. 1.4. Study area The study focuses on the beaches of Owen Anchorage - that is, from South Beach in the north through to Woodman Point in the South (Figure 1.1). However, sediments from other locations have been sampled to provide context and comparison for the Owen Anchorage samples; these include Cottesloe, Kwinana and Becher Point beaches, as well as offshore locations at Carnac Island, and Parmelia and Success Banks.

2 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Figure 1.1 Study area for grey sands investigation

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 3 2. Environmental Setting

2.1. Geology Owen Anchorage is characterised by a complex bathymetry including Pleistocene ridge and depression systems, and onshore Holocene sedimentary deposits (Figure 2.1). Owen Anchorage is located between two shore-parallel Tamala Limestone ridges (Pleistocene dune sequences) - Garden Island Ridge to the west and Spearwood Ridge to the east. A third limestone ridge, Five Fathom Bank, is located further offshore, separated from the Garden Island ridge by what is known as the Sepia Depression. The eastern boundary of Owen Anchorage is characterised by a shallow coastal shelf, approximately 2.5 km wide, with a depth of approximately 5 m - this shelf was created by wave erosion of the Spearwood Ridge (DCE 1979, Hearn 1991).

During the Holocene (<10,000 years before present), sediment accumulated in discrete banks in zones of wave energy convergence landward of reefs and islands of the Garden Island Ridge. The two banks within Owen Anchorage, Success and Parmelia Banks, have largely resulted from the deposition of sediment, eroded from the Rottnest Shelf and Garden Island Ridge, in the lee of reefs and islands and have formed as incipient tombolos. Success Bank formed in the lee of Mewstone Rocks and Parmelia Bank formed in the lee of Carnac Island. Once the banks had sufficiently shallowed, to within approximately 10 m from the surface, sufficient light was available for the development of extensive seagrass meadows, providing an additional source of (biogenic) sediment (DAL 1998). France (1977) distinguished three carbonate sediment units within these marine banks:

1. The lowermost unit, termed the ‘basal unit’, composed of calcareous and siliceous sands and clays; 2. The ‘core unit’, which forms the bulk of the banks, composed of limestone fragments and quartz sediments; and 3. The ‘sand sheet unit’ which consisted of the uppermost 1-2 m of the banks, and composed of shell and limestone-rich sediments.

All three units have been described as being light grey to grey in colour (DAL 1998).

Figure 2.1 Bathymetry of Cockburn Sound and Owen Anchorage

4 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

2.2. History of human use The shoreline of Owen Anchorage has had a variety of human uses, including fishing, camping, horse training, public recreation, abattoirs, power generation, marshalling yards, naval activities and industrial uses; all constructed in close proximity to the shoreline. Significant industrial development of the central area of Owen Anchorage began in the 1950’s (Le Page 1986). Historically, public access to the shoreline from Island Street groyne south to Coogee Beach has been restricted due to industrial and military uses. Recreational use has traditionally been focused north of Island Street groyne and in the vicinity of Coogee Jetty. Throughout this period of human usage, numerous anthropogenic changes have occurred within Owen Anchorage, including construction of coastal structures, beach nourishment and dredging (Figure 2.2, Appendix A).

2.2.1. Coastal structures At least 45 separate coastal structures have been constructed along the shoreline of Owen Anchorage, including harbours, marinas, breakwaters, groynes, training walls, jetties, revetments and seawalls; of these, 19 are now obsolete (Appendix A). The majority of the existing structures in Owen Anchorage were constructed after 1940; although there are still operational structures which were initially constructed in the early 1900’s (e.g. those associated with the proposed naval facilities at Woodman Point). The majority of coastal structures have been placed in the vicinity of South Beach, Catherine Point, South Fremantle Power Station (SFPS), Port Coogee and Woodman Point.

The emplacement of these structures in Owen Anchorage, particularly of groynes and breakwaters, has significantly altered natural coastal processes. Coastal structures have isolated Owen Anchorage from beaches north of Fremantle Harbour and from Cockburn Sound to the south. These structures typically modify longshore sediment transport pathways and result in the interruption of natural nearshore sediment cells. This interruption of longshore sediment transport can also occur on smaller scales within Owen Anchorage itself, for example associated with the recent construction of Port Coogee. Wave reflection off artificial structures can cause wave energy to focus on adjacent beaches and result in shoreline erosion.

2.2.2. Nourishment Nourishment and dune stabilisation have also been employed as shoreline change mitigation works in Owen Anchorage. While these are designed to protect shore-based infrastructure, they can modify the natural sediment supply to the coast. These types of works provide additional sand to the system and can mask long-term erosion trends from shoreline change records. At least 14 discrete beach nourishment, reclamation and dune construction/stabilisation activities have occurred along the beaches of Owen Anchorage (Appendix A).

Renourishment has occurred at least three times since the early 1960s around South Beach. Two such events (1964–1965 and 1996) sourced the sediment from dredging 100–500 m offshore of the beaches between Island Street groyne and Success Harbour. These inshore dredged areas can act as sediment sinks which rapidly refill with sediment, often sourced from the shoreline, thereby reducing the effectiveness of the renourishment works.

2.2.3. Dredging Dredging activities in Owen Anchorage include capital and maintenance dredging of shipping channels, navigation access to jetties and harbour facilities, and resource (shellsand) dredging (Appendix A). The largest dredging works in Owen Anchorage have been associated with the development of Fremantle Harbour (beginning early 1900’s), capital dredging of Success and Parmelia Channels (1914-1918), and the ongoing shellsand dredging by CCL (since 1972).

2.2.4. Landward sediment supply In Owen Anchorage it appears that an important secondary impact from dredging activity is the enhancement of landward sediment transport due to dredged material. Between approximately 1964 and 1994, significant shoreline accretion occurred near Catherine Point, and to a lesser extent, between 1976 and 1987 at Woodman Point - and it appears that this

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 5 accretion was largely sustained by the landward transport of sediment resulting from the side-cast disposal (to the eastern side of the channel) of material from navigation channel dredging through Success and Parmelia Banks in the 1940’s and 1950’s. It has been estimated2 that while active, this onshore sediment supply bought an additional 43,500 m3/yr and 16,000 m3/yr onshore to Catherine Point and Woodman Point respectively (Oceanica 2009).

Figure 2.2 Coastal structures, dredging and nourishment activities within Owen Anchorage

2These are considered first order approximations, and it is acknowledged that other factors have also affected shoreline change over this period (although assumed to be of a lesser extent).

6 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

2.3. Local sediment transport patterns In Owen Anchorage, the winter season typically results in a net southward sediment flux due to the short duration high-energy storm events; whereas in summer, northward sediment transport dominates under the influence of seas produced by the sea-breeze and swell waves forming in the Indian Ocean. Seasonal reversal of the prevailing wind and wave directions causes corresponding reversals in the direction of sediment transport and a rotation in the alignment of pocket beaches within Owen Anchorage.

The main source of sediment to the shoreline of Owen Anchorage is the landward part of Success Bank (feeding Catherine Point) and Parmelia Bank (feeding Woodman Point) (Figure 2.3). For the coast north of Catherine Point, northwards transport over summer and autumn generally exceeds the southerly reversal during winter. South of Catherine Point, the angle of the shore enhances southward transport and reduces the effect of sea breeze wind waves, resulting in a net southwards sediment transport. These basic patterns of movement have been complicated through the construction of a number of coastal structures (see Section 2.2) along the Owen Anchorage coast.

Note: 1. The size of arrows indicates the relative magnitude of sediment flux.

Figure 2.3 Net sediment transport pathways in Owen Anchorage

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 7 3. Field Sampling Programme

3.1. Onshore sampling

3.1.1. Contaminants The possibility that contamination has caused the grey colouration of the beach sands had been raised by the community to the CSMC, and, theoretically at least, trace amounts of contaminants could interact with organic matter in the sediments to darken the overall appearance of the sediments. Consequently, the first element of the field surveys was designed to include the collection of surface sediment samples to be submitted for contaminant analysis.

Sampling In May 2008, sediment samples were collected at 14 sites within Owen Anchorage plus three reference sites—one each at Cottesloe, Kwinana and Becher Point (Figure 3.1). Samples were collected from the upper swash zone. A sub-sample of sites were submitted for analysis, namely, Owen Anchorage sites O2, O3, O5, O6, O8, O10 and O13 (the remaining samples were frozen for future analysis if required). These sites were chosen as either being popular beach sites (e.g. South Beach, Coogee Beach) or being in proximity to known potential contaminant source sites (e.g. South Fremantle Power station), and a sample from near the CCL reclaimer jetty.

At each site a surface sediment sample was collected using 9.5 cm diameter polycarbonate corers (according to the procedures set out in Australian Standard AS/NZS 5667.12:1999). The corer was washed between sampling sites with site water before sampling. Each of the samples was composited from five sub-samples of the top 2 cm of sediment obtained from the four corners and the centre of a 1 m² quadrat. The rationale for this design is the need to obtain a good estimate of concentration within each site, while minimising the ‘within-site’ sampling variance to enable better trend detection (if present). This is consistent with the method outlined in the Manual of Standard Operating Procedures for Environmental Monitoring against the Cockburn Sound Environmental Quality Criteria (2003-2004) (EPA 2005a). Sediment samples were placed in pre-cleaned glass containers supplied by the analytical laboratory (as prescribed in Australian Standard AS/NZS 5667.12:1999) and kept on ice while in transit to the analytical laboratory.

Each of the sediment samples was analysed for:

 Metals - antimony (Sb), arsenic (As), cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Mercury (Hg), Nickel (Ni), Silver (Ag), Zinc (Zn); and  Total organic carbon;  Polyaromatic hydrocarbons (PAHs);  Total Petroleum Hydrocarbons (TPHs) and BTEX; and  Organochlorine and organophosphate pesticides.

Guidelines The results of theses analyses are presented in Section 4.1; and for comparative purposes each table also contains ecological and human health guideline values (where available). There are three sets of appropriate guidelines:

 The Interim Sediment Quality Guidelines Low (ISQG-Low) as per Table 3.5.1 of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ARMCANZ 2000);  The Cockburn Sound Environmental Quality Criteria (EQC) for toxicants in sediment as per Table 3 of Environmental Quality Criteria Reference Document for Cockburn Sound (2003-2004) (EPA 2005b), specifically the Environmental Quality Guidelines ‘Value’ (EQG ‘Value’); and  The Health Investigation Levels (HIL) for category E (relevant for parks, recreational open space and playing fields, includes secondary schools) as per Table 1 of the contaminated sites criteria in Assessment Levels for Soil, Sediment and Water (DoE 2003)

8 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

As the sites are located within Owen Anchorage the ISQG-Low are the most applicable guidelines. However, ISQG values have not been developed for some metals (e.g. aluminium, manganese, titanium) because they are generally considered to have low toxicity in marine sediments (as well as being a major component of most sediments), or due to the lack of toxicity data (e.g. cobalt, vanadium). Due to the proximity to Cockburn Sound, the EQC are also included for comparison, but the EQG ‘Values’ are essentially the same values as the ISQG-Lows. The contaminated sites criteria were also used for comparison as they include a consideration of health effects; however, these are shown for comparative purposes only, as Owen Anchorage is not considered a contaminated site.

3.1.2. Surface sediment characterisation In December 2009, further sediment samples were also collected at the same 14 sites within Owen Anchorage plus three reference sites—one each at Cottesloe, Kwinana and Becher Point (Figure 3.1). At each site, surface grab samples were collected from the (a) mid-swash, (b) base of the primary dune, and (c) crest of the primary dune (Figure 3.2). A secondary dune sample was also collected south of Port Coogee (Site O7). The following sediment characteristics were documented for these samples:

 Sediment colour, in both wet and dry states, was determined using the Munsell Soil Colour charts;  Sediment composition was determined via a systematic count of >300 grains on a gridded tray under a stereomicroscope using reflected light;  Visual sediment grain size analysis and an assessment of the relationship between grain size and sand colour;  Petrology analysis on one sample from each locality:  The sample was embedded in a blue-stained resin and a thin (30 µm) section was cut; the thin section was then examined in both transmitted and reflected light. The transmitted light image distinguishes the microstructure of carbonate grains, with coarsely crystalline material being transparent to light (giving a bright image), and microcrystalline/micro-granular material being opaque to light due to the internal reflection and refraction of light within the grain (therefore giving a dark image). The reflected light image shows the colour of the carbonate grains as well as the transparency to light.  The percentage of ‘dark’ grains versus ‘light’ grains in a total grain count was determined by systematically traversing the slide.  The dark grains were then further examined for evidence of mineralisation.  The percentage of carbonate grains showing dark mineralisation in a total carbonate grain count was also determined by systematically traversing the slide.  Geochemical analyses on selected samples:  Selected acid-etched grains were mounted on a metal stub using carbon tape and coated with a carbon. The grains were then examined using a Zeiss 1555 Variable Pressure Scanning Electron Microscope (VPSEM) in high-vacuum mode. The accelerating voltage of 15 kV and an Everhart-Thornley secondary electron detector were used. The occurrence of elements in a spot analysis was qualitatively determined, with a detection resolution of approximately 0.1% abundance of the element in the spot.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 9

Figure 3.1 Sediment sampling sites

10 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Figure 3.2 Example sample distribution showing mid-swash (O1A), base of dune (O1B) and crest of dune (O1C) samples from Site O1 at South Beach

3.1.3. Beach sediment profiles A number of sediment profiles were sampled within the study area, namely at Becher Point, near the Jervoise Bay Yacht Club, Coogee Beach, north of Catherine Point groyne and South Beach (Figure 3.4–Figure 3.4). The sediment profiles were either sampled using a hand-held auger to 'core' out material, or by digging into the beach/dune face to reveal the profile (Figure 3.5). Visual assessment of colour (via Munsell Soil Colour charts) and sediment size were recorded at each site.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 11

Figure 3.3 Beach sediment profile sites at Becher Point and Jervoise Bay Yacht Club

12 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Figure 3.4 Beach sediment profile sites at Coogee Beach, Catherine Point and South Beach

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 13

Figure 3.5 Auger being used to 'core' a sediment profile (left); and sediment profile being exposed via digging on a dune face (right)

3.2. Offshore sampling

3.2.1. Surface grabs A Van Veen grab sampler was used to collect surface samples from sites along Success Bank between Mewstone and the shipping channel. Two surface grabs were also collected from the beach on the eastern side of Carnac Island. These samples were visually assessed for sediment colour using the Munsell Soil Colour charts.

Figure 3.6 Offshore surface grab sample and limestone core sampling sites

14 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

3.2.2. Limestone cores In November 2008, five limestone core samples were collected from Carnac Island to examine the sediment characteristics of this offshore limestone. This was undertaken to enable a comparison of limestone characteristics with the shoreline sediments to assess the potential importance of these offshore limestones as a source of sediment to Owen Anchorage beaches. Carnac Island was chosen because the limestone outcrops on this island form part of the Rottnest Garden Island Ridge System. The limestone cores were collected using a hand-held cement core drill using a 100 mm x 500 mm drill bit (Figure 3.7). The colour and composition of the limestone cores was analysed, including a description of foraminiferal assemblages.

Figure 3.7 Limestone core sampling site (left); and extracted limestone core (right)

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 15 4. Cause of the Grey Coloured Sands

4.1. Contaminants

4.1.1. Metals Concentrations of antimony, cadmium, copper, mercury, nickel and silver at all sites were below reporting limits (Table 4.1, Appendix B). All metal concentrations were well below relevant guidelines (Table 4.1), therefore showing no indication of metal contamination.

Table 4.1 Metal concentrations in surface sediment samples (mg/kg)

Analyte

Zinc

Iron

Lead

Silver

Nickel

Copper

Arsenic

Mercury

Cadmium

Antimony

Chromium Manganese

Reporting 0.5 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.1 1.0 1.0 1.0 Limit ISQG-Low 2 20 1.5 80 65 50 0.15 21 1 200 EQG Value 2 20 1.5 80 65 50 0.15 21 1 200 HIL Group E 200 40 2,000 600 3,000 30 600 14,000 02A <0.5 1.2 <1 10.4 <1 430 1.7 10.6 <0.1 <1 <1 1.6 03A <0.5 2.1 <1 13.6 <1 640 4.8 17.3 <0.1 <1 <1 3.7 05A <0.5 1.9 <1 13.1 <1 570 3.3 15.3 <0.1 <1 <1 2.3 06A <0.5 1.6 <1 14.1 <1 590 3.0 15.3 <0.1 <1 <1 3.1 08A <0.5 1.1 <1 12.7 <1 450 2.3 12.3 <0.1 <1 <1 3.5 010A <0.5 1.8 <1 13.2 <1 520 1.8 13.1 <0.1 <1 <1 3.1 013A <0.5 2.0 <1 13.9 <1 630 1.5 18.5 <0.1 <1 <1 3.6

16 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

4.1.2. Polyaromatic hydrocarbons PAHs were analysed at ultra-low detection limits to ensure trace levels could be detected, and to ensure that reporting limit was low enough for comparison against sediment criteria. All PAH concentrations were below reporting limits, and well below relevant guidelines for all sediment samples3 (Table 4.2, Appendix B).

Table 4.2 Polyaromatic hydrocarbon concentrations in surface sediment samples (mg/kg)

cd)pyrene -

Analyte

Pyrene

Fluorene

Chrysene

Anthracene

Naphthalene

Fluoranthene

Phenanthrene

Acenaphthene

Acenaphthylene

Benzo(a)pyrene

Benz(a)anthracene

Benzo(ghi)perylene

Dibenz(ah)anthracene

Indeno(1,2,3 Benzo(b)&(k)fluoranthene

Reporting 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 Limit ISQG- 160 44 16 19 240 85 600 665 261 384 430 63 Low EQG 160 44 16 19 240 85 600 665 261 384 430 63 Value HIL 2 Group E 02A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 03A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 05A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 06A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 08A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 010A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01 013A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.01

3As all measured values were below the reporting limit, they were not normalised against total organic carbon content. However, the concentrations are sufficiently low that they would still be below available guidelines.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 17 4.1.3. Organic hydrocarbons All BTEX concentrations were below reporting limits for all sediment samples (Table 4.3, Appendix B). There are no guidelines available for the BTEX group of chemicals.

Table 4.3 Volatile organic hydrocarbon concentrations in surface sediment samples (mg/kg)

Analyte

Xylene

Toluene

Benzene

Total BTEX Total Ethylbenzene

Reporting Limit 0.5 0.5 0.5 1.0 2.5 ISQG-Low EQG Value No guideline values specified HIL Group E 02A <0.5 <0.5 <0.5 <1.0 <2.5 03A <0.5 <0.5 <0.5 <1.0 <2.5 05A <0.5 <0.5 <0.5 <1.0 <2.5 06A <0.5 <0.5 <0.5 <1.0 <2.5 08A <0.5 <0.5 <0.5 <1.0 <2.5 010A <0.5 <0.5 <0.5 <1.0 <2.5 013A <0.5 <0.5 <0.5 <1.0 <2.5

4.1.4. Petroleum hydrocarbons All TPH concentrations were below reporting limits for all sediment samples (Table 4.4, Appendix B). There are no guidelines available for the TPH group of chemicals.

Table 4.4 Total petroleum hydrocarbon concentrations in surface sediment samples (mg/kg)

9 14 28 36

C C C C

- - - -

15 29

Analyte 10

TPH C TPH TPH Total

TPH C TPH C TPH C TPH

Reporting Limit 25 50 100 100 275 ISQG-Low EQG Value No guideline values specified HIL Group E 02A <25 <50 <100 <100 <275 03A <25 <50 <100 <100 <275 05A <25 <50 <100 <100 <275 06A <25 <50 <100 <100 <275 08A <25 <50 <100 <100 <275 010A <25 <50 <100 <100 <275 013A <25 <50 <100 <100 <275

4.1.5. Pesticides Both organochlorine (OC) and organophophate (OP) pesticides were analysed at low detection limits to ensure trace levels could be detected, and to ensure that reporting limit was low enough for comparison against sediment criteria. All OC and OP pesticide concentrations were below reporting limits and well below guidelines (where available) for all sediment samples4 (Table 4.5, Table 4.6, Appendix B).

4As all measured values were below the reporting limit, they were not normalised against total organic carbon content. However, the concentrations are sufficiently low that they would still be below available guidelines.

18 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Table 4.5 Organochlorine pesticide concentrations in surface samples from selected sites in

Owen Anchorage (mg/kg)

BHC

- -

Analyte -

Chlordane

HCB

Aldrin

BHC (Lindane) BHC

Chlordane

beta

delta

alpha

Heptachlor

cis

Oxychlordane

trans

Heptachlor epoxide Heptachlor Gamma

Reporting 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 Limit ISQG-Low 0.32 EQG Value 0.32 HIL Group 20 E 02A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 03A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 05A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 06A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 08A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 010A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

013A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

DDE DDT

Analyte DDD

- -

Endosulfan

Endrin

pp pp

Dieldrin

Methoxychlor

Endrin Ketone Endrin

Endrin Aldehyde Endrin

beta

alpha Endosulfan Sulfate Endosulfan

Reporting 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 Limit ISQG-Low 0.02 2.2 2.0 1.6 0.02 EQG Value 0.02 2.2 2.0 1.6 0.02 HIL Group 400 (DDE+DDD+DDT) E 02A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 03A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 05A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 06A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 08A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 010A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 013A <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 19 Table 4.6 Organophosphate pesticide concentrations in surface samples from selected sites

in Owen Anchorage (mg/kg)

Methyl

- S

Analyte -

Ethion

Diazinon

Fenthion

Malathion

Dichlorvos

Dimethoate

Chlorpyrifos

Demeton Chlorpyrifos Methyl Chlorpyrifos

Reporting Limit 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 ISQG-Low EQG Value HIL Group E 02A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 03A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 05A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 06A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 08A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 010A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01

013A <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01

Analyte

Fenitrothion

Azinphos Ethyl Azinphos

Pirimiphos Ethyl Pirimiphos

Azinphos Methyl Azinphos

Parathion Methyl Parathion

Parathion (Ethyl) Parathion

Pirimiphos Methyl Pirimiphos

Chlorfenvinphos (E) Chlorfenvinphos Chlorfenvinphos (Z) Chlorfenvinphos

4.1.6. Summary Results of the sediment analyses show that all PAH, TPH, BTEX, OP and OC were all below reporting limits and well below guidelines values where available. Metal concentrations were also very low. Therefore, the results of the contaminant analyses indicate that the grey colour of beach sediment in Owen Anchorage is very unlikely to be due to contamination.

20 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

4.2. Petrography

4.2.1. Sediment colour The Owen Anchorage beach sand samples are composed of grains of variable colour (Figure 4.1). However, the overall dry colour of the beach sands generally varied from light grey (Munsell 2.5Y 7/1–2) to grey (Munsell 2.5Y 5/1), with a light brownish grey sand (Munsell 2.5Y 6/2) present at one locality (Table 4.7, Figure 4.2, Appendix C). The wet sand samples typically appear darker than dry sand (Table 4.7)5. At each site, there was little difference between sand colour in the swash zone, at the base or the crest of the primary dune (Table 4.7, Figure 4.2).

Note: 1. Field of view is 5 mm across.

Figure 4.1 Variation in individual grain colours within samples O4B (left) and O11B (right)

5Refer to Section 4.2.5 for discussion on this.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 21 Table 4.7 Dry and wet colour of sand from sites O1–O14 on Owen Anchorage beaches

Sample1 Dry Sand Colour2 Wet Sand Colour2

01A 2.5Y 7/2 light grey 2.5Y 7/2 light grey 01B 2.5Y 7/1 light grey 2.5Y 7/2 light grey 01C 2.5Y 7/1 light grey 2.5Y 7/3 pale yellow 02A 2.5Y 6/1 grey 2.5Y 5/1 grey 02B 2.5Y 6/1 grey 2.5Y 5/1 grey 02C 2.5Y 6/1 grey 2.5Y 5/1 grey 03A 2.5Y 6/1 grey 2.5Y 5/1 grey 03B 2.5Y 6/1 grey 2.5Y 4/1 dark grey 03C 2.5Y 6/1 grey 2.5Y 4/1 dark grey 04A 2.5Y 6/1 grey 2.5Y 5/1 grey 04B 2.5Y 6/1 grey 2.5Y 4/1 dark grey 04C 2.5Y 6/1 grey 2.5Y 4/2 dark greyish brown 05A 2.5YR 6/1 grey 2.5Y 4/1 dark grey 05B 2.5Y 5/1 grey 2.5Y 4/1 dark grey 05C 2.5Y 5/1 grey 2.5Y 4/1 dark grey 06A 2.5Y 5/1 grey 2.5Y 4/1 dark grey 06B 2.5Y 5/1 grey 2.5Y 4/1 dark grey 06C 2.5Y 5/1 grey 2.5Y 4/1 dark grey 07A 2.5YR 7/2 light grey 2.5Y 7/2 light grey 07B 2.5Y 6/1 grey 2.5Y 6/2 light brownish grey 07C 2.5Y 7/2 light grey 2.5Y 6/2 light brownish grey 07D 2.5Y 7/2 light grey 2.5Y 6/2 light brownish grey 08A 2.5Y 7/2 light grey 2.5Y 7/3 pale yellow 08B 2.5Y 7/2 light grey 2.5Y 7/3 pale yellow 08C 2.5Y 7/2 light grey 2.5Y 7/3 pale yellow 09A 2.5Y 7/2 light grey 2.5Y 7/3 pale yellow 09B 2.5Y 7/2 light grey 2.5Y 7/3 pale yellow 09C 2.5Y 7/2 light grey 2.5Y 6/2 light brownish grey 10A 2.5Y 6/2 light brownish grey 2.5Y 6/2 light brownish grey 10B 2.5Y 6/2 light brownish grey 2.5Y 6/3 light yellowish brown 10C 2.5Y 6/2 light brownish grey 2.5Y 6/3 light yellowish brown 11A 2.5Y 5/1 grey 2.5Y 5/2 greyish brown 11B 2.5Y 5/1 grey 2.5Y 5/2 greyish brown 11C 2.5Y 5/1 grey 2.5Y 5/2 greyish brown 12A 2.5Y 5/1 grey 2.5Y 5/2 greyish brown 12B 2.5Y 5/1 grey 2.5Y 4/1 dark grey 13A 2.5Y 5/1 grey 2.5Y 4/1 dark grey 13B 2.5Y 5/1 grey 2.5Y 4/1 dark grey 14A 2.5Y 5/1 grey 2.5Y 4/1 dark grey 14B 2.5Y 5/1 grey 2.5Y 4/1 dark grey 14C 2.5Y 5/1 grey 2.5Y 4/1 dark grey Note: 1. Samples are designated to position across beach as follows: A = mid-swash, B = base of primary dune, C = crest of primary dune, and D = secondary dune. 2. A conversion of Munsell colour to an approximate RGB colour code was performed using BabelColor. The colours presented above are intended to provide visual comparison between the samples and are not intended to take the place of a Munsell Soil Colour Chart. Note also that BabelColor had no colour defined for 2.5Y 6/3 and 2.5Y 7/3, and so these have been substituted with 6/4 and 7/4 respectively.

22 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

(a) Dry Sand (b) Wet Sand

Note: 1. A = mid-swash sample, B = base of primary dune, C = crest of primary dune

Figure 4.2 Representative sand samples (wet and dry) from sites O1–O14 on Owen Anchorage beaches

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 23 4.2.2. Sediment composition Sand forming the beaches along Owen Anchorage is composed of three main grain types: a) Modern biogenic (carbonate) grains; b) Older limestone (carbonate) grains; and c) Quartz.

In the grain counts, minor amounts of feldspar have been included with quartz (Table 4.8, Appendix C).

The biogenic grains are, in order of decreasing abundance: mollusc fragments, foraminiferal tests, coralline algal debris, echinoid plates, bryozoan debris, sponge spicules, ostracod carapaces, and soft coral spicules. Most of these biogenic grains are white in colour; however, exceptions include: (a) some of the mollusc shells have brown colour banding and some mytiliform bivalves have purplish fibrous shell layers; (b) some echinoid spines are orange, purple, or green; and (c) some hyaline benthic foraminifera have brown organic linings in their tests. The coloured biogenic grains form a minor component of the biogenic sediment and have no influence on the overall sand colour. For this study, different groups of biogenic grains have not been distinguished.

The limestone grains range in colour from white to black, with some also having brown or yellow tinges. Within a single grain, a spectrum of colours from white to black is also common. For the grain counts shown in Table 4.7, "white" to "pale yellow" grains (Munsell Colour 2.5Y 8/1 to 2.5Y 8/4) are classified in the pale limestone category; and "light grey" to "black" grains (Munsell Colour 2.5Y 7/1 to 2.5Y 2.5/1) are included in the dark limestone category. Many of the limestone grains are in the form of fossils eroded from the limestone, and can be distinguished from modern biogenic grains by having cavities infilled by cement and/or a micritic matrix. Some of the fossils (especially the fossil gastropods) are internal moulds from which the original external skeleton is missing (likely due to abrasion or corrosion).

The distribution of grain types and the pattern of dominant grain type as shown in Table 4.8 indicate:

 Biogenic grains are dominant in the swash-zones of beaches that front Success Bank (sites O1–O6). The northern most of these beaches (site O1) has quartz dominating the primary dune sediment. The southern beaches of this set (sites O3–O6) have limestone as the dominant grain type in the primary dune.  Biogenic grains dominate all parts of the beaches sampled at sites O7–O9, fronting the central section of Owen Anchorage.  Biogenic grains are dominant in the swash-zones of beaches (sites O10-O12) that lie on the north side of Parmelia Bank. At sites O10 and O11, limestone is the dominant grain type in the primary dune; but at site O12, biogenic grains are dominant at the base of the primary dune.  Limestone grains dominant sand in the beaches on the northern side of the Woodman Point sand spit (sites O13 and O14).

The percentage of dark limestone grains in the sand has a significant influence on the overall colour of the sand (Table 4.8). Light grey sand has from 2% to 7% dark limestone grains in the total grain count. Light brownish grey sand has from 7% to 15% dark limestone grains in the total grain count. Grey sand has up to 33 % dark limestone grains in the total grain count.

24 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Table 4.8 Composition of sand at Owen Anchorage beaches

Percent (%) Abundance2 1 Total Sample Colour (Dry) Dark Pale Biogenic Heavy Quartz Count limestone limestone grains minerals 01A 2.5Y 7/2 light grey 4 3 71 22 0 514 01B 2.5Y 7/1 light grey 7 18 18 57 0 306 01C 2.5Y 7/1 light grey 6 12 25 58 0 328 02A 2.5Y 6/1 grey 9 6 61 23 0 553 2B 2.5Y 6/1 grey 20 26 19 35 0 339 02C 2.5Y 6/1 grey 13 23 22 43 0 338 03A 2.5Y 6/1 grey 12 11 63 14 0 555 03B 2.5Y 6/1 grey 31 40 20 9 <0.1 346 03C 2.5Y 6/1 grey 24 37 21 18 0 342 04A 2.5Y 6/1 grey 13 20 57 11 0 520 04B 2.5Y 6/1 grey 26 46 15 13 0 329 04C 2.5Y 6/1 grey 32 45 11 12 0 406 05A 2.5YR 6/1 grey 11 19 62 8 0 542 05B 2.5Y 5/1 grey 33 40 15 12 0 339 05C 2.5Y 5/1 grey 31 41 15 13 0 420 06A 2.5Y 5/1 grey 13 18 51 18 0 547 06B 2.5Y 5/1 grey 23 45 21 11 0 359 06C 2.5Y 5/1 grey 21 42 22 15 0 306 07A 2.5YR 7/2 light grey 2 2 83 13 0 764 07B 2.5Y 6/1 grey 6 14 44 36 0 348 07C 2.5Y 7/2 light grey 4 8 52 36 0 397 07D 2.5Y 7/2 light grey 3 4 74 20 0 317 08A 2.5Y 7/2 light grey 3 4 73 21 0 571 08B 2.5Y 7/2 light grey 3 10 51 37 0 304 08C 2.5Y 7/2 light grey 2 8 56 33 0 428 09A 2.5Y 7/2 light grey 3 6 74 17 0 584 09B 2.5Y 7/2 light grey 6 19 53 23 0 373 09C 2.5Y 7/2 light grey 5 25 48 22 0 354 2.5Y 6/2 light 10A 7 10 68 16 0 702 brownish grey 2.5Y 6/2 light 10B 15 41 30 13 0 312 brownish grey 2.5Y 6/2 light 10C 7 36 39 18 0 531 brownish grey 11A 2.5Y 5/1 grey 11 13 69 7 0 525 11B 2.5Y 5/1 grey 16 42 36 5 0 300 11C 2.5Y 5/1 grey 18 36 39 6 0 357 12A 2.5Y 5/1 grey 16 32 50 3 0 372 12B 2.5Y 5/1 grey 15 22 60 2 0 603 13A 2.5Y 5/1 grey 21 37 40 2 0 327 13B 2.5Y 5/1 grey 23 56 18 3 0 511 14A 2.5Y 5/1 grey 18 56 25 1 0 322 14B 2.5Y 5/1 grey 15 59 22 4 0 545 14C 2.5Y 5/1 grey 14 54 31 1 0 302 Note: 1. Samples are designated to position across beach as follows: A = mid-swash, B = base of primary dune, C = crest of primary dune, and D = secondary dune. 2. Dominant grain type is highlighted in bold font. For the dominant grain type, limestone is considered as the sum of both dark and pale particles.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 25 4.2.3. Sediment colour and composition at other locations Table 4.9 shows the colour (dry sand) and grain composition of samples collected from Becher Point (B1A-C), Cottesloe Beach (C1-C), and Kwinana Beach (C2A-C).

Becher Point lies at the landward end of a tombolo which extends from the Garden Island Rottnest Dune Ridge System—this corresponds to the geological setting of the beaches with the grey sands within Owen Anchorage. The Becher Point sands are similar in colour and composition to those found on the Owen Anchorage beaches adjacent to Success and Parmelia Banks. Limestone grains are dominant in the dune samples, and the sands have an overall grey (Munsell 2.5Y 5/1) colour (Table 4.9).

Conversely, the two 'reference' sites at Kwinana and Cottesloe show quite different grain type compositions, being dominated by biogenic and quartz particles respectively (Table 4.9). The colour of these two samples, being pale yellow, was also significantly different from the Becher Point and Owen Anchorage sands (Table 4.8, Table 4.9, Figure 4.3).

Sands from the beach on the eastern side of Carnac Island were a light grey colour (Munsell 2.5Y 7/2), similar to those in central Owen Anchorage. The five Van Veen grab samples across Success Bank, between Mewstone Rock and the shipping channel, were also grey in colour (Munsell 2.5Y 5/2–6/2).

Table 4.9 Composition of sand at Cottesloe, Kwinana and Becher Point beaches

Percent (%) Abundance2 1 Total Sample Colour (Dry) Dark Pale Biogenic Heavy Quartz Count limestone limestone grains minerals C1A 2.5Y 7/3 pale yellow <0.5 10 3 87 <1 315 C1B 2.5Y 8/2 pale yellow <1 10 15 74 1 505 C1C 2.5Y 8/2 pale yellow <0.5 17 18 65 <1 205 C2A 2.5Y 7/4 pale yellow 1 2 80 18 0 537 C2B 2.5Y 7/3 pale yellow 2 18 61 19 0 247 C2C 2.5Y 7/3 pale yellow 2 10 61 28 0 378 B1A 2.5Y 5/1 grey 15 24 53 8 0 433 B1B 2.5Y 5/1 grey 22 36 35 7 0 535 B1C 2.5Y 5/1 grey 14 38 39 8 0 385 Note: 1. Samples are designated to position across beach as follows: A = mid-swash, B = base of primary dune, C = crest of primary dune, and D = secondary dune. 2. Dominant grain type is highlighted in bold font. For the dominant grain type, limestone is considered as the sum of both dark and pale particles.

Note: 1. Field of view is 1 mm across.

Figure 4.3 Sediment colour and composition at Kwinana (left) and Becher Point (right)

26 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

4.2.4. Sediment grain size The beach sands were visually assessed for grain size by comparison to a standard grain-size chart that characterises sand into the following divisions:

 very fine sand: 63–125 µm  fine sand: 125–250 µm  medium sand: 500–1,000 µm  coarse sand: 1000–2,000 µm

The beach sand samples ranged in average grain size from coarse sand (upper class) to medium sand (upper class), and are well- to moderately well sorted (Table 4.10). The coarsest sand comes from beaches adjacent to Success and Parmelia Banks; whereas the beach with the finest sand, overall, is at site O9, facing the central section of Owen Anchorage.

The coarse sand (upper class) deposits range in colour from light grey and light brownish grey to grey. The medium sand (upper class) deposits range in colour from light grey to grey. Given the overlap in colour of the sands, grain size seems not to have a significant influence on the overall sediment colour.

4.2.5. Mineralisation As noted above, the limestone particles are generally the only grain type that has a significant proportion of grains with a grey to black colour. However, it is notable that a small percentage of modern porcellaneous foraminifera (part of the biogenic sand component) also have minute black patches. These 'coloured' limestone grains were further examined via a thin section under both transmitted and reflected light. Optical analysis indicated a clear relationship between microstructure and the presence of a dark mineralisation within the grain. The two main types of microstructure present in the carbonate grains are: a) Coarsely crystalline carbonate with crystal size approximately 20 µm or larger; and b) Micro-granular carbonate with micron-size granules.

Minute (up to ~50 µm in diameter) dark mineral growths are present in the micro-granular carbonate of many grains (Figure 4.4a-e); but these growths are not present in the coarsely crystalline carbonate. The dark mineral deposits do not coat the grains, but are present in irregular patches within the structure of the grain itself. In some grains, concentrations of the dark mineral patches appear to be present in zones that parallel the grain surface. This zoning suggests that the mineralisation took place after the grain was eroded from the limestone source. The presence of dark mineral within the micro-granular structure of the modern porcellaneous foraminifera further supports this view that the dark staining has occurred in a contemporary environment. Rare grains of coralline algae show evidence of the dark mineral replacing part of the micro-granular wall of the algal cells (Figure 4.4f).

Electron microanalysis of selected acid-etched grains and polished thin sections indicates that the dark mineral is iron sulphide (Figure 4.5). The occurrence of the dark mineralisation as an internal staining within an otherwise white grain explains why the sand becomes darker when wet, because when the carbonate grains are wet they become more transparent, thereby revealing more of the dark internal minerals.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 27 Table 4.10 Average grain size based on visual estimation against a standard grain-size chart

Sample1 Dry Sand Colour Average grain size and sorting

01A 2.5Y 7/2 light grey Coarse sand, lower class; well sorted 01B 2.5Y 7/1 light grey Coarse sand, lower class; well sorted 01C 2.5Y 7/1 light grey Coarse sand, upper class; moderately well sorted 02A 2.5Y 6/1 grey Coarse sand, lower class; moderately well sorted 02B 2.5Y 6/1 grey Coarse sand, lower class; well sorted 02C 2.5Y 6/1 grey Coarse sand, lower class; well sorted 03A 2.5Y 6/1 grey Coarse sand, upper class; moderately well sorted 03B 2.5Y 6/1 grey Coarse sand, lower class; well sorted 03C 2.5Y 6/1 grey Coarse sand, lower class; well sorted 04A 2.5Y 6/1 grey Coarse sand, upper class; moderately well sorted 04B 2.5Y 6/1 grey Coarse sand, lower class; well sorted 04C 2.5Y 6/1 grey Coarse sand, lower class; well sorted 05A 2.5YR 6/1 grey Coarse sand, upper class; moderately well sorted 05B 2.5Y 5/1 grey Coarse sand, lower class; well sorted 05C 2.5Y 5/1 grey Coarse sand, lower class; well sorted 06A 2.5Y 5/1 grey Coarse sand, upper class; moderately well sorted 06B 2.5Y 5/1 grey Coarse sand, lower class; well sorted 06C 2.5Y 5/1 grey Coarse sand, lower class; well sorted 07A 2.5YR 7/2 light grey Coarse sand; moderately well sorted 07B 2.5Y 6/1 grey Coarse sand, lower class; well sorted 07C 2.5Y 7/2 light grey Coarse sand, lower class; well sorted 07D 2.5Y 7/2 light grey Coarse sand, lower class; well sorted 08A 2.5Y 7/2 light grey Medium sand, upper class; moderately well sorted 08B 2.5Y 7/2 light grey Coarse sand, lower class; moderately well sorted 08C 2.5Y 7/2 light grey Medium sand, upper class; moderately well sorted 09A 2.5Y 7/2 light grey Medium sand, upper class; well sorted 09B 2.5Y 7/2 light grey Medium sand, upper class; well sorted 09C 2.5Y 7/2 light grey Medium sand, upper class; well sorted 10A 2.5Y 6/2 light brownish grey Coarse sand, upper class; well sorted 10B 2.5Y 6/2 light brownish grey Coarse sand, upper class; well sorted 10C 2.5Y 6/2 light brownish grey Coarse sand, lower class; well sorted 11A 2.5Y 5/1 grey Coarse sand, upper class; moderately well sorted 11B 2.5Y 5/1 grey Coarse sand, lower class; well sorted 11C 2.5Y 5/1 grey Coarse sand; well sorted 12A 2.5Y 5/1 grey Coarse sand, upper class; moderately well sorted 12B 2.5Y 5/1 grey Coarse sand, lower class; well sorted 13A 2.5Y 5/1 grey Coarse sand, lower class; well sorted 13B 2.5Y 5/1 grey Medium sand, upper class; well sorted 14A 2.5Y 5/1 grey Coarse sand, upper class; moderately well sorted 14B 2.5Y 5/1 grey Coarse sand, upper class; well sorted 14C 2.5Y 5/1 grey Coarse sand, lower class; well sorted Note: 1. Samples are designated to position across beach as follows: A = mid-swash, B = base of primary dune, C = crest of primary dune, and D = secondary dune.

28 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Note: 1. Field of view is 1 mm across. 2. Images a-e show limestone grains with dark mineral inclusions 3. Image f shows a fossil coralline algae with the skeleton partly replaced by a dark mineral and the infilling of cell cavities with a pale brown stain.

Figure 4.4 Thin sections of carbonate grains viewed in reflected light

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 29

Note: 1. The scanning electron micrograph shows a micro-granula carbonate grain formed of elongate granules of <0.5 µm size, between which are developed internal dark mineral patches.

Figure 4.5 Microstructure of micro-granular carbonate grain which has dark mineral inclusions

Iron sulphide The precipitation of iron sulphide in a marine environment requires (Berner 1984):

1. Bacterial reduction of sulphate to sulphide, which is promoted by the presence of abundant organic matter facilitating anoxic conditions in the sediment; and 2. A sufficient amount of highly reactive iron (FeHR) to react with the dissolved sulphide to produce iron sulphide leading from metastable mineral forms to pyrite.

There is usually very little FeHR in carbonate sediment because of the generally low percentage of detrital iron minerals present. The total iron available in most marine environments is made up of about 25-28% FeHR, 23-31% poorly reactive iron, and 42-41% unreactive iron; but in carbonate sediment the proportion of FeHR is likely to be relatively higher than in terrigenous sediment (Raiswell and Canfield 1998). The most reactive iron is found in rust-coloured coatings of fine-grained hydrous ferric oxides that may occur on sediment grains (Berner 1984). Under the conditions outlined above, these ferric oxides will convert to pyrite.

Some grains with the dark mineral inclusions (considered to be iron sulphide) also have a brown or yellow staining (e.g. Figure 4.4e,f). This colouration is likely due to ferric oxides and indicates FeHR is present. However, many grains stained by ferric oxide show no dark mineral inclusions; and these grains often do not have the microporosity of the dark grey grains. It is therefore considered that the minute pore spaces present in the micro-granular carbonate grains provide an anoxic micro-environment in which any hydrous ferric oxide would re-mineralise to iron sulphide.

30 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Some dark grey grains show no evidence of ferric oxide staining (e.g. Figure 4.4a). Canfield et al. (1996) suggested that in some environments, dissolved Fe2+ reacts with dissolved sulphide to precipitate iron sulphide. It is possible that this scenario is also present in the micropores of the carbonate grains resulting in the precipitation of iron sulphide. The dissolved Fe2+ may be present in the sediment from migrating ground waters, and interact with high concentrations of dissolved sulphide produced after seagrass debris (wrack) has been rapidly incorporated into the carbonate sediment during, for example, winter storm disturbances. It is possible that the ferric oxide staining is a result of subsequent oxidation of the iron sulphide, rather than a precursor to the sulphide.

Maiklem (1967) examined the origin of black or brown speckled sand from the Great Barrier Reef, and noted that the main coloured grains were the tests of the foraminifera Marginopora and Alveolinella. These two foraminifera have porcellaneous walls with microporous micro- granular structure similar to the dark grains in the Owen Anchorage region. Maiklem did not examine the microstructure of the foraminiferal walls, and considered the dark mineralisation a surface coating with the iron sourced from associated terrigenous sediments.

4.2.6. Summary The 'grey' colour of the sands on the beaches of Owen Anchorage is the result of the dark mineralisation (likely iron sulphide) occurring within the microstructure of some limestone grains. The precipitation of this dark mineral within the structure of the carbonate grains is a natural process. The proportion of 'dark limestone' grains greatly affects the overall 'greyness' of the beach - with only a third required for the beach to have an overall dark grey look.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 31 5. Source and Spatial Extent of the Grey Sands

5.1. Distribution pattern The distribution of the grey sand found in the present study shows that the darkest sand is present on beaches adjacent to Success and Parmelia Banks, and the lightest sands are found at beaches in central Owen Anchorage (i.e. at the greatest distance from the banks), and at Site O1, on the northern side of the Douro Road groyne at South Beach (Figure 5.1). The beaches adjacent to Success and Parmelia Banks also have the highest percent of dark limestone, and correspondingly the highest percent occurrence of mineralisation within the carbonate grains (Figure 5.1).

Becher Point, another location with grey sands, lies at the landward end of a tombolo that extends from the Garden Island–Rottnest Dune Ridge System—this corresponds to the geological setting of the beaches with the grey sand in Owen Anchorage. Sands from the eastern beach of Carnac Island, which is part of the Garden Island–Rottnest Dune Ridge System, are also grey and have a similar composition to the Owen Anchorage and Becher Point sands.

This distribution of grey sands supports the conclusion of previous sampling studies (Oceanica 2004) and shoreline transport studies (e.g. M.P. Rogers & Associates 2004, Oceanica 2009) that sand from Parmelia and Success Banks is being transported shoreward onto the southern and northern Owen Anchorage beaches. The provenance of the sand is discussed in the following sections. 5.2. Source of limestone grains The Tamala Limestone which forms the offshore islands and reefs in Owen Anchorage is the only available source of limestone grains in this region. The provenance could be the: a) Garden Island-Rottnest Dune Ridge System; or b) Trigg Dunes of the Spearwood Dune System.

Sediment transport modelling by M.P. Rogers & Associates (2004) has indicated that sand is being transported to the Owen Anchorage beaches via Success and Parmelia Banks, and this is supported by the sand-distribution pattern found in the present study. It is therefore likely that the provenance of at least most of the limestone lies in the Rottnest Dune Ridge System.

32 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Note: 1. For each site is shown the dry sand colour (using the Munsell Soil Colour Chart), percentage of dark limestone (dl) grains and the percentage of carbonate grains with mineralisation (m).

Figure 5.1 Distribution of grey sands along Owen Anchorage beaches Distinctive fossils eroded from limestone in this dune ridge system and transported as sand to the Owen Anchorage beaches may also be used as evidence for the source of the limestone grains. The fossil foraminifera found in the sand samples collected for the present study include the following species:

Amphisorus hemprichii, Amphistegina lessonii, Baggina sp. Cibicides cf. reflugens, Cibicoides basilanensis, Clavulina pacifica, Elphidium advenum, E. crispum, E. novozealandicum, Epistomarioides polystomelloides, Gaudryina convexa, Globigerinoides sp., Globorotalia inflata, Lamellodiscorbis melbyae, Neoconorbina sp., Neogloboquadrina sp., Pararotalia nipponica, Peneroplis planatus, Planoglabratella opercularis, Planulinoides biconcavus, Pseudomassilina australis, Quinqueloculina bradyana, Q. cf. cuvieriana, Q. poeyana, Quinqueloculina polygona, Quiqueloculina spp., Reussella armata, Rosalina sp. 1, Rotorbis auberi, Sahulia sp. 1, Spiroloculina subimpressa, Textularia kerimbaensis, T. cushmani, Triloculina striatotrigonula, Triloculina tricarinata.

The fossil foraminifera found in the Owen Anchorage sand samples have assemblages similar to those found in beach sands from Rottnest and Carnac Island (D. Haig 2009, pers. comm.). Of particular importance is the presence in all samples of the planktonic species Globorotalia inflata.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 33 5.2.1. Possible sites of mineralisation As discussed in Section 4.2.5 iron sulphide mineralisation takes place under reducing conditions. These conditions can occur on two different scales:

1. Within the marine sediment profile itself - oxygen does not typically penetrate below approximately 10 cm of the sediment surface, therefore establishing an anoxic environment; or 2. Within the structure of the individual grains, where minute pores within micro-granular carbonate provide an anoxic micro-environment.

An alternative possibility is for the iron sulphide mineralisation to occur within the limestone formation, with the subsequent release of these grains as a dark-grey sediment through erosion of the limestone. To test this possibility, cores were drilled from limestone outcrops on Carnac Island, part of the Garden Island-Rottnest Dune Ridge System. Dark limestone grains similar to those found on Success and Parmelia banks and along the beaches of Owen Anchorage are not present in the cored limestone - and therefore this source of dark-grey grains seems improbable. Thus, the grey colouring is developed at some stage during transport across the banks rather than at the sediment source.

5.2.2. Timing of mineralisation It is considered most probable that the iron sulphide mineralisation of micro-granular carbonate grains is taking place across Parmelia and Success Banks. The presence of grey sand through the entire sand deposit (up to 15 m thick) that forms the banks indicates that this is not a recent phenomenon but may have been ongoing since the formation of these banks (approximately 7,000 years). Seasonal storms rework the sand in the shallow seagrass meadows and the sediment is periodically transported further eastward in steps across the bank and eventually to the mainland shore where it is redistributed along beaches by longshore drift.

34 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

6. Changes Over Time

6.1. Previous studies Grey sands are not a new phenomenon for the Owen Anchorage area, with several previous descriptions (Table 6.1) noting the grey colour of offshore sediments (e.g. Carrigy 1956, Ives 1962, Semeniuk and Searle 1985), and the consistency of this grey colour through the sediment layers of the two sandbanks (e.g. France 1977, Gunson 2000). A preliminary study (Oceanica 2004) confirmed the presence of darker sediments on the beaches within Owen Anchorage—a feature that does not generally occur at beaches north of the Swan River, or immediately south within Cockburn Sound. However, sands further south at Becher Point (Warnbro Sound) are also dark in colour.

A first-order shoreline sediment budget (Oceanica 2009) indicates that, on average, landward-directed sediment transport was much greater in the period 1972–1994 than for the period 1994–2008. This supports evidence of side-cast dredge material moving onshore and nourishing the shoreline between 1964 and 2008.

The Steedman (1977) report presents findings of a study into the processes responsible for the accumulation of the dark grey calcareous sands on the beaches in the vicinity of CCL’s washplant reclaimer; the affected zone at that time extended less than one kilometre east and west of the reclaimer jetty. It was considered that this grey sand was derived from CCL’s washplant return waters, which in 1977 were discharged across the beach. It was also noted that this discharge had created a region of shoreline accretion in the vicinity of the reclaimer jetty (up to 40 m between 1964 and 1976). The dumping of sands from the barges at the head of the jetty was not considered a significant source of grey sands at this time. The presence of both the high carbonate sands and the grey sand in the vicinity of the CCL reclaimer jetty supports the view that CCL’s operations were largely responsible for the grey sand colouration at that time. A sediment budget was constructed using estimates from stratigraphic profile data, and dumping rates from the CCL washplant. It was estimated that the volume of the grey sands (which were restricted to within one kilometre either side of the reclaimer) on the beach was between 20,000 and 25,000 m3.

Additionally, in examining the relative impacts of natural processes versus human activities, simple mass-balance calculations have indicated that approximately 80% of the shoreline change in Owen Anchorage during this time could be ascribed to historic activities which have had a direct impact on shoreline position. It was concluded that “the influence of either (i) natural variations; and/or (ii) Cockburn‘s offshore dredging activity on the long-term stability of the shoreline of Owen Anchorage are much less than that which can be attributed to the influence of historic anthropogenic works” Oceanica (2009).

Several modifications to CCL’s operations to address the grey sand issue were suggested in the Steedman (1977) report. It was considered that if these changes were made then the beach would naturally return to its original shape and also thereby reduce the colour variation of this section of beach within three to five years. It is noteworthy that all these changes have now been implemented by CCL. It is also noteworthy, that at the time of the Steedman study the grey sands were limited to the vicinity of the washplant reclaimer and were considered to be directly related to shoreline discharge from the washplant. Immediately following this study the discharge was relocated from the shoreline to the jetty and since June 2004 the discharge point is located at the end of the jetty 3m below the water surface.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 35 Table 6.1 Summary of studies on the sedimentology and stratigraphy of Holocene sand deposits in Owen Anchorage

Report Comments Kempin (1949) described the sand on Parmelia and Success banks as "very fine" with over 90% carbonate composition. The colour was not described. He suggested Kempin 1949 that the sand had been derived from the west having been transported by longshore drift along the west side of Garden Island and then eastward under the direction of the deep-sea swell. Carrigy (1956) reported on marine deposits adjacent to the islands offshore of Fremantle and noted that the sediment consisted mainly of "reworked and contemporary calcareous sands". The study was based on sediment samples Carrigy 1956 collected during 1949-1952. Grey sands were listed at water depths from 2-20 m. Carrigy (1956) concluded that the grey colour of the "fine sands" is due to "a proportion of terrigenous organic mud". As part of a broad study of Cockburn Sound sediments, Ives (1962) examined five sand samples from Parmelia and Success Banks. He noted that very little sedimentological work had been done in this region prior to his study. The samples Ives 1962 from Success Bank were described as light to dark grey fine to medium grained carbonate sand. Those of Parmelia Bank were described as grey to dark grey very fine to medium grained carbonate sand. Cores taken during March-May 1977 from sand banks in the Cockburn Sound region, including eight cores from Parmelia Bank and five cores from Success Bank (Table 1), were the basis of a sedimentological and stratigraphic study by France (1977). He recognized the following general succession for both banks, in descending stratigraphic order:

Upper unit Light grey well-sorted sand with no apparent layering. The composition is 18-45 % molluscs, 8-13% algal fragments, 14-32% “lithoskels” (= limestone fragments), 3-10% foraminiferal tests, 2-14% echinoids, and 1-12% quartz. Average grain-size varies from 0.2 mm to 3 mm. Middle unit Light to dark grey well-sorted sand with layering in places shown France 1977 by colour and grain-size (which varies from 0.1 mm to 0.7 mm). The composition is 18-30 % molluscs, 18-30% algal fragments, 18-25% “lithoskels” (= limestone fragments), 3-11% foraminiferal tests, 2-15% echinoids, and 2-10% quartz. Lower unit Light grey moderately well-sorted sand with very minor carbonate mud content. Average grain-size is about 0.4 mm. Composition is 23-35% molluscs, 21-26% algal fragments, 19-27% “lithoskels” ( = limestone fragments), 5-10% foraminiferal tests, 9-13% echinoids, and 3-7% quartz.

Thin sections from each unit are housed in the collections of the Earth Science Museum in the School of Earth & Environment at the University of Western Australia. Following observations of grey sands in the vicinity of CCL’s washplant CCL commissioned a study. Data are presented from a series of three profile surveys undertaken in July 1976, October 1976 and February 1977. Wind and wave measurements/observations are also presented. A series of beach cores were obtained and two trenches were sampled to examine the vertical extent of the grey sands. It was noted that the grey colouring was dredged shellsand material and did not represent any toxic or chemical contamination; therefore the issue is one of aesthetics only. The grey sands were generally found in a discrete layer above the light coloured sands, up to 0.3 m thick and laterally extending less than one kilometre east and west of the jetty. The grey sand layer sloped seawards, thinning eastward along the beach and southward towards the dunes. The sands in the vicinity of the Washplant had up to 95% carbonate content, compared to the 60 to 70% carbonate content of the sands of South Coogee beach. Also, the carbonate Steedman 1977 content analysis indicated a sharp boundary in beach sediment characteristics where the extension of the northern edge of Parmelia Bank would intersect the shoreline. It was suggested that area was a sediment sink area and that relatively little sand travels southward from Coogee beyond this point. It was considered that this grey sand was primarily derived from CCL’s washplant return waters (the dumping of sands from the barges was not considered a significant source of the grey sands) which discharged at the shoreline. It was also noted that this discharge had created a zone of shoreline accretion in the vicinity of the discharge point.

Two major sediment movement zones were described: (1) littoral drift, which occurs along the shoreline due to breaking waves and swash movement; and (2) inshore sediment movement between the beach and the northern edge of Parmelia Bank. The littoral drift sediment movement was considered to be responsible for

36 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Report Comments transporting sediment both to the east and west of CCL’s Washplant jetty; however, as south-westerly waves predominate, it was considered that the majority of sediment in the littoral zone is transported to the east. The inshore sediment transport zone occurs between water depths of 2 to 10 m. It was considered that a net westerly sediment movement prevailed in this zone which is extenuated under storm or high energy conditions. A general description of beach sand facies in south-western Australia was presented by Semeniuk & Johnson (1982). Coogee Beach was one of the beach sites for this Semeniuk & Johnson study but no specific information on the beach was presented. Semeniuk & Johnson 1982 (1982) explained how different sedimentary process operated on the shoreface, foreshore, backshore and beach ridge/dune zones to produce sediment layering of different grain size and composition. Searle (1984) noted that the bank sediment is mainly homogeneous and typically a "moderately sorted skeletal-fragment, lithoclastic sand with minor amounts of Searle 1984 quartz". The grey colour was attributed to "black pigmentation on the carbonate grains". The sand comprising Parmelia Bank was formally defined as the Becher Sand by Semeniuk & Searle (1985). A core site at the western end of Woodmans Point was Semeniuk & Searle designated as type section. It comprises "grey, structureless to bioturbated, 1985 medium and fine sand composed of quartz and skeletal grains" and is 10 m thick. Radiocarbon ages of younger than 7000 C14 yrs BP were reported for the Becher Sand. Semeniuk & Searle (1987 formally defined the Birdport Calcilutite for the carbonate mud unit underlying the Becher Sand and accumulating at present in deep basins in Cockburn and Warnbro Sounds. They noted that shells from the Birdport Calcilutite Semeniuk & Searle yielded radiocarbon dates of younger than 7000 C14 yrs BP. Semeniuk & Searle 1987 (1987) suggested that the carbonate mud in the deep-water basins was derived from adjacent sea-grass banks (such as the Parmelia and Success banks) through winnowing of fine sediment by wave agitation. Searle et al. (1988) described a sedimentation model for beach and bank sand facies in the study region. They noted that sand from the "seagrass lithotope" of the bank facies was generally grey and that this colouration was due to "staining by iron sulphide". Sand of the lower shoreface "sand wave/sand flat lithotope" consists of Searle, Semeniuk & "well-sorted medium sands composed largely of skeletal fragments and lithoclasts". Woods 1988 Layering and cross layering is present in this unit. The beach facies consists of "medium to coarse skeletal and lithoclast carbonate sand with a minor, variable quartz component". The beaches are zoned with "layered medium sand and shelly sand in the backshore zone" and "laminated medium to coarse shelly sands in the swash or foreshore zone". Searle & Semeniuk (1988) noted the importance of carbonate "lithoclasts" (= limestone fragments) in beaches between Cape Bouvard and Trigg Island. They Searle & Semeniuk noted that beaches closest to eroding offshore ridges contain the highest relative 1988 abundance of limestone fragments in the beach sand. The colour of the sand was not discussed. Carbonate samples, from Success Bank, were submitted for radiocarbon dating. Analysis indicated that Success Bank was initiated at approximately 6,000– D.A. Lord & 7,410 14C years before present. This suggests that the initiation of development of Associates 1998 Success Bank approximately coincided with sea level inundation of the basal level of Success Bank during the Holocene transgression. In a report for CCL, Gunson (2000) presented logs of 194 sediment cores from Success and Parmelia banks obtained by a vibracoring technique. Many of the cores sampled the entire carbonate sand succession (up to about 15 m thick) and three stratigraphic units were recognized. These are listed below in descending stratigraphic order:

Unit A (top) Dark grey to grey, well-sorted and rounded, coarse grained sand. Gunson 2000 Calcium carbonate content is generally > 90% and modal grain size is usually 0.3- 0.15 mm. Unit B Grey to light grey, well sorted, medium to fine grained sand. Calcium carbonate content is generally > 90% and modal grain size is typically 0.3-0.15mm. Unit C (base) Light greenish grey to dark greenish grey, moderate to poorly sorted, fine grained silty sand. Calcium carbonate content is generally between 80% and 90% and modal grain size is typically 0.15-0.075 mm. Skene et al. (2005) provided a brief description of the sediment on the carbonate banks around Cockburn Sound. They noted a light grey to grey colour, a high Skene et al 2005 calcium carbonate content (about 90%), and an average mean grain size of 0.34 mm. Their north-south cross-section, based on cores, from Parmelia Bank across the basin of Cockburn Sound shows the Becher Sand of Parmelia Bank

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 37 Report Comments prograding across the Birdport Calcilutite of the basin. Geochemical analyses of the fine fraction of the carbonate sand from Parmelia Bank found low to moderate Nd/Sr, moderate Zn, and high Cu and Ni values. MPRA (2004) analysed recent changes in shoreline and demonstrated that substantial variation occurred along the Owen Anchorage beaches during the 1999- 2003 interval. The study indicated a net sand accretion on the beaches of Owen Anchorage over the five-year period. Progradation of the shoreline apparently was responsible for a seaward advance in the vegetation line by as much as 20 m (e.g. at South Beach) between 1999 and 2003. At other places substantial erosion MP Rogers & occurred (e.g. at Northern Dog Beach). Associates (MPRA)

2004 Modelling of sediment fluxes in the Owen Anchorage area by MPRA (2004) indicated that sediment is transported in an eastward direction across Parmelia and Success banks. The northern beaches of Owen Anchorage, as far south as Coogee Beach, receive sediment from Success Bank at an estimated rate of 21,600 m3/yr. Woodman Point, and the southern beaches of Owen Anchorage receive sediment from Parmelia Bank at an estimated rate of 15,900 m3/yr. Oceanica (2004) determined the colour of a surface sand sample from the crest of the foreshore at 23 beach sites between Swanbourne Beach and Cape Peron. In addition hand-augered cores were obtained at four sites to ascertain the colour Oceanica Consulting variation in a vertical section through the sand, and additional surface samples were Pty Ltd 2004 collected from dunes at North James Rocks and Coogee Beach. The study confirmed the occurrence of grey sand on Owen Anchorage beaches, and also found variation in colour in the vertical cores. Gozzard (2007) undertook a survey of beaches in the vicinity of Owen Anchorage and found that grey sand was present between Catherine Point, Fremantle and West Gozzard 2007 Beach, Woodman Point. He found variation in the distribution of grey sand on the beaches, and suggested that the source of the sand was from Success and Parmelia Banks. A simple sediment budget estimate for the period of CCL’s dredging (1972–2005) and suggests an onshore sediment transport rate from Success Bank of 29,000 m3/yr and Parmelia Bank of 32,000 m3/yr. The onshore sediment flux for Oceanica Consulting Parmelia Bank presented in this report is approximately double that previously Pty Ltd 2009 presented in MPRA 2004. However, it appears that this is due to the inclusion of ~16,000 m3/yr shoreline of accretion between the WAPET groyne and Woodman Point rock groyne.

6.2. Vertical sediment profiles Sediment cores taken from the south beach at Woodman Point show an upper shoreface sand-facies unit overlying a lower seagrass-meadow sand-facies unit (Figure 6.1). Significant progradation of the shoreline has taken place on this beach during the last 30 years (Figure 6.1) and shoreface sand has progressively overlain sand deposited in the seagrass meadow. The seagrass meadow facies has grey sand, whereas layers of pale and darker sand form the shoreface facies. The light-coloured biogenic grains tend to have internal cavities and are usually of irregular shape. The dark limestone grains are solid and more rounded. The presence of grey sands throughout the sediment core collected between the Woodman Point and WAPET groynes indicates that they grey sands have been transported onshore for at least the last 30 years.

Due to the differences in grain shape and size, sorting of grains with different colour takes place as can be observed in the present-day swash zone. Coarser-grained pale biogenic sand is concentrated in the higher-energy zones (such as the wave-breaking zone), whereas darker slightly finer grained sand dominated by limestone grains forms the upper swash zone. This compositional difference is apparent on most beaches along Owen Anchorage (Table 4.8), and was described as typical of beaches in this region by Semeniuk & Johnson (1982) and Searle et al. (1988).

A number of shallow beach sediment profiles were captured within Owen Anchorage, and observations indicated that grey sands were typically present throughout the first metre of beach sediment (Table 6.2).

It is considered likely that there would be some natural variation in the proportion of grey limestone particles transported to the coast each year. This variation would be due to a number of factors including storminess, wrack presence and sediment turnover (i.e. amount

38 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

of time the limestone particles would be exposed to reducing conditions). As shown in Section 4.2, small changes in the proportion of grey particles can have a significant effect on overall sand colour.

Figure 6.1 Sediment core from beach between Woodman Point and WAPET groynes

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 39 Table 6.2 Description of colour variation shown at selected sediment profile sites

Site No. Location Description Photo

Berm scarp sampled, very little colour South O2_2A variation throughout the approximately Beach one metre scarp

Catherine Dune profile sampled, very little colour O3_2B Point variation throughout.

Surface sample was collected from the back of the beach, showing grey coloured sands. Additional photos were Coogee taken of a trench being dug by others— O8_2A Beach little colour variation observed in the ~0.5 m depth. No further sampling was completed at Coogee due to the recent bypassing works.

Auger to depth of ~0.75 m showed grey Jervoise Bay sands throughout, although becoming O12_2A Yacht Club slightly darker and coarser down towards the core base

40 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Site No. Location Description Photo

Samples were collected from behind the primary dunes. There appeared to be a thin layer of grey sands on the surface O12_2C Jervoise Bay with lighter (brown-ish) material O12_2D Yacht Club underneath. This layer decreased in depth with increasing distance from the coast.

Auger to depth of ~0.85 m (water table present at this level). Profile showed a darker grey surface layer of ~0.35 m, B1_2A Becher Point before becoming a lighter grey. Similar pattern found at site B1_2B with an auger depth of ~0.9 m.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 41 7. Conclusions

7.1. Report summary The sampling, analysis and literature reviews provided in this report have been undertaken to review the following three key issues:

1. The cause of the grey coloured sands; 2. The source and spatial extent of the grey sands; and 3. The changes over time in the presence of grey sands.

A summary of the information relevant to each of these questions is provided in Table 7.1.

It has been identified that the grey colouration of the sands in Owen Anchorage is due to a natural phenomenon and not a result of contamination. Limestone, one of the three grain types found on the beaches, can have a micro-granular internal structure - and it is within the very small internal structures of individual sand grains that iron sulphide (a dark coloured mineral) can be precipitated under anoxic conditions. These dark patches within the internal structure of the grain give the grain a grey colour, and following transport and accumulation at the beach, it is these individual grains that result in the beaches of Owen Anchorage having an overall grey colour.

Two offshore banks (Success and Parmelia Banks) are the main source of sediment supplied to the Owen Anchorage beaches, and these banks are grey throughout their 15 m depth profiles, an observation made in studies undertaken as early as the 1960's. Thus, there would likely have always been a supply of grey sands onto the Owen Anchorage beaches. Further, grey sands are also present at other sites, namely Becher Point (as sampled in this study), but also Tern Island in northern Warnbro Sound, and Southern Flats in Southern Cockburn Sound. These are all locations where there is a direct sediment transport pathway to shore from the offshore limestone island/reef chain (the Garden Island - Rottnest Dune Ridge system). The presence of sand banks or tombolos appears to be a key feature in the grey sands phenomenon. It is likely that these banks provide the opportunity for the limestone particles to be exposed to anoxic conditions (in the presence of high organic matter content possibly derived from seagrasses and/or algae) during their transport onshore.

It is also considered likely that there will be some natural variation in the proportion of grey limestone particles transported to the coast each year. This variation would be associated with a number of factors including storminess, the presence of wrack and sediment turnover (i.e. the amount of time the limestone particles would be exposed to reducing conditions). As shown in this study, small changes in the proportion of grey particles can have a significant effect on overall sand colour.

Therefore, it appears that the grey sands of the beaches of Owen Anchorage are due to a combination of the following factors:

1. Erosion of the Tamala Limestone from the Garden Island - Rottnest Dune Ridge System to release micro-granular (as well as other) carbonate grains. 2. Transport of these grains eastward across Parmelia and Success banks under the influence of the dominant ocean swell and subject to seasonal storm events. 3. Exposure of these grains to reducing conditions across the sediment banks, so that iron sulphide mineralisation occurs within the grains. 4. Eventual transport of the dark limestone grains to the mainland shore and then to beaches along the southern and northern shorelines of Owen Anchorage.

A key question is whether human activities are enhancing ‘greyness’ of some beach sediments as suggested by Steedman (1977). In an ideal case (where the various sediment’s sources, pathways and deposition zones are well documented and the rates of transport are known over periods of decades or more) it might be possible to distinguish the ‘signal’, generated by human activities, from the ‘noise’ of the natural variations. This signal could then be quantified, allowing construction of a notional ‘hierarchy of causation’. Unfortunately, this detailed information does not exist for Owen Anchorage. However, it is

42 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

known that the changes along the shoreline are dominated by human-induced change. Indeed, the available evidence indicates that natural factors and historical human activities at the coastline probably cause coastal change perhaps four times greater than that associated with other human activities in the area (Oceanica 2009). As a result, because of the potential causes of the greyness of the beaches (Section 1.1), it is likely that variations in the greyness of beach sediments in the area are similarly influenced.

Table 7.1 Cause and extent of the grey sands in Owen Anchorage

Issue Summary  Beach sands are not contaminated.  Sands on the beaches of Owen Anchorage are made up of particles of a variety of colours.  The grey colour of some limestone particles is due to a natural process of iron sulphide precipitation within the internal structure of the sediment grains under anoxic conditions.  The staining of these limestone grains occurs across the banks during the onshore transport of the Cause of the grey coloured sands sediments to the mainland.  The proportion of limestone particles with this iron sulphide staining greatly influences the overall colour of the beach sands (having approximately 30% of these grains will give the beach an overall dark grey colour).  Beach sands can look darker when wet due to the carbonate becoming transparent, and consequently making the dark iron sulphide more apparent.  Grey sands are present throughout Owen Anchorage beaches and primary dunes.  Grey sands are also present in other Perth metropolitan locations including Becher Point, Tern Island and Southern Flats. Source and spatial extent of the grey sands  Main source of limestone grains to the Owen Anchorage shoreline is the Garden Island Rottnest Dune Ridge system.  These limestone grains are transported eastwards across Parmelia and Success Bank to the shoreline at Woodman Point and Catherine Point respectively.  Studies dating back to the 1960's refer to grey sands being present in the Owen Anchorage area.  Sands within the offshore banks are grey throughout the full depth of their sediment profile (~15 m below Temporal extent of the grey sands seabed), representing up to ~7,000 years.  Sediment cores at Woodman Point indicate that accumulation of grey sands at the beach has occurred throughout the last 30 years.

7.2. Management strategy Given that the grey sands present on Owen Anchorage beaches is a natural phenomenon and that the issue is one of aesthetics, the recommended key management strategy of this issue is to enhance the education of the key stakeholders and local community.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 43 8. Acknowledgements The field surveys were conducted by Michelle Carey, Bruce Hegge, Tanya Stul, Colin Hart and Lotte Rivers (Oceanica Consulting), David Haig (University of Western Australia) and Steve Cossington (Marine and Freshwater Research Laboratory, Murdoch University).

Sediment contaminant analyses were completed by the National Measurement Institute. Sediment characterisation was completed by the University of Western Australia.

This report was prepared by Michelle Carey and Katharine Cox (Oceanica Consulting) and reviewed by Bruce Hegge (Oceanica Consulting) and Tom Rose (Cockburn Sound Management Council). GIS figure preparation was completed by Philip Kindleysides (Oceanica Consulting). Final edits were made by Piers Larcombe (Oceanica Consulting). This report was formatted by Rachael Hillman (Oceanica Consulting).

44 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

9. References ANZECC/ARMCANZ 2000, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, National Water Quality Management Strategy No.4. Berner, R.A. 1984, Sedimentary pyrite formation, Geochimica et Cosmochimica Acta, Vol. 48, pp. 605-615. Canfield, D.E., Lyons, T.W., and Raiswell, R. 1996, A model for iron deposition to euxinic Black Sea sediments, American Journal of Science, Vol. 296, pp. 818-834. Carrigy, M. A. 1956, Continental Shelf Sediments of South-Western Australia, M.Sc. Thesis, Department of Geology, The University of Western Australia. D.A. Lord & Associates 1998, Radiocarbon Dating of Success Bank, Owen Anchorage (Western Australia), Prepared for Cockburn Cement Limited by D. A. Lord & Associates, Report no. 95/008/2, Perth, Western Australia, October 1998. DCE 1979, Cockburn Sound Environmental Study 1976–1979, Report No. 2, Department of Conservation and Environment, Western Australia. DoE 2003 Draft, Assessment Levels for Soil, Sediment and Water, Contaminated Sites Management Series, Draft for Public Comment, Department of Environment, Western Australia. EPA 2005a, Environmental Quality Criteria Reference Document for Cockburn Sound (2003- 2004), A supporting document to the State Environmental (Cockburn Sound) Policy 2005, Environmental Protection Authority, Report No. 20. EPA 2005b, Manual of Standard Operating Procedures for Environmental Monitoring against the Cockburn Sound Environmental Quality Criteria (2003-2004), A supporting document to the State Environmental (Cockburn Sound) Policy 2005, Environmental Protection Authority, Report No. 21. France, R. E. 1977, The Origin and Sedimentology of Barrier and Fringing Banks, Cockburn Sound, Western Australia, B.Sc. (Honours) Thesis, Department of Geology, The University of Western Australia. Gozzard, J. R. 2007, Report of investigations into grey beach sands along the beaches of Owen Anchorage, Geological Survey of Western Australia, November 2007. Gunson, M. 2000, Geotechnical evaluation of the shellsand resources in the Owen Anchorage and Mewstone regions, Western Australia, Report for Cockburn Cement Ltd., Department of Geology & Geophysics, The University of Western Australia. Hearn, C. J. 1991, A Review of Past Studies of the Hydrodynamics of Cockburn Sound and Surrounding Waters with an Appraisal of Physical Processes and Recommendations for Future Data Collection and Modelling, Prepared by Australian Defense Force Academy Department of Geography and Oceanography, Campbell, ACT, May 1991. Ives, W. A. 1962, The Recent Sedimentation and Palynological Studies in Cockburn Sound, Western Australia, B.Sc. (Honours) Thesis, Department of Geology, The University of Western Australia. Kempin, E. T. 1949, The problem of sand movement in Cockburn Sound and approaches to Fremantle, Western Australia, and its application to beach erosion problems at Cottlesloe, WA, Fourth-Year Thesis, Department of Geology, The University of Western Australia. Le Page, J. S. H. 1986, 'Building a State - the story of the Public Works Department of Western Australia 1829 - 1985', in, Perth, Western Australia. Maiklem, W.R. 1967, Black and brown speckled foraminiferal sand from the southern part of the Great Barrier Reef, Journal of Sedimentary Petrology, Vol. 37, pp. 1023-1030. M.P. Rogers & Associates (MPRA). 2004, Owen Anchorage Shoreline Monitoring (1999-2003), Prepared for Cockburn Cement Limited, Job J177/6, Report R133.

Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands 45 Oceanica 2004, Sediment colour of Southern Perth beaches, Field Observations and Data Report, Report No. 336/5, prepared for Cockburn Cement Ltd, by Oceanica Consulting Pty Ltd, Western Australia. Oceanica 2007, The State of Owen Anchorage: A Pressure State Response Report, Prepared for Cockburn Sound Management Council by Oceanica Consulting Pty Ltd, Report no. 508/1, Perth, Western Australia, February 2007. Oceanica 2009, Cockburn Cement’s Environmental Management Programme: Shoreline Monitoring Plan, Owen Anchorage—Synthesis Report, 2003–2006, Report No. 334_342/1, Prepared for Cockburn Cement Ltd, by Oceanica Consulting Pty Ltd, Western Australia. Raiswell, R. and Canfield, D.E. 1998, Sources of iron for pyrite formation in marine sediments, American Journal of Science, Vol. 298, pp. 219-245. Searle, D.J. 1984, Sediment Transport System, Perth Sector Rottnest Shelf, Western Australia, PhD Thesis, University of Western Australia. Searle, D. J. & Semeniuk, V. 1985, The natural sectors of the inner Rottnest Shelf coast adjoining the Swan Coastal Plain, Journal of the Royal Society of Western Australia, Vol. 67, pp. 116-136. Searle, D. J. & Semeniuk, V. 1988, Petrology and origin of beach sand along the Rottnest Shelf coast, Southwestern Australia, Journal of the Royal Society of Western Australia, Vol. 70, pp. 119-128. Searle, D. J. Semeniuk, V. & Woods, P. J. 1988, Geomorphology, Stratigraphy and Holocene history of the Rockingham-Becher Plain, south-western Australia, Journal of the Royal Society of Western Australia, Vol. 70, pp. 89-100. Semeniuk, V. & Johnson, D. P. 1982, Recent and Pleistocene beach/dune sequences, Western Australia, Sedimentary Geology, Vol. 32, pp. 301-328. Semeniuk V. & Searle, D. J. 1985, The Becher Sand, a new stratigraphic unit for the Holocene of the Perth Basin, Journal of the Royal Society of Western Australia, Vol. 67, pp. 109- 115. Semeniuk, V. & Searle, D. J. 1987, The Birdport Calcilutite, Journal of the Royal Society of Western Australia, Vol. 70, pp. 25-27. Skene, D., Ryan, D., Brooke, B., Smith, J. & Radke, L. 2005, The geomorphology and sediments of Cockburn Sound, Geoscience Australia, Record 2005/10, 88 pp. Steedman 1977, A Study of Grey Calcareous Sand, Beach Colouration - Woodman Point, Prepared for Cockburn Sound Ltd by R.K. Steedman & Associates, Perth, Western Australia, June 1977

46 Oceanica: CSMC: Sand Colour of Owen Anchorage Beaches; Investigation into the occurrence of grey sands

Appendix A

Coastal structures, dredging and beach nourishment within Owen Anchorage

Table 1 Coastal structures within Owen Anchorage

Location Work Year (s) Why constructed Rock training North Mole 1892-1902 Maintain navigable Inner Harbour. ≈1,460 m length wall Rock training South Mole 1894-1902 Maintain navigable Inner Harbour. ≈620 m length wall Arthur’s Head Rock seawall ? Challenger Built onto the Northern breakwater of the Fishing Boat Breakwaters 1984-1987 Harbour Harbour 1920, Fishing Boat Northern extended Constructed near the site of the Long Jetty southwards Harbour Breakwater in 1938, 1947 1960-62, Fishing Boat Southern extended To provide additional protection for boats in Fishing Harbour Breakwater in 1966- Boat Harbour 67, 2003 Success Southern Constructed at Scott St to create another Harbour 1978-1979 Harbour Breakwater adjacent to Fishing Boat Harbour southern breakwater South of Breakwater extended as part of South Beach Success Rock revetment 1996 redevelopment to stop car park being inundated by Harbour sand As part of three stage South Beach restoration. The 1965, final stage was the construction of the Duoro Rd groyne Duoro Rd Rock groyne extended with nourishment north of the structure. 91.5 m, in 1996 extended 60 m in 1996. Contains a stormwater drain Duoro Rd Seawall 1996 Seawall on either side of Duoro Rd groyne As part of three stage South Beach restoration. The second stage was the construction of the Island St 1962, groyne with nourishment north of the structure from Island St Rock groyne extended offshore dredging [in 1964/65]. 107 m, extended 80 m in 1996 in 1996. Additional rock revetment protection placed on south side of the groyne in 2006

Initially designed to reduce sedimentation of the South Fremantle Power Station (SFPS) holding basin. Formed 1959, part of three stage South Beach restoration. The first Catherine Point Rock groyne extended stage was the proposed 107 m Catherine Point groyne, in 1962 with behaviour observed over next three years. Groyne extended 61 m in 1962 due to saturation

South 1949, Fremantle Constructed to reduce the quantity of sediment infilling Groyne no. 3 extended Power Station the SFPS holding basin in 1960? (SFPS) Constructed as a holding basin for intake water. Groyne no.1 is the southern (~180 m) with the discharge pipe South Groynes No. 1 cut through it. Groyne no. 2 is the northern (~165 m). Fremantle 1946/7 and 2 Groynes were joined by a bridge. Rapidly filled with Power Station sediment and the intake pipe was extended offshore. Two walls constructed within the basin South 1948, Constructed in response to erosion south of the SFPS Fremantle Rock Revetment extended intake groynes. Originally ~45 m, extended to ~225 m Power Station in 1949 Port Coogee 2 Breakwaters 2006 Sheltering for Port Coogee development Anchorage Rock revetment Assumed to be constructed to protect Anchorage 1942-54 Butchers and stub groyne butchers and other facilities 1960, Constructed for recreational use by Fremantle Ports on extended behalf of Town of Cockburn. Multiple landward Coogee Jetty Timber jetty landward extensions up to 19 m were required pre-1974 due to pre-1974 shoreline erosion 1903-4, Built as a location for unloading explosives for when Explosives Timber and extended Quarantine Station became an explosives reserve, as Jetty concrete jetty in 1938- Robb's Jetty was no longer safe 40, 1948 1913-18, Initially constructed in 1913-1918 and extended in Cockburn Seawall ext. approximately 1989 from the original Woodman Point seawall ≈1989? rock groyne in front of the yacht club Steel and timber Used for Cockburn washplant operations. The jetty is Cockburn jetty 1971 jetty 125 m long, 4 m wide at landward end and 10 m wide

at fendering system West Australian PETroleum Pty constructed this groyne WAPET groyne Rock groyne 1967 with platform at the end to drill (unsuccessfully) for oil. Has caused extension of Woodman Point Constructed as part of plan to turn whole peninsula into a Naval Base prior to WWI. Groyne was to be 2,000 m Woodman Point Rock groyne 1913-18 long and included 400 m of reclamation. Plan abandoned in 1918 Pre-1942 Jervoise Bay 1 Breakwater (≈1913– 1918) Sheltering for Northern Jervoise Bay Harbour, northern Jervoise Bay 2 Breakwaters 1991-1997 breakwater an extension/modification of breakwater above Jervoise Bay Breakwater 2001-2003 Sheltering for Southern Jervoise Bay Harbour

Table 2 Obsolete coastal structures previously within Owen Anchorage

Location (ordered Removal Work Year (s) Why constructed north to year south) 1872, ext. Mid- Constructed as main berthing jetty. Firstly constructed Fremantle 1886, Anglesea 1921 in a SW direction and extended west. Total length Long Jetty 1888, Point was ~1,150 m. Rendered obsolete by Inner Harbour 1891, 1896 It was ~150 m long and was Fremantle's main East end of South Bay 1854- berthing facility until the Long Jetty was built. Situated Anglesea ~1950 Jetty 1855 on site of Reveley's old stone jetty (no further Point reference). Breakwater extended on jetty area ~1950 Between Scott's Location of remnant Scott's Jetty identified on a map Collie & pre-1886 Jetty dating 1886. No further reference found Essex Sts Timber Supersed Cliff St to Breastwor ed in 1893 Placed because subdivision allowed to water's edge Grey St k/ 1896, piling 1903 Supersed Cliff St to Stone Assumed to reinforce the timber work. Would have 1896 ed in Grey St walling required some minor reclamation 1903 Supersed Cliff St to Stone Wall enclosed new reclamation at Marine Terrace. In 1903 ed by South St walling combination with 1903 reclamation for railway 1957 Arundel St Sea Baths 1895 1917 Recreational facility Watering This watering jetty was presented on a map dating Arundel St pre-1886 ? Jetty 1886. No further reference found South St to Stone 1903- Main seawall extended along foreshore to Scott St. No ? Scott St walling 1924 beach in front of wall. Required reclamation South Jetty (ca. 1916, extended in 1925, storm damaged Beach and destroyed 1956), baths, hydrodome (ca. 1923, Duoro Rd Jetty & 1916 1964 demolished 1964), diving tower, shark proof net (ca. recreation 1921), band stand, dancefloor in the water, dressed al area seawall North of Stone Supersed Stone walling with apron constructed in the vicinity of Duoro Rd to revetment 1927 ed in the South Beach recreational area following 1926 Island St with apron 1956 storm to protect railway. Severely damaged in 1950s Constructed both N and S of Douro Rd in response to North of Short 1926 severe storm that narrowed the beach and Duoro Rd to timber 1927 1950 threatened the ornamental wall. Groynes fell into Island St groynes disrepair, were neglected during WWII and by 1950 were completely destroyed Placed to arrest erosion, in response to destruction of Tipped timber groynes and retreat of the beach, and severe stone and Supersed erosion in winter of 1955. By 1961, beach had eroded Duoro Rd to timber 1956 ed in as much as 60 m and railway line was threatened. Island St breastwor 1965 Subsidence (up to 1.5 m), removal of fines by ks overtopping. Superseded by South Beach redevelopment Bradford Tipped pre-1954 Supersed Bradford Kendall (now known as ANI Bradken)

Kendall limestone ed by Foundry was established on high ground adjacent to seawall onshore beach. Tipped limestone wall to prevent further and jetties sediment damage to the property supply Barge and Lost Barge and boat wreck that behaved as a semi- ~1966- Robb Rd boat function detached breakwater, sustaining sand to the north and 1971 wrecks ~1987-90 reducing supply to the south 1892, ext. in Constructed to unload munitions and stock for the 1910, ~1972- Robb Rd Jetty abattoirs. Contained a stormwater drain. Remnant 1943-44, 1975 jetty piles still remain lowered in 1947 Early Barque wreck that behaved as a semi-detached Omeo Boat 1894 1960s lost breakwater, forming a tombolo and sustained sand to wreck wreck function the north Constructed to quarantine troops returning from WWI Quarantine Jetty ~1909 1972 and thereafter other diseases [small-pox, foot-and- Jetty mouth] Remnant piles still Woodman present ~1885 or Point West Jetty following WWI Beach severe shoreline erosion

Table 3 Reclamation, beach renourishment and dune creation within Owen Anchorage

Volume Location Work Year(s) Associated work (103 m3) 2.8 ha of land reclaimed as part of the railway Arthurs Head Reclamation 1903 project. Kempin (1949) suggests this filled in a ≈90 to Norfolk St lagoon with an offshore bar Anglesea Pt to Reclamation for fishing boat harbour facilities. Reclamation 1955 Collie St With timber piling surrounding the reclamation South St to Reclamation 1956 Associated with stone walling construction Scott St As part of three stage South Beach restoration. Nourishment occurred in combination with the Scott St to Nourishment 1965 construction of the Duoro Rd groyne. Volumes ≈60 Duoro Rd are approximate. Sediment sourced from nearshore dredging

Dunes created, brushed and vegetated to restrict Scott St to Dune 1984- sand movement onto roads, carparks and the Island St (or ≈31.8 construction 1986? railway, with groyne maintenance prior to Catherine Pt) America’s Cup

Extend land 60 m westward into water. With Nourishment Scott St to dune creation behind. As part of South Beach and dune 1996 ≈120 Island St redevelopment. Sediment sourced from construction nearshore dredging As part of 3 stage South Beach restoration. Nourishment occurred in combination with the Duoro to 1964- Nourishment construction of the Island St groyne. Volumes ≈61.2 Island St 1965 are approximate. Sediment sourced from nearshore dredging There was localised raising (1.5 m) of dunes South of Temporary south of Catherine Point in March 2001 due to Catherine sediment 2001 sand storage from construction works. Assumed Point groyne storage to be removed Reclamation In conjunction with Woodman Point groyne (aka Woodman to extend 1913- Long Mole) to be 2,000 m long. To turn the ≈200 Point 400 m 1918 peninsula around Woodman Point into a naval seaward base. Abandoned in 1918 Woodman Sediment 1972- Based on calculations in Steedman (1977) it was 64

Volume Location Work Year(s) Associated work (103 m3) Point discharge 1978 determined that approximately 80,000 m3 had from accumulated at Quarantine Beach (Eastern Cockburn’s Segment C and Segment D) from 1972–1978. washplant to The reject sands disposal practice was ceased in shoreilne 1978 (CCL 1986). This volume was based on discharge rates of 5 tonnes/hr from 1972–1974 and 2 tonnes/hr from 1975–1978. This was assumed to settle to a density of 1.31 tonnes/m3. Steedman (1977) had calculated an effective settling of 52,000 m3 over the first five years. Continuing with this rationale, it was approximated this was calculated using 10 hour effective days for 365 days a year. Extending this to the full seven year period, a total of 64,000 m3 was discharged. Offshore of Infill of Infill of previous nearshore dredging to mitigate Cockburn 2004 ≈50 dredged holes erosion of southern end of Quarantine Beach Seawall This has been repeatedly required with Infill behind Replenish replenishment of sediment removed from behind Cockburn Ongoing sediment the seawall NE of Cockburn. Approximately two Seawall yearly. Most recently in 2001? Dune Early Dune stabilisation with fencing, fenced pathways Coogee Beach stabilisation 1980’s and replanting Woodman Mid-late Beach nourishment using sediment excavated to Point West Nourishment ≈200 1970's float an oil rig construction Beach

Table 4 Dredging within Owen Anchorage

Volume Disposal Location Work Year (s) Dredged Reason Location (103 m3) 1892-1903, 8,600 rock Reclamation Dredging Fremantle deepened and sand and to the and bar Harbour facilities Harbour 1913-1929, (1892- north of North removal and 1989? 1903) Mole Challenger & Dredging ? Harbour facilities Success Harbours Allow navigable depths Harbour Fishing Boat Dredging 1961-1962 573 with expansion of reclamation Harbour Fishing Boat Harbour works 250-500 m Beach nourishment as offshore of South Dredging 1996 ≈120-160 part of South Beach South Beach Beach development 100-400 m offshore of ANI Beach nourishment as Island St Bradken seawall Dredging 1964-65 ≈120 part of 3 stage South groyne to to N of Duoro Rd Beach restoration South Beach groyne Deepening at end of the Explosives Jetty Dredging 1903-04 ? jetty for access During WWI to gain access to Henderson Navigation Parmelia & Naval Base. Success channel 1913–1918 Side-cast? Success Channels Channel depth 6.1 mCD dredging Parmelia Channel depth 4.3 mCD Navigation During WWII for naval Parmelia & channel 1942–1945 2,140 purposes. Channel Side-cast? Success Channels dredging depth to 7.6 mCD Navigation For deep anchorage in Side-cast Parmelia & channel 1953–1955 ≈6,100 Cockburn Sound, and/or disposal Success Channels dredging Channel depth to to location on

11.6 mCD and width of Success Bank? 152.5 m. Deepened to allow Navigation vessels with 70,000 Parmelia & channel 1966–1967 tonnes capacity to enter Unknown Success Channels dredging Cockburn Sound. Depth of 13.7 mCD. Dredging for Outer Harbour to allow deeper Navigation draft vessels Parmelia & channel 1994 (particularly BP oil Success Channels dredging tankers). To depth 14.7 mCD and restored width of 152.5 m Maintenance dredging of the western margins Fremantle Ports of the shipping Maintenance Every two Cockburn’s Maintenanc channels. Operates for Dredging of to three 30-40 lime/cement e dredging about two weeks at a Parmelia & years production time. To maintain depth Success Channels of 14.7 mCD and width of 152.5m

Appendix B

Contaminant Laboratory Reports

A__u_s_t_ra_l_i_a_n_ G__o_v_e_r_n_m_e_n_t______National Measurement Institute

REPORT OF ANALYSIS Page: 1 of 9 Report No. RN685057 Client : OCEANICA CONSULTING Job No. : OCEA26_W/080522 PO BOX 3172 Quote No. : QT-01447 LPO BROADWAY Order No. : NEDLANDS WA 6009 Date Sampled : 16-MAY-2008 Date Received : 22-MAY-2008 Attention : Michelle Carey Sampled By : CLIENT Project Name : Your Client Services Manager : Koon-Bay Ho Phone : (08) 9368 8400

Lab Reg No. Sample Ref Sample Description W08/013321 O2A OWEN ANCHORAGE SEDIMENT 16/05/08 W08/013322 O3A OWEN ANCHORAGE SEDIMENT 16/05/08 W08/013323 O5A OWEN ANCHORAGE SEDIMENT 16/05/08 W08/013324 O6A OWEN ANCHORAGE SEDIMENT 16/05/08

Lab Reg No. W08/013321 W08/013322 W08/013323 W08/013324 Sample Reference O2A O3A O5A O6A Units Method Poly Aromatic Hydrocarbons Naphthalene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Acenaphthylene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Acenaphthene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Fluorene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Phenanthrene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Anthracene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Fluoranthene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Pyrene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Benz(a)anthracene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Chrysene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Benzo(b)&(k)fluoranthene mg/kg <0.02 <0.02 <0.02 <0.02 NGCMS_1111 Benzo(a)pyrene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Indeno(1,2,3-cd)pyrene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Dibenz(ah)anthracene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Benzo(ghi)perylene mg/kg <0.01 <0.01 <0.01 <0.01 NGCMS_1111 Organochlorine (OC) Pesticides HCB mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Heptachlor mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Heptachlor epoxide mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Aldrin mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 gamma-BHC (Lindane) mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 alpha-BHC mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 beta-BHC mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 delta-BHC mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 trans-Chlordane mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 cis-Chlordane mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Oxychlordane mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Dieldrin mg/kg <0.001 <0.001 <0.001 <0.001 NR_19

This report is issued in accordance with NATA's accreditation requirements ______P_O_ B_o_x _1_2_46_ _Be_n_tl_e_y _D_C_ W_A_ _6_98_3_ _ T_e_l:_ +_6_1_ _8 _9_3_68_ _8_40_0_ _Fa_x_: _+_6_1_ 8_ 9_3_6_8_ 8_4_9_9 _w_w_w_._m_e_as_u_re_m_e_n_t._go_v_.a_u______N a t i o n a l M e a s u r e m e n t I n s t i t u t e REPORT OF ANALYSIS Page: 2 of 9 Report No. RN685057 Lab Reg No. W08/013321 W08/013322 W08/013323 W08/013324 Sample Reference O2A O3A O5A O6A Units Method Organochlorine (OC) Pesticides pp-DDE mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 pp-DDD mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 pp-DDT mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Endrin mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Endrin Aldehyde mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Endrin Ketone mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 alpha-Endosulfan mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 beta-Endosulfan mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Endosulfan Sulfate mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Methoxychlor mg/kg <0.001 <0.001 <0.001 <0.001 NR_19 Organophosphate (OP) Pesticides Dichlorvos mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Demeton-S-Methyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Diazinon mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Dimethoate mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Chlorpyrifos mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Chlorpyrifos Methyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Malathion mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Fenthion mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Ethion mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Fenitrothion mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Chlorfenvinphos (E) mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Chlorfenvinphos (Z) mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Parathion (Ethyl) mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Parathion Methyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Pirimiphos Methyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Pirimiphos Ethyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Azinphos Methyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Azinphos Ethyl mg/kg <0.01 <0.01 <0.01 <0.01 NR_19 Surrogate Surrogate semivolatile Rec. % 92 92 92 88 Surrogate OC Rec. % 109 138 92 128 NR_19 Surrogate OP Rec. % 117 119 123 129 NR_19 Dates Date extracted 30-MAY-2008 30-MAY-2008 30-MAY-2008 30-MAY-2008 Date analysed 30-MAY-2008 30-MAY-2008 30-MAY-2008 30-MAY-2008

Danny Slee, Section Manager Organics - NSW Accreditation No. 198

20-JUN-2008

Nasir Shikdar, Analyst Inorganics - NSW Accreditation No. 198

20-JUN-2008

Lab Reg No. W08/013321 W08/013322 W08/013323 W08/013324 Sample Reference O2A O3A O5A O6A Units Method Miscellaneous Total Organic Carbon mg/kg 1100 1300 1200 2800 NW_S15

Wei Huang, Analyst Inorganics - NSW Accreditation No. 198

20-JUN-2008

Lab Reg No. W08/013321 W08/013322 W08/013323 W08/013324 Sample Reference O2A O3A O5A O6A Units Method BTEX Benzene mg/kg <0.50 <0.50 <0.50 <0.50 WL230 Toluene mg/kg <0.50 <0.50 <0.50 <0.50 WL230 Ethylbenzene mg/kg <0.50 <0.50 <0.50 <0.50 WL230 Xylene mg/kg <1.0 <1.0 <1.0 <1.0 WL230 Total BTEX mg/kg <2.5 <2.5 <2.5 <2.5 WL230 Miscellaneous Moisture % 11 10 12 15 WL170 Total Petroleum Hydrocarbons TPH C6 - C9 mg/kg <25 <25 <25 <25 WL230 TPH C10 - C14 mg/kg <50 <50 <50 <50 WL230 TPH C15 - C28 mg/kg <100 <100 <100 <100 WL230 TPH C29 - C36 mg/kg <100 <100 <100 <100 WL230

Koon-Bay Ho, Section Manager Organics - WA Accreditation No. 2474

20-JUN-2008

Lab Reg No. W08/013321 W08/013322 W08/013323 W08/013324 Sample Reference O2A O3A O5A O6A Units Method Trace Elements Cadmium mg/kg <1 <1 <1 <1 WL273 Chromium mg/kg 10.4 13.6 13.1 14.1 WL273 Copper mg/kg <1 <1 <1 <1 WL273 Iron mg/kg 430 640 570 590 WL273 Lead mg/kg 1.7 4.8 3.3 3.0 WL273 Magnesium mg/kg 12000 18000 17000 18000 WL273 Manganese mg/kg 10.6 17.3 15.3 15.3 WL273 Mercury mg/kg <0.1 <0.1 <0.1 <0.1 WL41 Nickel mg/kg <1 <1 <1 <1 WL273 Silver mg/kg <1 <1 <1 <1 WL273 Zinc mg/kg 1.6 3.7 2.3 3.1 WL273

David Lynch, Section Manager Inorganics - WA Accreditation No. 2474

20-JUN-2008

Lab Reg No. Sample Ref Sample Description W08/013325 O8A OWEN ANCHORAGE SEDIMENT 16/05/08 W08/013326 O10A OWEN ANCHORAGE SEDIMENT 16/05/08 W08/013327 O13A OWEN ANCHORAGE SEDIMENT 16/05/08

Lab Reg No. W08/013325 W08/013326 W08/013327 Sample Reference O8A O10A O13A Units Method Poly Aromatic Hydrocarbons Naphthalene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Acenaphthylene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Acenaphthene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Fluorene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Phenanthrene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Anthracene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Fluoranthene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Pyrene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Benz(a)anthracene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Chrysene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Benzo(b)&(k)fluoranthene mg/kg <0.02 <0.02 <0.02 NGCMS_1111 Benzo(a)pyrene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Indeno(1,2,3-cd)pyrene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Dibenz(ah)anthracene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Benzo(ghi)perylene mg/kg <0.01 <0.01 <0.01 NGCMS_1111 Organochlorine (OC) Pesticides HCB mg/kg <0.001 <0.001 <0.001 NR_19 Heptachlor mg/kg <0.001 <0.001 <0.001 NR_19 Heptachlor epoxide mg/kg <0.001 <0.001 <0.001 NR_19 Aldrin mg/kg <0.001 <0.001 <0.001 NR_19 gamma-BHC (Lindane) mg/kg <0.001 <0.001 <0.001 NR_19 alpha-BHC mg/kg <0.001 <0.001 <0.001 NR_19 beta-BHC mg/kg <0.001 <0.001 <0.001 NR_19 delta-BHC mg/kg <0.001 <0.001 <0.001 NR_19 trans-Chlordane mg/kg <0.001 <0.001 <0.001 NR_19 cis-Chlordane mg/kg <0.001 <0.001 <0.001 NR_19 Oxychlordane mg/kg <0.001 <0.001 <0.001 NR_19 Dieldrin mg/kg <0.001 <0.001 <0.001 NR_19 pp-DDE mg/kg <0.001 <0.001 <0.001 NR_19

______P_O_ B_o_x _1_2_46_ _Be_n_tl_e_y _D_C_ W_A_ _6_98_3_ _ T_e_l:_ +_6_1_ _8 _9_3_68_ _8_40_0_ _Fa_x_: _+_6_1_ 8_ 9_3_6_8_ 8_4_9_9 _w_w_w_._m_e_as_u_re_m_e_n_t._go_v_.a_u______N a t i o n a l M e a s u r e m e n t I n s t i t u t e REPORT OF ANALYSIS Page: 6 of 9 Report No. RN685057 Lab Reg No. W08/013325 W08/013326 W08/013327 Sample Reference O8A O10A O13A Units Method Organochlorine (OC) Pesticides pp-DDD mg/kg <0.001 <0.001 <0.001 NR_19 pp-DDT mg/kg <0.001 <0.001 <0.001 NR_19 Endrin mg/kg <0.001 <0.001 <0.001 NR_19 Endrin Aldehyde mg/kg <0.001 <0.001 <0.001 NR_19 Endrin Ketone mg/kg <0.001 <0.001 <0.001 NR_19 alpha-Endosulfan mg/kg <0.001 <0.001 <0.001 NR_19 beta-Endosulfan mg/kg <0.001 <0.001 <0.001 NR_19 Endosulfan Sulfate mg/kg <0.001 <0.001 <0.001 NR_19 Methoxychlor mg/kg <0.001 <0.001 <0.001 NR_19 Organophosphate (OP) Pesticides Dichlorvos mg/kg <0.01 <0.01 <0.01 NR_19 Demeton-S-Methyl mg/kg <0.01 <0.01 <0.01 NR_19 Diazinon mg/kg <0.01 <0.01 <0.01 NR_19 Dimethoate mg/kg <0.01 <0.01 <0.01 NR_19 Chlorpyrifos mg/kg <0.01 <0.01 <0.01 NR_19 Chlorpyrifos Methyl mg/kg <0.01 <0.01 <0.01 NR_19 Malathion mg/kg <0.01 <0.01 <0.01 NR_19 Fenthion mg/kg <0.01 <0.01 <0.01 NR_19 Ethion mg/kg <0.01 <0.01 <0.01 NR_19 Fenitrothion mg/kg <0.01 <0.01 <0.01 NR_19 Chlorfenvinphos (E) mg/kg <0.01 <0.01 <0.01 NR_19 Chlorfenvinphos (Z) mg/kg <0.01 <0.01 <0.01 NR_19 Parathion (Ethyl) mg/kg <0.01 <0.01 <0.01 NR_19 Parathion Methyl mg/kg <0.01 <0.01 <0.01 NR_19 Pirimiphos Methyl mg/kg <0.01 <0.01 <0.01 NR_19 Pirimiphos Ethyl mg/kg <0.01 <0.01 <0.01 NR_19 Azinphos Methyl mg/kg <0.01 <0.01 <0.01 NR_19 Azinphos Ethyl mg/kg <0.01 <0.01 <0.01 NR_19 Surrogate Surrogate semivolatile Rec. % 88 89 84 Surrogate OC Rec. % 110 94 94 NR_19 Surrogate OP Rec. % 125 128 119 NR_19 Dates Date extracted 30-MAY-2008 30-MAY-2008 30-MAY-2008 Date analysed 30-MAY-2008 30-MAY-2008 30-MAY-2008

Danny Slee, Section Manager Organics - NSW Accreditation No. 198

20-JUN-2008

Nasir Shikdar, Analyst Inorganics - NSW Accreditation No. 198

20-JUN-2008

Lab Reg No. W08/013325 W08/013326 W08/013327 Sample Reference O8A O10A O13A Units Method Miscellaneous Total Organic Carbon mg/kg 1800 7000 3600 NW_S15

Wei Huang, Analyst Inorganics - NSW Accreditation No. 198

20-JUN-2008

Lab Reg No. W08/013325 W08/013326 W08/013327 Sample Reference O8A O10A O13A Units Method BTEX Benzene mg/kg <0.50 <0.50 <0.50 WL230 Toluene mg/kg <0.50 <0.50 <0.50 WL230 Ethylbenzene mg/kg <0.50 <0.50 <0.50 WL230 Xylene mg/kg <1.0 <1.0 <1.0 WL230 Total BTEX mg/kg <2.5 <2.5 <2.5 WL230 Miscellaneous Moisture % 19 22 21 WL170 Total Petroleum Hydrocarbons TPH C6 - C9 mg/kg <25 <25 <25 WL230 TPH C10 - C14 mg/kg <50 <50 <50 WL230 TPH C15 - C28 mg/kg <100 <100 <100 WL230 TPH C29 - C36 mg/kg <100 <100 <100 WL230

Koon-Bay Ho, Section Manager Organics - WA Accreditation No. 2474

20-JUN-2008

Lab Reg No. W08/013325 W08/013326 W08/013327 Sample Reference O8A O10A O13A Units Method Trace Elements Cadmium mg/kg <1 <1 <1 WL273 Chromium mg/kg 12.7 13.2 13.9 WL273 Copper mg/kg <1 <1 <1 WL273 Iron mg/kg 450 520 630 WL273 Lead mg/kg 2.3 1.8 1.5 WL273 Magnesium mg/kg 17000 15000 19000 WL273 Manganese mg/kg 12.3 13.1 18.5 WL273 Mercury mg/kg <0.1 <0.1 <0.1 WL41 Nickel mg/kg <1 <1 <1 WL273 Silver mg/kg <1 <1 <1 WL273 Zinc mg/kg 3.5 3.1 3.6 WL273

David Lynch, Section Manager Inorganics - WA Accreditation No. 2474

20-JUN-2008

This report is issued in accordance with NATA's accreditation requirements. Accreditated for compliance with ISO/IEC 17025. This report shall not be reproduced except in full. Results relate only to the sample(s) tested.

This Report supersedes reports: RN680951 RN681602 RN682545 RN682846 RN683432

Appendix C

Sand Description (Surface Samples)

LOCALITY 1

Co-ordinates: E 382086 N 6450733

This beach is adjacent the northern edge of Success Bank, a tombolo that extends from the Garden Island - Rottnest dune ridge system in an east-west direction to the mainland. It is the closest locality to the mouth of the Swan River.

Illustrations of beach sand (width of images = 5 mm):

Sample 01A

Position on beach: mid-swash zone

Overall colour: 2.5Y 7/2 light grey

coarse sand, lower class well sorted

Sample 01B

Position on beach: base of primary dune

Overall colour: 2.5Y 7/1 light grey

coarse sand, lower class well sorted

Sample 01C

Position on beach: crest of primary dune

Overall colour: 2.5Y 7/1 light grey

coarse sand, upper class moderately well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 01A 22 3 4 71 514 01B 57 18 7 18 306 01C 58 12 6 24 328 Observations made on dark sand grains: Dark grains comprise 4—7% of the sand, and are almost entirely clasts of limestone. These grains lie along a colour spectrum from white to pale yellow (forming the 3—18% of “light limestone” in the sand) through brownish yellow to grey to black (forming the “dark limestone”). There is often colour variation within a single grain. The dark limestone includes abundant structureless very fine grained limestone and fossil coralline algae, common fossil foraminifera and mollusc fragments (including internal moulds of gastropods), and less common bryozoan and echinoid fossil debris. The fossils, weathered from the parent limestone, are either Representative dark grains in reflected light moulds, or have infilled skeletal cavities (see thin section observations). Width of image: 5 mm The surface of the grains ranges from smooth and highly polished in a few specimens to partially polished with a moderately roungh surface in most Among the modern biogenic grains, some grains are grains. The edges of the grains are rounded. The dark grains react vigor- naturally coloured (mostly yellowish brown, brown, ously with dilute HCl acid, leaving a small amount of residue consisting reddish brown, olive yellow, red — e.g. variously of minute black mineral particles. patterned mollusc shell fragments and echinoid Dark mineralized patches or bands also occur in very rare tests of the spines. modern porcellaneous foraminifera (included under “biogenic grains” in Among the quartz, rare grains have a pale yellow Table). surface stain (“iron oxide stain”).

Fossil foraminifera: Amphisorus hemprichii, Cibicides cf. reﬂugens, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Lamellodiscorbis melbyae, Neorotalia calcar, Pararotalia nipponica, Quinqueloculina bradyana, Q. cf. cuvieriana, Quiqueloculina spp. , Reussella? armata, Textularia sp.

Thin section of sample 01A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 13 %

Observations made on thin section: Under reflected light, the abundant quartz and minor feldspar appear transparent (and very dark reddish brown due to the blue colour of the resin used to mount the slide). Carbonate grains reflect light according to their crystal structure — hyaline carbonate with large-size crystals (compared to the 30 µm thickness of the slide) reflects relatively little light; whereas microgranular carbonate reflects a large amount of light and stands out in the microscope image as dense light coloured grains. In plain transmited light the quartz/feldspar is light and colourless; the hyaline carbonate is transparent to varying degrees with aspects of microstructure apparent; the microgranular carbonate has an opaque dark appearance. Microgranular carbonate forms the structureless limestone grains, and is present infilling many of the large cavities in skeletons (e.g. foraminifera) incorporated in the limestone or eroded from the limestone. Some skeletal cavities are infilled with granular cement (including many of very small cellular cavities in the fossil coralline algae. Dark mineralization is present in 13% of the carbonate grains observed in the thin section. It is in the form of small “patches” — usually with a radiating dendritic structure — within microgranular carbonate. These patches are generally less than 0.1 mm in diameter, but some- times coalesce. In some microgranular carbonate grains the dark patches are distributed throughout the grain, but in others the patches appear to be concentrated parallel to the grain margin. The dark patches appear black and submetallic under reflected light. Among the fossil foraminifera, hyaline walls do not show evidence of mineralization, although dark mineralization does occur in the microgranular carbonate that infills some of the fossil tests. Porcellaneous foraminiferal walls of mostly fossil and some modern, unfilled, shells show the dark mineralization in various degrees. Some of the microgranular carbonate has a diffuse pale yellow to pale brown colour in reflected light. No well developed micritic envelopes around carbonate-grain margins were observed in the section. A few of the mollusc shell fragments exhibit margins which have been bored (probably by cyanobacterial growths) — with bore diameters of about 3 µm and lengths of 50 µm — and have partially micritized margins. LOCALITY 2

Co-ordinates: E 382139 N 6450349

This beach is adjacent Success Bank, a tombolo that extends from the Garden Island - Rottnest dune ridge system in an east-west direction to the mainland.

Illustrations of beach sand (width of images = 5 mm): Sample 02A

Position on beach: mid-swash zone

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class moderately well sorted

Sample 02B

Position on beach: base of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sample 02C

Position on beach: crest of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 02A 23 6 9 61 553 02B 35 26 20 19 339 02C 42 23 13 22 388 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 9—20% of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern Representative dark grains in reflected light skeletal debris forms less than 0.5 % of the sand. Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Cibicides cf. reflugens, Elphidium advenum, E. crispum, E. sp. of Haig 1997, Globorotalia inflata, Lamellodiscorbis melbyae, Neorotalia calcar, Pararotalia nipponica, Peneroplis planatus, Pyrgo striolata, Quinqueloculina bradyana, Q. cf. cuvieriana, Quiqueloculina spp. , Reussella? armata, Rosalina sp. 1, Spiroloculina angulata, Textularia sp. 1, Triloculina tricarinata, T. trigonula

Thin section of sample 02A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 42 %

Observations made on thin section:

The section contains a greater abundance of carbonate grains, including limestone clasts, than does that from locality 1, and a greater proportion of these show the dark mineralized patches described from the locality 1 thin seciton. The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 3

Co-ordinates: E 382178 N 6449797

This beach is adjacent Success Bank, a tombolo that extends from the Garden Island - Rottnest dune ridge system in an east-west direction to the mainland.

Illustrations of beach sand (width of images = 5 mm): Sample 03A

Position on beach: mid-swash zone

Overall colour: 2.5Y 6/1 grey

coarse sand, upper class moderately well sorted

Sample 03B

Position on beach: base of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sample 03C

Position on beach: crest of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 03A 14 11 12 63 555 03B 9 40 31 20 346 03C 18 37 24 21 342 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 12—31% of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern Representative dark grains in reflected light skeletal debris forms less than 0.5 % of the sand. Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Cibicides cf. reflugens, Elphidium advenum, E. crispum, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Pararotalia nipponica, Quinqueloculina bradyana, Quiqueloculina spp., Rosalina sp. 1, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 03A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 48 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 4

Co-ordinates: E 382403 N 6449288

This beach is adjacent the southern edge of Success Bank, a tombolo that extends from the Garden Island - Rottnest dune ridge system in an east-west direction to the mainland.

Illustrations of beach sand (width of images = 5 mm):

Sample 04A

Position on beach: mid-swash zone

Overall colour: 2.5Y 6/1 grey

coarse sand, upper class moderately well sorted

Sample 04B

Position on beach: base of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class moderately well sorted

Sample 04C

Position on beach: crest of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sediment composition: Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 04A 11 20 13 57 520 04B 13 46 26 15 329 04C 12 45 32 11 406 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 13—32% of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern Representative dark grains in reflected light skeletal debris forms less than 0.5 % of the sand. Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Amphistegina lessonii, Cibicides cf. reflugens, Elphidium advenum, E. crispum, Epistomarioides polystomelloides, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Pararotalia nipponica, Peneroplis planatus, Planulinoides biconcavus, Quinqueloculina bradyana, Q. poeyana, Q. subpolygona, Quiqueloculina spp. , Reussella? armata, Sigmamiliolinella australis, Sorites orbicularis, Textularia kerimbaensis, Triloculina trigonula

Thin section of sample 04A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 26 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 5

Co-ordinates: E 382531 N 6448986

This beach faces the northeastern corner of Owen Anchorage.

Illustrations of beach sand (width of images = 5 mm): Sample 05A

Position on beach: mid-swash zone

Overall colour: 2.5Y 6/1 grey

coarse sand, upper class moderately well sorted

Sample 05B

Position on beach: base of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sample 05C

Position on beach: crest of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 05A 8 19 11 62 542 05B 12 40 33 15 339 05C 13 41 31 15 420 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 11—33% of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern Representative dark grains in reflected light skeletal debris forms less than 0.5 % of the sand. Width of image: 5 mm Fossil foraminifera: Cibicides cf. reflugens, Clavulina pacifica, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Glo- bigerinoides quadrilobatus, Lamellodiscorbis melbyae, Neorotalia calcar, Pyrgo compressioblonga, Quinqueloculina bradyana, Quiqueloculina spp., Rosalina sp. 1, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 05A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 35%

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 6

Co-ordinates: E 382684 N 6448534

This beach faces the northeastern corner of Owen Anchorage.

Illustrations of beach sand (width of images = 5 mm): Sample 06A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class moderately well sorted

Sample 06B

Position on beach: base of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sample 06C

Position on beach: crest of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sediment composition: Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 06A 18 18 13 51 547 06B 11 45 23 21 359 06C 15 42 21 22 306 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 13-23 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern Representative dark grains in reflected light skeletal debris forms less than 0.5 % of the sand. Width of image: 5 mm Fossil foraminifera: Cibicides cf. reflugens, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Globorotalia inflata, Lamel- lodiscorbis melbyae, Pararotalia nipponica, Peneroplis planatus, Quinqueloculina poeyana, Quiqueloculina spp., Spiroloculina subimpressa, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 06A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 30 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 7 Co-ordinates: E 383273 N 6446921 This beach faces the eastern side of Owen Anchorage. Illustrations of beach sand (width of images = 5 mm): Sample 07A

Position on beach: mid-swash zone

Overall colour: 2.5Y 7/2 light grey

coarse sand moderately well sorted

Sample 07B

Position on beach: base of primary dune

Overall colour: 2.5Y 6/1 grey

coarse sand, lower class well sorted

Sample 07C

Position on beach: crest of primary dune

Overall colour: 2.5Y 7/2 light grey

coarse sand, lower class well sorted

Sample 07D

Position on beach: in secondary dune

Overall colour: 2.5Y 7/2 light grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 07A 13 2 2 83 764 07B 36 14 6 44 348 07C 36 8 4 52 397 07D 20 4 3 73 317 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 2-6 % of the sediment, and are responsible for the overall light grey colour of the sand. The grains appear slightly darker when wet than when dry.

Fossil foraminifera: Amphisorus hemprichii, Amphistegina lessonii, Cibicides cf. reflugens, Clavulina pacifica, Elphidium advenum, E. novozealandicum, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Neoconorbina sp., Pararotalia nipponica, Penerop- lis planatus, Quinqueloculina bradyana, Q. poeyana, Q. polygona, Quiqueloculina spp., Reussella? armata, Rotorbis auberi, Spiroloculina subimpressa, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 07A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 10%

Observations made on thin section: The grain types and the style of dark mineralization observed here are the same as at locality 1. LOCALITY 8

Co-ordinates: E 383268 N 6446391

This beach faces the eastern part of Owen Anchorage.

Illustrations of beach sand (width of images = 5 mm): Sample 08A

Position on beach: mid-swash zone

Overall colour: 2.5Y 7/2 light grey

medium sand, upper class moderately well sorted

Sample 08B

Position on beach: base of primary dune

Overall colour: 2.5Y 7/2 light grey

coarse sand, lower class moderately well sorted

Sample 08C

Position on beach: crest of primary dune

Overall colour: 2.5Y 7/2 light grey

medium sand, upper class moderately well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 08A 21 4 3 72 571 08B 39 10 3 51 304 08C 33 9 2 56 428 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 2-3 % of the sediment, and are responsible for the overall light grey colour of the sand. The grains appear slightly darker when wet than when dry.

Fossil foraminifera: Amphisorus hemprichii, Cibicides cf. reﬂugens, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Globorotalia inﬂata, Lamellodiscorbis melbyae, Neorotalia calcar, Pararotalia nipponica, Peneroplis planatus, Quinquelocu- lina bradyana, Q. cf. cuvieriana, Quiqueloculina spp., Rotorbis auberi, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 08A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 12%

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 9

Co-ordinates: E 383171 N 6445725

This beach faces the eastern part of Owen Anchorage.

Illustrations of beach sand (width of images = 5 mm): Sample 09A

Position on beach: mid-swash zone

Overall colour: 2.5Y 7/2 light grey

medium sand, upper class well sorted

Sample 09B

Position on beach: base of primary dune

Overall colour: 2.5Y 7/2 light grey

medium sand, upper class well sorted

Sample 09C

Position on beach:

Overall colour: 2.5Y 7/2 light grey

medium sand, upper class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 09A 17 6 3 74 584 09B 23 19 6 52 373 09C 22 25 5 48 354 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 3-6 % of the sediment, and are responsible for the overall light grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Cibicides cf. reflugens, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Globorotalia inflata, Heter- ostegina depressa, Lamellodiscorbis melbyae, Pararotalia nipponica, Peneroplis planatus, Pyrgo compressioblonga, Quinquelo- culina bradyana, Quiqueloculina spp., Reussella? armata, Rosalina sp. 1, Spiroloculina subimpressa, Triloculina striatotrigonula

Thin section of sample 09A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 23%

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 10

Co-ordinates: E 382938 N 6445022

This beach faces the southeast part of Owen Anchorage.

Illustrations of beach sand (width of images = 5 mm): Sample 10A

Position on beach: mid-swash zone

Overall colour: 2.5Y 6/2 light brownish grey

coarse sand, upper class well sorted

Sample 10B

Position on beach: base of primary dune

Overall colour: 2.5Y 6/2 light brownish grey

coarse sand, upper class well sorted

Sample 10C

Position on beach: crest of primary dune

Overall colour: 2.5Y 6/2 light brownish grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 10A 15 10 7 68 702 10B 14 41 15 30 312 10C 18 36 7 39 531 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 7-15 % of the sediment, and are responsible for the overall light brownish grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Cibicides cf. reflugens, Elphidium advenum, E. crispum, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Pararotalia nipponica, Peneroplis planatus, Planulinoides biconcavus, Quinqueloculina polygona, Quiqueloculina spp., Reussella? armata, Rosalina sp. 1, Sahulia sp. 1, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 10A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 19%

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. As observed in reﬂected light, much of the microgranular carbonate forming the limestone (and inﬁlling cavities in fossils) has a diffuse pale brown colour. LOCALITY 11

Co-ordinates: E382463 N 6444384

This beach faces the southeast corner of Owen Anchorage and lies on the promontory that forms Woodman Point (continuous with the “Parmelia Bank” tombolo).

Illustrations of beach sand (width of images = 5 mm): Sample 11A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class moderately well sorted

Sample 11B

Position on beach: base of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sample 11C

Position on beach: crest of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 11A 7 13 11 69 525 11B 5 42 16 36 300 11C 6 36 18 39 357 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 11-18 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Cibicides cf. reflugens, Clavulina pacifica, Elphidium advenum, E. crispum, E. novozealandicum, Gaudryina convexa, Globoro- talia inflata, Lamellodiscorbis melbyae, Neoconorbina sp., Pararotalia nipponica, Peneroplis planatus, Planoglabratella opercularis, Quiqueloculina spp., Reussella? armata, Textularia kerimbaensis, T. cushmani, Triloculina tricarinata

Thin section of sample 11A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 38 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 12

Co-ordinates: E 382162 N 6444184

This beach faces the southeastern part of Owen Anchorage and lies on the promontory that forms Woodman Point (continuous with the “Parmelia Bank” tombolo).

Illustrations of beach sand (width of images = 5 mm): Sample 12A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class moderately well sorted

Sample12B

Position on beach: back of beach

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

A primary dune is not present at this locality.

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 12A 3 32 16 50 372 12B 2 22 15 60 603 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 15-16 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Amphistegina lessonii, Cibicides cf. reflugens, Clavulina pacifica, Elphidium advenum, E. crispum, Epistomarioides polystomelloides, Gaudryina convexa, Lamellodiscorbis melbyae, Pararotalia nipponica, Peneroplis planatus, Planoglabratella opercularis, Quinqueloculina polygona, Quiqueloculina spp., Reussella? armata, Rosalina sp. 1, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 12B:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 49 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 13

Co-ordinates: E 381823 N 6444089

This beach faces the southeastern part of Owen Anchorage and lies on the promontory that forms Woodman Point (continuous with the “Parmelia Bank” tombolo).

Illustrations of beach sand (width of images = 5 mm): Sample 13A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sample13B

Position on beach: back of beach

Overall colour: 2.5Y 5/1 grey

medium sand, upper class well sorted

A primary dune is not present at this locality.

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 13A 2 37 21 40 327 13B 3 56 23 18 511 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 21-23 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Cibicides cf. reflugens, Cibicoides basilanensis, Elphidium advenum, E. crispum, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Pseudomassilina australis, Quiqueloculina spp., Rosalina sp. 1, Triloculina striatotrigonula, T. tricarinata

Thin section of sample 13B:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 55 %

Observations made on thin section: The section contains the highest percent found among the carbonate grains, of particles with dark mineralization. The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY 14

Co-ordinates: E 381363 N 6443979

This beach faces the southeastern part of Owen Anchorage and lies on the promontory that forms Woodman Point (continuous with the “Parmelia Bank” tombolo).

Illustrations of beach sand (width of images = 5 mm): Sample 14A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class modeerately well sorted

Sample 14B

Position on beach: at base of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class well sorted

Sample 14C

Position on beach: at crest of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar 14A 1 56 18 25 322 14B 4 59 15 22 545 14C 1 54 14 31 302 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 14-18 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Baggina sp., Cibicides cf. reflugens, Elphidium advenum, E. crispum, novozealandicum, Gaudryina convexa, Globigerinoides sp., Globorotalia inflata, Lamellodiscorbis melbyae, Neoconorbina sp., Neogloboquadrina sp., Pararo- talia nipponica, Peneroplis planatus, Planoglabratella opercularis, Quinqueloculina polygona, Quiqueloculina spp., Reussella? armata, Rosalina sp. 1, Textularia kerimbaensis, Triloculina striatotrigonula

Thin section of sample 14B:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 46 %

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. LOCALITY B1

Co-ordinates: E 379302 N 6417887

This beach faces the southeastern part of Wanbro Sound and lies on the promontory that forms Becher Point Point (continuous with a tombolo connecting this point and the Garden Island-Rottnest dune-ridge system).

Illustrations of beach sand (width of images = 5 mm): Sample B1A

Position on beach: mid-swash zone

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class moderately well sorted

Sample B1B

Position on beach: base of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, upper class well sorted

Sample B1C

Position on beach: crest of primary dune

Overall colour: 2.5Y 5/1 grey

coarse sand, lower class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar B1A 8 24 15 53 433 B1B 7 36 22 35 535 B1C 8 38 14 39 385 Observations made on dark sand grains: The dark grains in this sample are almost entirely limestone fragments with the same characteristics as those at locality 1.

Dark limestone clasts form 14-22 % of the sediment, and are responsible for the overall grey colour of the sand. The grains appear slightly darker when wet than when dry.

As at locality 1, very rare tests of the modern porcellaneous foraminifera have dark mineralized patches or bands. Naturally coloured modern skeletal debris forms less than 0.5 % of the sand. Representative dark grains in reflected light Width of image: 5 mm Fossil foraminifera: Amphisorus hemprichii, Amphistegina lessonii, Cibicides cf. reflugens, Clavulina pacifica, Elphidium advenum, E. novozealandicum, Gaudryina convexa, Globorotalia inflata, Lamellodiscorbis melbyae, Neoconorbina sp., Pararotalia nipponica, Penerop- lis planatus, Quinqueloculina bradyana, Q. poeyana, Q. polygona, Quiqueloculina spp., Reussella? armata, Rotorbis auberi, Spiroloculina subimpressa, Textularia kerimbaensis, Triloculina striatotrigonula, T. tricarinata

Thin section of sample B1B:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 50%

Observations made on thin section: The grain types and the style of dark mineralization are the same as at locality 1. Rare yellowish-red argillaceous limonitic grains are present. LOCALITY C1

Co-ordinates: E 381997 N 6459428

This beach faces the open Rottnest shelf at a latitude just north of where, on the mid and outer shelf, the Garden Island - Rottnest dune-ridge system swings into an east-west orientation.

Illustrations of beach sand (width of images = 5 mm): Sample C1A

Position on beach: mid swash zone

Overall colour: 2.5Y 7/3 pale yellow

coarse sand, lower class well sorted

Sample C1B

Position on beach: base of primary dune

Overall colour: 2.5Y 8/2 pale yellow

medium sand, upper class well sorted

Sample C1C

Position on beach: 2.5Y 8/2 pale yellow

Overall colour: 2.5Y 8/2 pale yellow

medium sand, upper class well sorted

Sediment composition (%): Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar C1A 87 10 <1 3 315 C1B 74 10 <1 15 505 C1C 65 17 <1 18 205 Observations made on dark sand grains: Dark grains are very rare and include some dark limestone and also very rare dark coloured “heavy minerals”. Many of the “light” limestone grains present in the sand are pale yellow, as are some of the modern skeletal fragments.

Fossil foraminifera: No identiﬁable fossil foraminifera were observed.

Thin section of sample C1B:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 12 %

Observations made on thin section: The microgranular carbonate inﬁlling rare fossil bryozoa and gastropods and the tests of some modern porcellaneous foraminifera have scattered minute patches of dark mineralization as described for grains from locality 1. Some of the grains have a diffuse pale yellow colour. LOCALITY C2

Co-ordinates: E 382910 N 6431509

This beach, south of Woodman Point, faces the deep-water basin of Cockburn Sound.

Illustrations of beach sand (width of images = 5 mm): Sample C2A

Position on beach: mid-swash zone

Overall colour: 2.5Y 7/4 pale yellow

coarse sand, upper class moderately well sorted

Sample C2B

Position on beach: base of primary dune

Overall colour: 2.5Y 7/3 pale yellow

coarse sand, lower class moderately well sorted

Sample C2C

Position on beach: crest of primary dune

Overall colour: 2.5Y 7/3 pale yellow

coarse sand, lower class moderately well sorted

Sediment composition: Sample quartz/minor feld- light limestone dark limestone biogenic grains Total grain count spar C2A 18 2 1 80 537 C2B 19 18 2 61 247 C2C 28 10 2 61 378 Observations made on dark sand grains: Dark grains are very rare. Much of the modern skeletal material is stained pale yellow, and the “light” limestone is usually pale yellow-brown. Most of the limestone grains are structureless and very ﬁne grained.

Fossil foraminifera: No identiﬁable fossil foraminifera were observed.

Thin section of sample C2A:

Thin section viewed under transmitted light Same view under reﬂected light Width of image: 5 mm Width of image: 5 mm

Carbonate grains — % with dark mineralization (based on 100 carbonate grain count in thin section viewed under re- ﬂected light (using x20 objective lens): 12 %

Observations made on thin section: The limestone grains consist of microgranular carbonate which has a pale yellow colour. Rare yellowish-red argillaceous limonitic grains are present. The rare dark mineraalization in the microgranular carbonate is similar to that at locality 1.