In the Kyläniemi Area, SE Finland

Working Report 2013-12

Subglacial Hydrology of the Lake District Ice Lobe During the Younger Dryas (ca. 12 500–11 600 years ago) in the Kyläniemi Area, SE Finland

Juha Pekka Lunkka Kari Moisio Anna Vainio

University of Oulu

July 2013

Working Reports contain information on work in progress or pending completion.

The conclusions and viewpoints presented in the report are those of author(s) and do not necessarily coincide with those of Posiva.

ABSTRACT

It is essential to gain knowledge on the subglacial hydrological conditions at the glacier bed / bedrock interface when assessing how bedrock fracture zones affect subglacial melt water flow and in which subglacial zones pressurized and oxygen-rich melt water penetrates into the bedrock fracture systems. In the warm-based glacier zones, a part of subglacial melt water will penetrate deep into the fracture systems although the major part of melt water is drained to and beyond the ice margin via subglacial tunnel networks especially in the areas where ice is flowing on the crystalline bedrock. During the last deglaciation phase of the former Scandinavian Ice Sheet, glaciofluvial accumulations were deposited and these sediment accumulations are highly important when picturing the subglacial hydrology of different ice streams during deglaciation in the crystalline bedrock area.

The aim of the present work was to map the bedrock fracture zones in the Kyläniemi area and to shed light on the subglacial hydrology of the Scandinavian Ice Sheet’s Lake District Ice Stream that occupied the Kyläniemi area during the Younger Dryas between ca. 12 500 – 11 600 years ago. The special emphasis within this general aim was to study the relationship between bedrock fracture zones and the routes of subglacial drainage paths.

The methods used to map and study bedrock fracture zones and subglacial drainage paths included remotes sensing methods, field observations, ground penetrating radar (GPR) investigations and GIS-based reconstructions. Conventional geological field methods aided by the GPR-method were also used to map bedrock exposures and their structures and to define the type of glaciofluvial sediments and glaciofluvial landform associations.

Two main fracture zone sets occur in the study area. The most prominent bedrock fracture zone set trends NW-SE while the other, less prominent fracture zone set is aligned in NE-SW direction. The majority of the minor joint sets in the study area also strike parallel to the trend of these two major fracture zone sets and the dip of the joint planes is almost vertical. The results of three dimensional joint pattern observations indicate that joint systems represent sheet joints where joint spacing is moderate or low. The landform association and sediment architecture of glaciofluvial formations in the study area show that glaciofluvial accumulations are composed of longitudinal eskers, glaciofluvial ice-contact deltas and ice-contact sub-aquatic fans. During the Younger Dryas when the ice front started to retreat, subglacial melt water drainage occurred via tunnel networks that developed close to the terminus of the Lake District Ice Stream. An analysis of the esker paths and their relationship with fracture zones indicates that in the southern Saimaa Basin, located in the area between the First and the Second Salpausselkä, subglacial melt water tunnels followed the flanks of major NW-SE and N- S oriented fracture zones. However, on the proximal side of the Second Salpausselkä, topographic depression i.e. fracture zones did not entirely govern the development of the subglacial tunnel systems. The most probable reason for this is that in the southern Saimaa Basin the ice front terminated in deeper water than on the proximal side of the Second Salpausselkä. Due to the difference in water depth in front of the ice margin in these two areas, the ice surface gradient was steeper north of the Second Salpausselkä

area compared to the ice surface gradient that developed in the southern Saimaa Basin. Since water flow in ice is governed by bedrock topography and the ice surface gradient, the bedrock topography affected the subglacial melt water flow more in the southern Saimaa Basin than on the proximal side of the Second Salpausselkä where melt water flow was largely governed by the ice surface profile.

Keywords: Bedrock fracture zones, joint sets, glaciofluvial deposits, glacial hydrology, GIS-reconstruction, Lake District Ice Stream, southern Saimaa Basin, Salpausselkä end moraines, Younger Dryas.

Järvi-Suomen kielekevirran jäänalainen hydrologia nuoremman Dryas- kauden aikana (12 500- 11 600 vuotta sitten) Kylänniemen alueella, Kaakkois-Suomessa

TIIVISTELMÄ

On olennaista tuntea jäätikön hydrologiset olosuhteet arvioitaessa jäätikön pohjaosissa olevien paineellisten sulavesien tunkeutumispotentiaalia kallioperän heikkousvyöhyk- keitä pitkin syvemmälle kallioperän rakosysteemeihin. Varsinkin lämminpohjaisilla mannerjäätikön vyöhykkeillä osa sulavesistä tunkeutuu kallioperän rakosysteemeihin, mutta suurin osa sulavesistä kanavoituu etenkin kiteisillä kallioperäalueilla kallioperän ja jään pohjan välisiin subglasiaalisiin tunneleihin ja tunneliverkostoihin, joiden kautta subglasiaaliset sulavedet purkautuvat jäätikön reunan ulkopuolelle. Muinaisen Skan- dinavian mannerjäätikön sulamisvaiheen aikana jäätikön sulavesien kerrostamat glasifluviaaliset maaperämuodot ovat tärkeitä indikaattoreita muinaisen mannerjäätikön hydrologiasta, ja niiden avulla on mahdollista saada tietoa eri jäätikkövirtausten subglasiaalisesta hydrologiasta viimeisen deglasiaatiovaiheen aikana.

Tämän työn tarkoituksena oli kartoittaa Kyläniemen tutkimusalueella, Kaakkois-Suo- messa kallioperän pääruhjevyöhykkeet ja rakosysteemit sekä määrittää tutkimusalueella sijainneen, muinaiseen Skandinavian mannerjäätikköön kuuluneen Järvi-Suomen kielekevirran subglasiaalinen hydrologia Nuoremman Dryas-kauden aikana ja etenkin alueella esiintyneet subglasiaaliset sulavesitunnelit ja niiden suhde kallioperän ruhjevyöhyk- keisiin.

Kallioperän ruhjevyöhykkeiden paikantamisessa ja glasifluviaalisten maaperäassosiaa- tioiden tutkimuksessa käytettiin hyväksi kaukokartoitusmenetelmiä ja GIS-pohjaisia rekostruktiomenetelmiä. Kaukokartoitustulokset varmennettiin geologisin kenttähavain- noin ja maatutkaluotauksin. Kallioperän rakoilututkimukset tehtiin koventionaalisia kenttätutkimusmenetelmiä käyttäen kalliopaljastumilta. Lisäksi rakoilututkimuksissa käytetiin hyväksi maatutkaluotausta.

Tutkimusalueen kallioperän pääruhjesuuntia on kaksi. Ruhjevyöhykkeistä erottuu sel- vemmin luode-kaakko suuntaisten ruhjeiden parvi. Tämän pääruhjesuunnan lisäksi useat ruhjeet ovat suuntautuneet lounaasta koilliseen. Tutkimusalueen kallioperän rako- parvet ovat valtaosaltaan suuntautuneet siten, että niiden kulku yhtyy pääruhjesuuntien kulkuun ja niiden kaade on useimmiten verrattain pysty. Rakojen kolmiulotteisen kartoituksen perusteella yleisin rakotyyppi alueella on laattarakoilu, jossa rakotiheys oli kohtalainen (0,3 – 1 m) tai alhainen (> 1m). Tutkimusalueella glasifluviaaliset muodostumat ovat pitkittäisharjuja, deltoja ja alkiodeltoja. Glasifluviaalisten muodostumien assosiaatiot tutkimusalueella osittavat, että pääosa muinaisen mannerjäätikön subglasiaalisesta vedestä kanavoitui subglasiaalisiin tunneleihin Järvi-Suomen kielekevirran reunavyöhykkeessä. Salpausselkien välisellä vyöhykkeellä Etelä-Saimaan altaassa subglasiaalisten sulavesien kulkua ohjasi alustan topografia ja subglasiaalinen sula- vesitoiminta keskittyi luoteesta kaakkoon ja pohjoisesta etelään kulkeviin pääruhjeisiin. Toisen Salpausselän proksimaalipuolella alustan topografia ei ohjannut merkittävästi sulavesien kulkua ja sulavesitunnelit eivät sijoittuneet kallioperän pääruhjevyö- hykkeiden alueelle. Todennäköisin syy subglasiaalisten sulavesien erilaiseen jakautu-

miseen näiden kahden alueen välillä on se, että jäätikön reuna päättyi syvempään veteen Etelä-Saimaan alueella, kun taas Toisen Salpausselän pohjoispuolella jään reuna päättyi hyvin matalaan veteen tai maalle. Veden syvyys jäätikön reunan edessä on toden- näköisesti vaikuttanut jäätikön pintaprofiiliin. Pienempi jään pintagradientti eli loivempi jään pintaprofiili Etelä-Saimaan alueella vaikutti todennäköisesti siihen, että kallioperän topografia ohjasi sulavesien kulkeutumista tehokkaasti, kun taas toisen Salpausselän pohjoispuolisilla alueilla jään pintagradientti oli suurempi ja subglasiaalista sulavesien kulku ei ollut niin riippuvainen kallioperän topografiasta vaan jäätikön pinnnan profiilista.

Avainsanat: Ruhjevyöhykkeet, rakoilu, glasifluviaaliset muodostumat, jäätikön hydrologia, GIS-rekonstruktio, Järvi-Suomen kielekevirta, Etelä-Saimaan allas, Salpausselät, Nuorempi Dryas-kausi.

TABLE OF CONTENTS

ABSTRACT

TIIVISTELMÄ

1 INTRODUCTION ...... 3

2 MATERIAL AND METHODS ...... 7 2.1 Data sources ...... 7 2.2 Field methods ...... 7 2.2.1 Geological field observations ...... 7 2.2.2 Geophysical methods ...... 9 2.3 GIS methods and data processing ...... 10

3 STUDY AREA ...... 11

4 RESULTS ...... 15 4.1 Bedrock fracture zones in the study area ...... 15 4.2 Observations on bedrock, joint structures and their patterns ...... 17 4.3 Subglacial melt water paths and their relationship to bedrock fracture zones .. 19

5 DISCUSSION AND CONCLUSION ...... 21

REFERENCES ...... 27

APPENDIX I – Bedrock exposure observations from the kyläniemi study sites ...... 29

APPENDIX 2 – Summery table of geological observations of joint structures and bedrock types at the sites studied ...... 61

1 INTRODUCTION

During the Late Weichselian deglaciation phase (a time period between ca. 18 000 to 10 000 years ago), the eastern flank of the Scandinavian Ice Sheet (SIS) was divided into ice dome areas and active ice streams (Figure 1). The ice dome areas were situated in the centre of the ice sheet in the Scandinavian mountain range while the ice streams in the eastern flank of the SIS were discharging ice from the dome areas to the ice terminus (Boulton et al. 2001). Based on glacial landform associations and knowledge on ice sheet’s dynamics, it seems evident that the behaviour of the ice streams in the eastern flank of the SIS was very complex (cf. Boulton et al. 2001, Putkinen and Lunkka 2008). The ice streams behaved in a semi-independent manner in time and space, but their detailed configuration and time-transgressive behaviour are not fully known for the whole of the SIS over the entire length of the last deglaciation.

During the Younger Dryas chronozone (c. 12 800 – 11 600 calendar years ago), which was a cold stadial period that lasted for more than 1000 years, the retreat of the ice sheets stopped and ice sheets advanced or remained stationary worldwide. At that time, the ice front of the SIS was situated in southern Finland (Figure 1). Based on chronological studies, the First and the Second Salpausselkä end moraine ridges in southern Finland mark the ice terminus and were deposited between 12 800 – 11 500 years ago i.e. during the Younger Dryas Stadial (Tschudi et al. 2000, Saarnisto and Saarinen 2001, Rinterknecht et al. 2006).

Figure 1. Deglaciation chronology, ice marginal isolines and ice stream (arrows) and ice lobe patterns of the eastern flank of the SIS between 18 000 and 11 000 years ago after Svendsen et al. (2004). Salpausselkä I and II end moraines were deposited between ca. 12 800 to 11 500 years ago.

The ice stream and ice lobe pattern for the eastern flank of the SIS during the Younger Dryas Stadial has been reconstructed using the glacial landform association approach linked with sedimentological observations (cf. Punkari 1980, Fyfe 1990, Palmu 1998, Boulton et al. 2001, Svendsen et al. 2004). Based on these reconstructions, the ice streams and associated ice lobes that existed in southern Finland included the Baltic Sea Ice Stream, the Lake District Ice Stream and the North Karelian Ice Stream (Figure 2). Two of these ice streams (the Baltic Ice Stream and the Lake District Ice Stream) terminated in the Baltic Ice Lake that existed in front of the ice margin while the North Karelian Ice Stream terminated on land. It has been shown that during the deposition of the Second Salpausselkä, the terminus of the Lake District Ice Lobe stood in the Baltic Ice Lake that was in most parts less than 50 meters deep (Lunkka and Erikkilä 2012). Recent investigation on the water level history in front of the Lake District Ice Lobe during and after the Younger Dryas suggests that as the ice margin stood at the Salpausselkä zone, the water level regressed in the southern Saimaa Lake Basin first from the highest Baltic Ice Lake BI-level to BII-level and from BII-level to g-level. Subsequently, there was a rapid transgression in the southern Saimaa Basin when the water level transgressed ca. 15 metres from g-level to the Baltic Ice Lake BIII-level (Lunkka and Erikkilä 2012). After the ca. 15-metre regression from level BIII to the Yoldia Sea level YI, the southern Saimaa area became isolated from the Yoldia Sea.

According to Saarnisto and Saarinen (2001), the water level drop took place at around 11 700 years ago when the Second Salpausselkä had already been deposited. In addition to these water level changes, Pajunen (2005) has also suggested that there was an extremely low water level stand in the Lower Saimaa area at around 11 000 C-14 cal. BP ago when the outlet threshold of the Lower Saimaa Lake was situated at Kyläniemi.

Figure 2. Ice lobe configuration in Finland during the last deglaciation after Johansson et al. (2011).

The subglacial hydrology of the ice streams of SIS in its eastern flank during and after the Younger Dryas stadial is virtually unknown although changing hydrological conditions must have played a major role in the behaviour of the ice streams (cf. Paterson 1991). Theoretically, melt water in subglacial setting can drain via the following mechanisms: 1) bulk movement within deforming subglacial debris, 2) Darcian porewater flow, 3) pipe flow, 4) dendritic channel network flow, 5) linked cavity, 6) braided channel network or 7) water film at the ice bedrock interface (e.g. Benn & Evans 1998). Since the volume of melt water produced into the subglacial environment is the greatest during deglaciation, it is extremely important to understand the drainage system pattern beneath the ice and the factors that govern the melt water drainage during increased melt water production. Melt water drainage via Darcian porewater and pipe flow mechanisms as well as drainage via deforming subglacial strata and the braided channel network system are the main drainage systems that operate in the areas where a thick subglacial sediment or a sedimentary rock cover occurs. In the

large scale, drainage patterns on crystalline bedrock areas are confined to the dendritic channel network flow, linked cavity and water film systems. In the crystalline bedrock areas, the subglacial drainage system that will develop at the ice/bedrock interface during deglaciation is mainly dependent on the pressure conditions under ice. The pressure conditions proximal to the ice grounding line are mainly dependent on the ice slope profile and the bedrock topography. While the ice slope profile in the marginal zone of ice streams is dependent on the water depth in front of the ice margin, bedrock fracture zones are the main structures that influence the local topography. By studying glaciofluvial deposits and their genesis, landform associations and their spatial distribution, it is possible to shed light on the nature of the subglacial hydrology that prevailed during deglaciation and to depict the continuity of the drainage systems under ice.

Lunkka & Erikkilä (2012) studied the palaeoenvironments that existed in front of the Lake District Ice Lobe in the Salpausselkä zone and defined the water depth in front of the Lake District Ice Lobe during the Younger Dryas. Based on their observations, it was assumed that the water depth in front of the ice grounding line had only a minor influence on the ice surface profile and pressure conditions under ice. However, troughs ca. 100 meters deep in front of the Second Salpausselkä in Kyläniemi for example, may have had a local influence on the ice surface profile and the distribution of melt water drainage paths under ice.

In the present study, the principal aim is to make a reconstruction of hydrological conditions that existed beneath the Lake District Ice Stream of the Scandinavian Ice Sheet in the Kyläniemi area during and immediately after the Younger Dryas (ca. 12 500 – 11 700 years ago). In order to achieve this general aim, the purpose of the study is to investigate and map subglacial melt water drainage paths and to define the relationship between the melt water drainage systems and large and small scale bedrock structures in the area next to the Salpausselkä end moraine ridges. This information is highly crucial when modelling the ice sheet’s potential to inject pressurized and oxygen-rich melt water into the crystalline bedrock aquifers via fracture zones during the time when wet-based ice remains stationary in one place, like the Salpausselkä zone, over several hundreds of years.

2 MATERIAL AND METHODS

2.1 Data sources

The material used to study the subglacial hydrology of the former Lake District Ice Stream/Lobe system and its relationship with bedrock structures in the study area includes the following data sources:

- 1:200 000 scale digital map of the Quaternary deposits (Geological Survey of Finland 2011 a). These maps were used to study large scale landform associations and the nature of glaciofluvial sedimentation patterns.

- 1:20 000 scale digital and printed edition of basic topographic maps (National Land Survey of Finland 2011a). These maps were used to create a detailed interpretation of glaciofluvial landforms, such as esker types and paths and the occurrence of glaciofluvial deltas, sub-aquatic fans and sandurs in the study area. - LIDAR (Light Detection and Ranging) digital elevation model (DEM) imageries (National Land Survey of Finland 2011b) were available only of the eastern part of the study area. LIDAR imageries were used to aid detailed interpretation of fracture zones and eskers/deltaic deposits in the areas where LIDAR data was available.

- 1:200 000 scale digital geological bedrock map (Geological Survey of Finland 2011b), which covers the entire study area. However, there are no structural observations on bedrock features shown on these digital maps. It should also be noted that the bedrock map of the area covered by Lake Saimaa is only schematic due to the lack of observation points in areas covered by lakes.

- 1:100 000 scale printed edition of the geological bedrock map of Finland, sheet 3134-Lappeenranta, which is the only geological bedrock map of the study area in which structural features (mainly strikes and dips of bedrock lineation) are presented (Geological Survey of Finland 1964).

- Digital elevation model (DEM, 25 x 25 m) (National Land Survey of Finland 2011a) for the identification of fracture zones, their orientation and dimensions in the study area.

2.2 Field methods

2.2.1 Geological field observations

Geological field observations were done in June and August 2012. The aim of field work was to map 1) the location of eskers and other glaciofluvial deposits in the study area and to map 2) bedrock types and bedrock structures on small islands in Lake Saimaa and onshore around Kyläniemi.

Geological field observations of glaciofluvial deposits targeted on checking the preliminary interpretation carried out using remote sensing (see data sources chapter 2.1) on the location of glaciofluvial formations, as well as the types of eskers and glaciofluvial systems such as glaciofluvial deltas, sub-aquatic fans and sandurs trains. After these observations, the sites for the Ground Penetrating Radar (GPR) investigations were selected.

Bedrock observations were taken in the field in order to picture how large and small bedrock discontinuities, i.e. fractures and joints, occur in the study area. A detailed study of jointing was conducted around Kyläniemi where bedrock observations were done on the proximal and distal sides of the Second Salpausselkä end moraine. Field investigations were targeted on presently low lying areas close to the Lake Saimaa water level where the bedrock topography is relatively flat. After a comprehensive investigation of islands around the Kyläniemi area, detailed geological observations were taken on 13 small islands and on 3 sites located on mainland. A total amount of 29 different bedrock exposures at16 different study sites were investigated.

At the bedrock exposures, the following information was collected: 1) GPS-location of the site and dimensions of the exposed bedrock area. 2) Rock type(s) at the exposure. 3) Joint patterns on the bedrock surface. These measurements include: a) strike and dip of the joint plane sets, b) joint spacing termed here as joint frequency. 4) Direction of glacially formed striations.

In addition to these observations, GPR-measurements were carried out at the exposures where a clear joint pattern was observed and where the topography was gentle enough for GPR-measurements.

By definition, joints are regular arrangements of fractures in rock masses along which there has been little or no movement. In the present study, joint sets were categorized as the main joint sets and the secondary joint sets. The main joint plane set at each rock exposure was defined based on the joint frequency (i.e. spacing) of individual joints with the same or almost the same attitude (strike and dip). The main joint set at the exposure is the joint set where the joint planes with more or less the same attitude (strike and dip) are closely spaced and where the joint sets are the most pronounced. Other joint sets with a longer joint spacing than in the main joint set were defined as secondary joint sets. The attitude of joint planes was measured by defining the strike and the dip (degrees) of the joint planes. Ice flow direction was measured from striations on bedrock exposures when encountered. The direction of ice flow and the joint planes (strike/dip) were both measured using a geological compass with a clinometer (Suunto GEO-5). The measurements of the joint planes were plotted on the equal area Wulff net using Openstereo 0.1.2. devel programme. In addition, the frequency (spacing) of the joints was measured and the following terminology was applied to characterize joint frequency in the joint sets (see Appendix 2). Depending on their frequency, the joint sets were termed as:

Low frequency sets (LFS) – individual joints in the joint set were on average > 1 m apart.

Moderate frequency sets (MFS) – individual joints in the joint set were on average 0.3 – 1 m apart.

High frequency sets (HFS) – individual joints in the joint set were on average 0.1 – 0.3 m apart.

Dense frequency sets (DFS) - individual joints in the joint set were on average < 0.1 m apart.

2.2.2 Geophysical methods

Ground Penetrating Radar (GPR) technique was used to examine objects or interfaces in the shallow sub-surface of the earth (cf. Hänninen 1991, Maijala 1991). The GPR equipment consists of an antenna, a central processing unit (CPU), power supply, a computer for recording the measurements, GPS positioning equipment and a travel- wheel that calculates the distance of the measured GPR lines in the field (Hänninen, 1991). The GPR antenna has two main components; a transmitter and a receiver. The GPR method is based on the behaviour of an electric pulse in material. GPR transmits electromagnetic [VHF (Very high frequency) or UHF (Ultra high frequency)] waves into the sub-surface. Some of this energy is reflected back from the electrical boundaries and the two-way travel time in nanoseconds and the amplitude of the reflections are recorded (Smith & Jol 1997). The electrical boundaries that will be recorded in a GPR profile represent the interfaces of different geological materials that have different dielectrical properties. Different dielectrical properties in sediments are mainly the result of changes in water content and lithology while reflections from crystalline bedrock are usually related to weathering surfaces, fractures and different lithologies. The detailed physical background for the GPR method is given e.g. by Annan & Davies (1976).

The GPR-technique was mainly used in the present work to study the homogeneity of bedrock at selected bedrock outcrops and to investigate the internal structure of glaciofluvial systems. In the bedrock outcrops the GPR-method was also used to test the method’s ability to detect the dimensions of bedrock joints and to get information on the depth and size of the joints and their frequency. The GPR data obtained together with geological observations helped to assess the overall nature of bedrock homogeneity at the bedrock outcrops. The GPR antenna was placed directly on the bedrock surface and pulled by hand. The pulling direction was perpendicular to the visually observed main or secondary joint plane set direction in the bedrock. GPR was also used to detect architectonic elements of glaciofluvial sediments in the study area in order to reveal the subglacial drainage patterns adjacent to glaciofluvial deltas and sub-aquatic fans. When investigating glaciofluvial deposits, the antenna was on roads pulled by car and off-road by hand.

GPR investigations were carried out in the Kyläniemi area with 50 MHz, 100 MHz and 250 MHz antennae. The antennae used to examine bedrock outcrops were MALÅ Geoscienses shielded RAMAC antennae with 100 MHz and 250 MHz frequencies. The

antennae were used separately. The antennae used to examine glaciofluvial deposits were MALÅ Geosciences unshielded Ramac cable antenna (Rough Terrain Antenna, RTA) with 50 MHz frequency and MALÅ Geoscienses shielded RAMAC antenna with 100 MHz frequency. The antennae were used simultaneously or the 100 MHz antenna was used alone. The CPU used as the main control unit was MALÅ Geosciences Professional Explorer (ProEx) System. Distances were measured with MALÅ Geosciencies travel-wheel and GPS positioning was performed with Garmin GPSMap 62st.

The obtained GPR data were processed with ReflexWin program (version 6.0.9). All the GPR data were subjected to the following preprocessing stages before the GPR imageries were analyzed: 1) 1-D filtering with a subtract-DC-shift and subtract-mean (dewow), 2) signal gaining, 3) static correction for shifting the beginning of the signals to the top of the profile (0-axis) and 4) background removal. In addition, a topographic correction was performed to the GPR lines when appropriate.

2.3 GIS methods and data processing

GIS methods were used in the present work to create a reconstruction of the bedrock fracture zones and their relationship with glaciofluvial sediments in the study area. All observations made in the field from glaciofluvial deposits and bedrock structures, including joint mapping of bedrock exposures, were digitally stored in the database and the data compiled were processed with ArcMap 10.1-programme.

Fracture zones were analyzed and their location digitized with Arc Map 10.1. The Digital Elevation Model (DEM), Laser scanning (LAS-LIDAR), and bathymetric and topographic maps (National Land Survey of Finland 2011a, b) were used as the basic source of information for the interpretation of bedrock fracture zones in the study area.

Larger fracture zones were analyzed and their location digitized as shape files on 1:150 000 to 1:400 000 scale DEM maps while smaller scale fracture zones were identified from 1:150 000 – 1:20 000 scale DEM maps. The interpretation of fracture zones in areas covered by lakes was based on interpreting the digitized bathymetric maps (Liikennevirasto 2011) with steep elevation gradients considered to indicate the location of fracture zones. The orientation and length of all fracture zones are presented on DEM maps.

Glacial deposits in the study area were interpreted from the digitized topographic maps and Quaternary maps (digitized 1:200 000 scale map and printed 1:100 000 scale map of Quaternary Deposits Sheet 3134 Lappeenranta). Remote sensing interpretations were checked in the field after which the type and location of glaciofluvial deposits were digitized as shape files on DEM and LIDAR-LAS maps. Similarly, the coordinates of the GPR metadata were imported from each GPR line to create an excel-file and processed to correct form for the Arc Map programme. After that, the location of each GPR line was digitized with Arc Map and displayed on digitized topographic maps.

3 STUDY AREA

The study area is located in the southern Saimaa Basin around Kyläniemi, southeastern Finland, where the Finnish Lake District Ice Lobe was located during the Younger Dryas deglaciation phase (Figure 3). The area studied extends from the proximal side of the First Salpausselkä end moraine in Imatra-Taipalsaari area to the south to the proximal side of the Second Salpausselkä as far as the south of Puumala area (Figure 4). The special emphasis within this area was to study the area around Kyläniemi. Most of the study area is covered by lakes and inland waterways (Figure 3) with the topography ranging from the Saimaa lake level ca. 76 metres above sea level (asl) to 180 metres asl in the northeastern part of the study area.

Figure 3. Map of the area covered by the former Lake District Ice Stream (LDIS) of the Scandinavian Ice Sheet. The major glaciofluvial accumulations (green) shown on the map were deposited by the LDIS. Lakes and the main towns in the area are also indicated. SsI = First Salpausselkä end moraine; SsII = Second Salpausselkä end moraine. The study area is located around Kyläniemi (The National Land Survey of Finland 2011a, Geological Survey of Finland 2011c).

Figure 4. Location of the study area around Kyläniemi.

Bedrock in the study area belongs to Svecofennian supracrustal rocks that occur between the Archean craton in the north, Rapakivi area in the south and Central Finland granitoid complex in the west (Lehtinen et al. 1998). The bedrock of the Saimaa area mostly consists of metamorphic rocks such as gneisses and migmatites. In addition, volcanites and late orogenic granites as well as black schists also occur in the area. As seen from the geological map of the study area, gneiss and granitic rocks (granodiorite, tonalite, enderbite) are the most common bedrock types in the Kyläniemi area (Figure 5).

Figure 5. Bedrock in the study area (Geological Survey of Finland, 2011b).

Quaternary clastic sediments in the study area consist of till, sand and gravel as well as fine sediments. Till was mostly deposited as cover moraine, drumlins and drumlinoids. Glaciofluvial sediments occur as eskers and end-moraines (glaciofluvial deltas and subaquatic fans). The most prominent Quaternary deposits in the study area are the First and Second Salpausselkä end moraines that run through the study area in SW-NE direction (see Figures 3 and 6). Other glaciofluvial deposits include the esker ridges that run into the Salpausselkä end moraines broadly from the northwest (see Figures 3 and 6). There are large areas in the southern and northern parts of the Salpausselkä zone where barren bedrock and bedrock covered by a thin cover of loose sediments occur. The zone north of Salpausselkä II, in particular, is mainly void of a thick Quaternary cover.

Figure 6. Quaternary map of the study area (digital data Geological Survey of Finland 2011c). The study area extends from the First Salpausselkä end moraine in the SE to the Puumala area in the NW.

4 RESULTS

4.1 Bedrock fracture zones in the study area

The main fracture zones in the study area are shown in Figure 7. It has to be stressed here that a thorough interpretation of bedrock fractures in Lake Saimaa was very difficult with the methods applied in this work. Therefore, bedrock fracture data from the bottom of Lake Saimaa are very sparse and only the most imminent fracture zones were interpreted based on bathymetric data and aeromagnetic maps. The main fracture zones shown in Figure 7 are the main structural elements in the bedrock that dictate the topography of the study area. The main fracture zones defined from DEM data are mainly oriented NW-SE direction although there is also a slight maximum in NE-SW direction (Figure 8). In addition to the larger fracture zones, a large number of smaller bedrock fractures occur throughout the study area (Figure 9). The orientation of the smaller fractures is dominantly parallel or sub-parallel to the orientation of the main fracture zones but there are also minor bedrock fractures that are perpendicular to the associated main bedrock fractures (Figure 9). The lower hemisphere rose diagram showing the directions of all the fracture zones indicates a preferred NW-SE orientation of fractures zones in the study area (Figure 10).

The main fracture zones cut through granite, granodiorite and mica paragneiss bedrock areas in the Kyläniemi study area (see Figure 7). However, some major fractures, and more often minor fractures, are aligned along the bedrock boundaries especially between granodiorite/granite and gneiss bedrock (see Figure 9).

Figure 7. Bedrock map of Saimaa area with the main fracture zones (black lines) identified in the study area (black square). For bedrock colour codes, see Figure 5.

Figure 8. Lower hemisphere rose diagram showing the orientation (trend) of the main fracture zones in the study area.

Figure 9. Bedrock map with the major and minor bedrock fracture zones (black lines) in the study area (black square) interpreted from DEM data, aeromagnetic maps and field investigations.

Figure 10. Lower hemisphere rose diagram showing the orientation (trend) of all the fracture zones in the study area.

4.2 Observations on bedrock, joint structures and their patterns

Observations on joint structures and their patterns were taken at 29 selected exposures (for detailed descriptions see Appendix I) that were mainly located on islands on the proximal and distal sides of the Second Salpausselkä end moraine in the Kyläniemi area (Figure 11). The sites investigated are situated next to the present lake Saimaa water level. Bedrock around Kyläniemi where most of the sites are located is composed of granite, mica gneiss (biotite paragneiss) and granodiorite. Joints were abundant at almost every exposure investigated (see Appendices I and II). Joint plane measurements at the studied exposures indicate that there are two almost vertical and perpendicular joint sets, which have been developed in granite and mica gneiss bedrock (Figure 12).

Surface observations and GPR data suggest that three sets of tensional joints are normally well developed in granite and granodiorite bedrock exposures, with two joint sets almost vertical and perpendicular to each other, and one more or less horizontal. The joint sets can be categorized as sheet joints and the jointing pattern is roughly parallel to the bedrock surface. In addition, at some exposures where bedrock is mica gneiss the joint sets occasionally follow the foliation in gneiss. The direction of the main joint plane set (i.e. the most prominent joint set with the densest joint spacing) varies from one exposure to another (Figure 13) but the main joint directions of NW-SE and NE-SW seem to be well developed around the Kyläniemi area. The joint sets are aligned along the same direction as the main fracture zones in the study area.

Figure 11. Location of 18 study sites around Kyläniemi where bedrock type and joint patterns were investigated at 29 bedrock exposures.

Figure 12. Equal area lower hemisphere plot (poles to planes) of joint planes measured in the study area. Results indicate two almost vertical and perpendicular major joint sets that dictate the joint pattern in the study area.

Figure 13. The attitude (strike and dip) of the main joint plane sets in the study area.

4.3 Subglacial melt water paths and their relationship to bedrock fracture zones

A total of eleven major longitudinal esker systems representing subglacial melt water drainage paths of the former Lake District Ice Stream occur between the First and the Second Salpausselkä end moraines (Figure 14). It has to be noted that in the Saimaa Lake Basin only the most evident melt water drainage paths were possible to map. Based on remote sensing and field investigations in the area between the First and Second Salpausselkä end moraines, the major and minor fracture zones in the study area are oriented NW-SE (Figure 14). In addition to this main direction, there are two major and several minor fracture zones oriented SW-NE, and a number of both major and minor bedrock fractures trending N-S (Figure 14).

The direction of eskers (i.e. former subglacial melt water tunnels) between the First and the Second Salpausselkä end moraines follows more or less the trend of the main NW – SE bedrock fracture orientation, which was also the ice movement direction during the last deglaciation. However, there are eskers that trend from north to south in the eastern part of the study area between the Salpausselkä end moraines. These eskers clearly follow the local fracture zones that also trend approximately from north to south. Esker ridges in all fracture zones in the area are preferably located on the flanks of bedrock fracture zones but not at the bottom of these topographic depressions. This indicates that the hydraulic gradients along which subglacial melt water flowed were not governed solely by bedrock topography but also by the ice surface profile.

On the proximal side of the Second Salpausselkä, there are also eleven major longitudinal esker systems. The feeding esker systems that terminate in the Second Salpausselkä deltas are well developed on the proximal side of the end moraine. There are a total of 31 identified subglacial tunnels in the study area, which released melt water and sediment to and beyond the ice grounding line and deposited the Second Salpausselkä. The major fracture zones proximal to the Second Salpausselkä are not all aligned in NW-SE direction but there are a number of major bedrock fractures oriented SW-NE and N-S and some NNE-SSW (Figure 14). On the proximal side of the Second Salpausselkä, minor bedrock fractures are mostly trend ing NE-SW and N-S. However, the orientation of the minor fracture zones is highly dispersed in the area (see Figures 14 and 15).

The direction of eskers in the northern part of the study area proximal to the Second Salpausselkä end moraine is mostly trending from the NNW to the SSE although in the Puumala area two major esker systems are aligned from the north to the south. Based on a detailed analysis of the melt water drainage paths indicated by the trend of esker ridge core elements, it seems evident that the majority of subglacial melt water tunnels crossed the major bedrock fracture zones in the study area. This implies that the major bedrock fractures (i.e bedrock topography) did not influence the melt water drainage under ice. However, sub-glacial melt water tunnels close to the contemporary ice grounding line i.e. close to the Second Salpausselkä deltas, and esker deltas/sub-aquatic fans proximal to the Second Salpausselkä were locally influenced by minor bedrock fractures (i.e. topographical lows) (Figure 15).

5 DISCUSSION AND CONCLUSION

The bedrock fracture zones mapped in the study area are mostly trending NW-SE but there is also a great number of fault zones that are oriented perpendicularly to the main NW-SE fracture trend. Detailed measurements of joint sets in the area around Kyläniemi show the same directional trends as larger bedrock fracture zones in the whole of the study area. This indicates that most of the minor joint set patterns studied and the formation of the major and minor fracture zones are genetically linked, and most probably related to the larger scale tectonic movements in the Laatokka-Perämeri zone during and after the Neoproterozoic.

Figure 14. Map of the major and minor bedrock fracture zones and their relationship to the direction of eskers (i.e. subglacial melt water drainage paths) in the study area.

Glacial melt water systems are in the study area mainly represented by longitudinal esker ridges, glaciofluvial sub-aquatic fans and glaciofluvial deltas. Esker ridges and sub-aquatic fans and to some extent glaciofluvial deltas have later been affected by shore processes during transgressive and regressive phases in the Saimaa Basin. The primary glaciofluvial accumulations are quite continuous and abundant in the study area. Based on remote sensing and field observations on the occurrence of esker deltas,

breaks in sedimentation and glaciofluvial erosional features along the longitudinal esker routes, the estimated length of the melt water tunnels operating under ice in time and place ranged from just one kilometre to up to 10 kilometres. However, subglacial tunnels under ice could have been much longer in some areas but their true nature is not possible to define through interpretation of glacial geomorphological features alone.

Figure 15. Map of minor bedrock fracture zones and their relationship to the direction of eskers (i.e. subglacial melt water drainage paths) in the northern part of the study area.

During the course of the last deglaciation, the First and Second Salpauselkä ridges in south-east Finland that mark the termini of the Lake District Ice Lobe were deposited during the Younger Dryas stadial between ca. 12 500 to 11 700 years ago as deltas or subaquatic fans (e.g. Lunkka et al. 2004). As discussed by Lunkka and Erikkilä (2012), the water depth of the Baltic Ice Lake (BI-stage) in front of the Lake District Ice Lobe was generally less than 40 metres as the ice front was situated in the position that is at present marked by the First Salpausselkä (Figure 16). Based on remote sensing data (location and altitude), analyzed glaciofluvial landform association (i.e. relationship between esker ridges, deltas and sub-aquatic fans) and ice movement indicator data, it was possible to reconstruct the ice marginal isolines for the study area (Figure 17). As the ice retreated from the First Salpausselkä across the southern Saimaa Basin,

subglacial melt water drainage systems (eskers) formed diachronously and the NW-SE and N-S trends of these systems followed and were partially governed by the bedrock fracture zones i.e. bedrock topography. The slightly curved pattern of the ice marginal isolines in Figure 17 might reflect the fact that in the southern Saimaa Basin, proximal to the First Salpausselkä the ice front terminated in deeper water. This implies that the ice surface gradient was more gentle compared to areas where the ice front terminated in shallow water or on land.

Figure 16. Reconstruction of the Lake Disrict Ice Lobe and the bathymetry of the Baltic Ice Lake at around 12 300 – 12 500 years ago when the Baltic Ice Lake stood at B I- level (digital data © Maanmittauslaitos 2011b, Baltic GIS 2011).

Figure 17. Ice marginal isolines (i.e. contemporaneous positions of the ice margin) in the study area during the last deglaciation. Ice marginal isolines are shown as white lines.

Lunkka and Erikkilä (2012) suggested that when the Second Salpausselkä in Kyläniemi was deposited the water level of the Baltic Ice Lake was ca. 15 metres (at present ca. 93 m asl) lower than during the subsequent BIII-stage of the Baltic Ice Lake (at present ca. 108 m asl). After this transgression to the BIII-level, the water level dropped in the Baltic Basin by ca. 28 metres to the contemporary sea level. The water level drop from the Baltic Ice Lake BIII level to the Yoldia Sea YI-level led to the isolation of the southern Saimaa Lake Basin from the Yoldia Sea. During this event, the water level dropped in the southern Saimaa Basin by only ca. 13 metres (cf. Saarnisto 1970).

Subglacial meltwater systems on the proximal side of the Second Salpausselkä were thus formed during the time when the ice margin terminated in shallow water or on land. The approximate water depth in front of the ice margin was in many areas less than ca. 20 metres. Based on the results presented above, it is evident that subglacial melt water systems cross the bedrock fracture zones on the proximal side of the Second Salpausselkä. This indicates that the local ice surface gradient was steeper than at the time when the ice margin was located in the southern Saimaa Basin between the First Salpausselkä and the Second Salpausselkä.

Overall, the water flow direction in the subglacial melt water tunnels (i.e. longitudinal eskers) follows paths perpendicular to the hydraulic equipotential surfaces in the ice (cf. Shreve (1972, 1985). As shown by e.g. Shreve (1972), the hydraulic equipotential surfaces dip up-glacier with a gradient that is 11 times as great as the down-glacier ice surface gradient. This indicates that in the southern Saimaa Basin the bedrock topography had a greater effect on the development of the subglacial melt water drainage pattern compared to the subglacial drainage systems that developed in the area north of the Second Salpausselkä. The reason for this difference is partially the fact that due to the difference in water depth in front of the ice margin, the ice surface gradient was steeper north of the Second Salpausselkä area compared to the ice surface gradient that developed in the southern Saimaa Basin.

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APPENDIX I – Bedrock Exposure Observations from the Kyläniemi Study Sites

Talsionsaari

Talsionsaari is located south-east of Kyläniemi (Figure 1). Four exposures were studied on the western side of Talsionsaari and one (Exposure 5) in the southeastern part of the island (Figure 1).

Figure 1. Location of the exposures studied on Talsionsaari, south-east of Kyläniemi

Exposure 1 - Selkäniemi (6793925 N and 564635 E). The exposure 1 is 21 metres long and 24 metres wide. The shore is relatively steep with the bedrock rising 1.8 metres above the lake level at 10 metres' distance. The bedrock is composed of pegmatite granite. There is one main joint set visible with a strike of 340° dipping 85° towards the west. The frequency of the joints is moderate, 0.5 m on average. A minor joint set was also observed in the exposure with a strike of 250° and dip 85° towards the south, joint frequency being moderate to low, 1 metre on average.

Three different GPR lines (lines TA1, TA2 and TA4) were investigated at Exposure 1 (Figure 2). The lines were measured with a 100 MHz antenna. Line TA1 is 20 metres long, line TA2 is 13 metres long and line TA4 is 11 metres long. Clear reflections were only gained from the upper 10 metres of the bedrock (Figure 3). Reflections are not clearly visible below that level. The vertical joints visible on the bedrock surface were not possible to identify in the GPR images but there is a clear sub-horizontal joint pattern in all three GPR-images, which most probably indicates sheet joints that are cut by almost vertical joint sets.

Figure 2. Location of the GPR-lines at Exposure 1 on Talsionsaari. Blue arrow heads indicate the pulling direction.

Figure 3. 100 MHz GPR profiles of investigation lines A) TA1, B) TA2 and C) TA4. Green lines indicate the main joint planes within the upper part of the bedrock.

Exposure 2 – (6794937 N, 564128 E) The exposure is approximately 27 metres long and 20 metres wide. The shore profile is steep. The bedrock rises approximately 1.8 meters above the lake level at 3 metres' distance. The bedrock is migmatite composed of mica gneiss and granite inclusions and veins. Three different joint set directions were observed at Exposure 2. The average strike of the main joint planes is 160° dipping 50°-90° towards the E. Joint frequency ranges from 0.05 m to 2 m, and is moderate overall. Joints are tight. The dip of the secondary joint plane sets observed is also almost vertical (75° - 90° mainly towards the N) with average strike directions 060° and 105°.

Exposure 3 – (6794581 N, 564513 E) The exposure located on the western side of the island (see Figure 1) is 10 metres long and 10 metres wide. The shore profile is gentle and the bedrock rises approximately 1 to 2 metres above the lake level at 10 metres' distance. The bedrock is composed of migmatite with granite veins. Two separate joint sets were observed. The average strike of the joint planes in the main joint set is 350° dipping 75° towards the west. Joint frequency ranges from 0.1 m to 1 m, mostly from 0.1 m to 0.4 m. The minor joint plane set strikes 080° dipping 80° towards the NNE where joint plane frequency is between 1.5 – 2.0 metres.

Exposure 4 – (6794527 N, 564549 E) Exposure 4 is located on the western side of Talsionsaari (Figure 1). The exposure is approximately 40 metres long and 30 metres wide. The shore is relatively gentle with the bedrock rising approximately 4.3 metres above the lake level at 22 metres' distance. The bedrock is composed of migmatite that includes granite/granodiorite veins and inclusions of mica gneiss.

The main joint planes observed strike 330° dipping 85° towards the SW. The joint frequency in the main joint set is moderate to low i.e. 0.5 m to 2 m. The secondary joint set attitude is 220° striking with almost a vertical dip (87° - 90°) towards the east, and the joint frequency is low (from 3 m to 12 m).

Three GPR lines were made at Exposure 4 on Talsionsaari (Figure 4). Lines TA6 and TA7 were measured with a 250 MHz antenna and line TA8 with a 100 MHz antenna. Line TA6 is 12 metres, line TA7 19 metres and line TA8 39 metres long. All three lines were measured from west to east. The radar images show horizontal and sub-horizontal joint patterns down to 13 metres (Figures 5 and 6).

Figure 4. Location of GPR lines (TA6, TA7, TA8) at Exposure 4 on Talsionsaari.

Figure 5. 250 MHz GPR profiles of investigation lines A) TA6 and B) TA7. Green lines indicate the main weakness and joint sets within the upper part of the bedrock down to ca. 10 - 13 m depth.

Figure 6. 100 MHz GPR profile of line TA8. Green lines indicate the main weakness and joint sets within the upper part of the bedrock down to ca. 12 m depth.

Exposure 5 – (6794154 N, 565363 E) Exposure 5 is approximately 18 metres long and 16 metres wide. The shore profile is relatively gentle with the bedrock rising ca. 1.8 metres above the lake level at 12 metres' distance. The bedrock is composed of pegmatite granite containing inclusions of mica gneiss (1 m to 6 m wide on the surface). Two different joint sets occur on the surface exposure. The main joint plain set strikes 145° dipping 85° towards the NE. The joint frequency is low, from 2 m to 4 m. The secondary joint plain set strikes 055° dipping 85° towards the NW.

Kyläniemi, Susiniemi Exposure 1 - (6794793 N, 563627 E) The bedrock exposure on shore Kyläniemi at Susiniemi is flat, ca. 10 metres wide and 40 metres long next to the lake (Figure 7). The exposure is located at the junction of granodiorite and pegmatite granite and the bedrock is on the site composed of granite/granodiorite with quartz veins and only few mica gneiss inclusions. There were virtually no fractures/joint sets visible on the bedrock surface. One almost vertical N-S trending joint and one almost vertical E-W trending joint were recorded at the exposure.

Figure 7. Location of exposed bedrock along the eastern side of Susiniemi.

Figure 8. Bedrock exposure on the eastern side of Susiniemi.

Suuri Mäntysaari

Suuri Mäntysaari is an island located ca. 4 kilometres NW of Kyläniemi. Four bedrock exposures were studied on the island (Figure 9).

Figure 9. Location of bedrock exposures studied on Suuri Mäntysaari.

Exposure 1- (6797543 N, 556588 E) Exposure 1 is located on the southeastern side of Suuri Mäntysaari (Figure 9). The shore profile is very steep and therefore unsuitable for GPR measurements and drilling operations. The bedrock is composed of pegmatite granite.

Exposure 2 - (6797341 N, 555957 E) Exposure 2 is located on the southern side of Suuri Mäntysaari (Figure 9). Exposure 2 is 28 metres long and 20 metres wide. The shore is gentle. The bedrock rises 1.8 metres above the lake level at 25 metres' distance. The bedrock is composed of pegmatite granite containing feldspar- and quartz veins. The main joint plane direction is striking between 010° to 040° and dipping between 70° to 80° towards the NNW. Joint frequency ranges between 0.4 - 2 m. The secondary joint planes strike between 325°and 340° dipping 85° to 90° towards the SW. Joint frequency ranges from 0.1 metres to 5 m, and is most commonly over 0.5 metres.

Exposure 3 - (6797368 N, 556040 E) Exposure 3 is located on the southern side of Suuri Mäntysaari next to Exposure 2 (Figure 9). The exposure is approximately 28 metres long and 20 metres wide. The shore is gentle. The bedrock rises 1.8 metres above the lake level at 20 metres' distance. The bedrock is composed of coarse pegmatite granite with inclusions of mica gneiss. The main joint plane set strikes between 310° to 345° dipping between 60° to 90° towards the SW. Joint frequency ranges from 5 cm to 3 m (0.5 m on average). The secondary joint plane set strikes between 270° to 300° dipping 80° towards the south. Joint frequency is in the secondary joint plane set very low ranging from 1m to 2 m.

Exposure 4 - (6798043 N, 556306 E) Exposure 4 is located on the northern side of Suuri Mäntysaari (Figure 9). This exposure is 30 metres long and 7 metres wide. The shore is gentle. The bedrock rises only 1 metre above the lake level at 7 metres' distance. The bedrock is composed of pegmatite granite. The main joint plane set strikes 200° to 240° dipping 60° towards the SSE. The secondary joint plane set strikes 120° dipping 80° towards the NE. In addition, there is also a minor joint plane set that strikes 050° dipping 80° towards the NE. The joint frequency of the main joint plane set ranges from 0.1m to 1 m, and in other joint plane sets the frequency is approximately 0.5 metres or less.

Two GPR lines (lines SM1 and SM2) were made on Suuri Mäntysaari (Figure 10). Line SM1 was measured with a 250 MHz antenna and SM2 with a 100 MHz antenna. Line SM1 at Exposure 2 is 11 metres long (Figure 11) and Line SM2 at Exposure 3 is 28 metres long (Figure 11).

Figure 10. Location of two GPR lines investigated at exposures 2 and 3 on Suuri Mäntysaari. Line SM 1 and Line SM2 were measured from west to east as indicated with blue arrow heads.

Figure 11. Two GPR profiles of subsurface joint structures on Suuri Mäntysaari: A) Line SM1 (250 MHz antenna) at Exposure 2 and B) Line SM2 (100 MHz antenna) at Exposure 3. Green lines indicate the main weakness zones and joint sets within the upper ca. 12 m of the bedrock.

Paskaluoto

Paskaluoto is located ca. 0.5 kilometers north of Kyläniemi (Figure 12). Two bedrock exposures were investigated on the island (Figure 12).

Figure 12. Location of Paskaluoto next to the Kyläniemi Peninsula.

Exposure 1 - (6797115 N, 558284 E) Exposure 1 on the eastern side of Paskaluoto is 30 metres long and 7 metres wide (Figure 13). The shore is relatively gentle. The bedrock rises 1.8 metres above the lake level at 7.5 metres' distance. The bedrock is composed of pegmatite granite with mica gneiss inclusions. The strike and dip of foliation in mica gneiss is striking 240° and dipping 40° towards the SE. There is one weakly developed joint plane set in pegmatite granite that strikes 135° and dips 70° towards the NE. Joint frequency is low in pegmatite granite with individual joint planes 0.5 m to 1 m apart.

Figure 13. Location of two bedrock exposures investigated on Paskaluoto.

Exposure 2 - (6797112 N, 558211 E) The exposure on the western side of Paskaluoto is 27 metres long and 16 metres wide (Figure 14). The shore profile is relatively gentle. The bedrock rises 1.8 metres above the lake level at 11 metres' distance. The bedrock is composed of coarse-grained pegmatite granite with 0.2 m – 1 m wide veins of mica gneiss. The main joint planes follow the bedrock lineation with an average strike of 220° and dip 40° towards the SE. The frequency of the joint planes ranges from 0.5 m to 2m.

A 26-metre long GPR line (Line P2) was investigated on Paskaluoto (Figure 15). Line P2 was measured with a 250 MHz antenna from the SE to the NW, perpendicular to the main joint plane direction. Strong hyperbolic and sub-horihorizontal reflections penetrate down to 8 metres (Figure 15) indicating vertical and horizontal bedrock jointing.

Figure 14. Location of GPR line P on Paskaluoto.

Figure 15. GPR profile of Line P2 (250 MHz antenna) showing hyperbolic and sub- horizontal reflections from the main weakness zones and fault planes down to ca. 8 metres. Green lines indicate the interpreted joint planes.

Hietasaari

Exposure 1 – (6800069 N, 559101 E) Hietasaari is an island ca 1.5 kilometres long and 800 metres wide, located on the western side of Kyläniemi (Figure 16). The bedrock is composed of granite and mica gneiss. Exposure 1 was studied in the northeastern part of Hietasaari (Figure 17).

Figure 16. Location of Hietasaari island west of Kyläniemi.

Figure 17. Location of Exposure 1 on the northwestern shore of Hietasaari.

Exposure 1, from the NW to the SE, is 130 metres long and 10 metres wide. The shore is quite gentle. The bedrock rises 1.8 metres above the lake level at 9 metres' distance. The NW part of the shore is composed of mica gneiss including pegmatite granite veins. In the middle part of Exposure 1, the bedrock is granite with inclusions of mica gneiss (40 cm -1 m wide veins) while in the SE part of the exposure the bedrock is composed of mica gneiss with granitic dykes. The main joint plane set strikes 265°- 270° dipping 85° towards south. Joint frequency ranges from 0.4m to 3 m. The secondary joint plane set strikes 020° dipping 75° towards the west and joint frequency is low, over 1 m. The bedrock foliation in mica gneiss strikes 180° dipping 75° to 80° towards the east.

Ojatsunsaari

Ojatsunsaari is located next to Kyläniemi (Figure 18) and two bedrock exposures were studied there (Figure 19).

Exposure 1 - (6800896 N, 562082 E) Exposure 1 is located on the northeastern side of Ojatsunsaari (Figure 19). The exposure is 10 metres long and 15 metres wide. The shore profile is gentle. The bedrock rises 1.8 metres above the lake level at 15 metres' distance. The bedrock is composed of pegmatite granite with one inclusion of mica gneiss. The main joint plane set strikes 020° dipping 70°-80° towards the W. Joint frequency ranges from 0.4 m to 2 m. The secondary joint plane set in the exposure strikes 060°dipping 80° towards the NW. Joint frequency is low, over 1 m on average. The bedrock lineation measured in mica gneiss strikes 130° dipping 75° towards the NE.

Figure 18. Location of Ojatsunsaari north of Kyläniemi.

Exposure 2 - (6800899 N, 562041 E) Exposure 2 is located on the northeastern side of Ojatsunsaari (Figure 19). The exposure is 17 metres long and 15 metres wide. The shore is gentle. The bedrock rises 1.8 metres above the lake level at 15 metres' distance. The bedrock is composed of pegmatite granite with inclusions of mica gneiss. The main joint plane set strikes 280° dipping 75° towards the S. Joint frequency ranges between 1 m – 10 m.

Figure 19. Location of two bedrock exposures studied on Ojatsunsaari.

Soukkioniemi

Soukkioniemi is a peninsula on the NE side of Kyläniemi and one bedrock exposure was studied there (Figure 20).

Exposure 1 - (6799921 N, 560769 E) Exposure 1 is 75 metres long and 11 metres wide. The shore is gentle. The bedrock rises 1.8 meters above the lake level at 12 metres' distance. In the eastern part of the shore (6799917 N, 560850 E), the bedrock is composed of mica gneiss. In the middle part of the exposure, the bedrock is more granitic and in western part of the exposure (6799921 N, 560769 E), the bedrock is composed of mica gneiss with granitic dykes with quartz and feldspar veins. The main joint plain set strikes 080° dipping 85° towards the N. Joint frequency ranges between 0.1 m – 1 m. The secondary joint plane set, which is well developed in the western part of the exposure, strikes 140° dipping 75° towards the NE. Joint frequency ranges between 2-3 metres. The foliation in mica gneiss strikes 170° dipping 60° towards the east.

Figure 20. Location of Exposure 1 in Soukkioniemi.

Korkiatsaaret North

Korkiasaaret North is an island located southeast of Kyläniemi (Figure 21). The bedrock rises ca. 12 metres above the Lake Saimaa level to the centre of the island. The shores of the island range from flat to quite steep. The bedrock is composed of granite and pegmatite granite, both containing mica gneiss inclusions. Two bedrock exposures next to the lake shore were studied (Figure 22).

Figure 21. Location of Korkiatsaaret North south east of Kyläniemi.

Exposure 1 - (6795654 N, 564948 E) Exposure 1 was studied on the south-west side of Korkiatsaaret North (Figure 22). The exposure is 16 metres long and 11 metres wide. The shore is flat. The bedrock rises only some decimetres above the lake level. The bedrock is composed of granite and inclusions/veins of mica gneiss (2.5 metres x 4 metres) that also contain pegmatite dykes (1 cm – 10 cm wide on the surface). The main joint plane direction in the bedrock is striking 060° with dips 80° up to 90° towards the NW. The frequency of the joint planes on the surface of the exposure is between 0.2 m and 1 m being 0.5 m on average. The joint planes in the secondary joint set strike 90° dipping 80°-90° towards the north where the frequency of the joint planes is 0.5 m on average. The bedrock foliation measured in mica gneiss is striking 220° and dipping 40° towards the SE.

Exposure 2 - (6795655 N, 564990 E) Exposure 2 is located on the southern side of Korkiatsaaret North (Figure 22). The exposure is 49 metres long and 27 metres wide. The shore is quite steep. The bedrock rises 4.3 metres above the lake level at 22 metres' distance. In NE part of the exposure (6795665 N, 565009 E), the bedrock is composed of granite. In the middle part of the exposure, the bedrock is composed of pegmatite granite with inclusions of mica gneiss (20 cm and 1-2 m wide). In the SW part of the exposure (6795649 N, 564970 E), the bedrock is composed of granite. The main joint plane set strikes 320-330° dipping 85° towards the SW. Joint plane frequency in the main joint set ranges from 0.1 m to 3 m. The joint planes in the secondary joint set strike 230° dipping 85° towards the SE. The frequency of the joint planes is 2.5 m on average.

Figure 22. Location of two bedrock exposures studied on Korkiatsaaret North. The perpendicular attitudes of the main joint plane sets are also indicated.

Värrötsaaret South

Värrötsaaret South is an island ca. 200 metres long and 50 metres wide, located southeast of Kyläniemi (Figure 23). The bedrock rises 4.3 metres above the lake level to the centre of the island. The shores range from gentle to quite steep. The bedrock is composed of pegmatite granite, granite and mica gneiss. Two bedrock exposures next to the lake shore were studied (Figure 24).

Figure 23. Location of Värrötsaaret South, southeast of Kyläniemi.

Exposure 1 - (6796404 N, 568936 E) Exposure 1 is located on the eastern side of Värrötsaaret South (Figure 24). The exposure is 41 metres long and 6 metres wide. The shore is gentle. The bedrock rises approximately 1.8 metres above the lake level at 7 metres' distance. The bedrock is composed of mica gneiss with granite dykes. Two joint plane sets were mapped at Exposure 1. The main joint plane set strikes 130° dipping 80°-90° towards the NE. Joint frequency ranges from 0.1 m to 3.5 m. Another joint plane set strikes between 030° and 060° dipping 80° to 90° towards the NW. In this set, joint frequency is low ranging from 0.5 m to 3.5 m. The foliation in the mica gneiss strikes 085° dipping 75° towards the N.

Exposure 2 - (6796380 N, 568886 E) Exposure 2 is located on the western side of Värrötsaaret South (Figure 24). The exposure is 45 metres long and 15 metres wide. The shore is quite steep. The bedrock rises approximately 4.3 metres above the lake level at 6 metres' distance. In the southern part of Exposure 2, the bedrock is composed of granite with mica gneiss inclusions. The main joint plane sets in granite strike 140° or 320° dipping 85° towards the NE or SW, respectively, and 230° or 050°dipping 70°-85° towards the SE or NW, respectively. Joint frequency is low ranging from 0.5 m to 3 m. In the northern part of the exposure, the bedrock is composed of mica gneiss and granite veins. The main joint plane sets in mica gneiss strike 055° dipping 75° NW and 290° dipping 65° S. Joint frequency is 0.5 m.

Four different GPR lines (lines V1, V2, V3 and V4) were studied in Värrötsaaret S (Figure 25). All lines were measured with a 100 MHz antenna. Line V1 is 59 m long, line V2 25.8 m long, line V3 55 m long and line V4 is 46.5 m long.

Figure 24. Location of Exposures 1 and 2 and the GPR lines studied on Värrötsaaret South. The pulling direction is also indicated with arrows.

Figure 25. Two GPR profiles (100 MHz antenna) of subsurface joint structures on Värrötsaaret South: A) GPR line V1 where joint planes in granitic bedrock penetrate at least down to 18 metres. B) GPR line V2 showing horizontal and sub-horizontal joint plane reflections down to ca. 12 m depth. Green lines indicate the main weakness zones and joint sets within the upper part of the bedrock.

Koukkuluoto

Koukkuluoto is a ca. 240 metres long and 50 metres wide islet located south of Kyläniemi (Figure 26). The bedrock rises approximately 1.8 metres above the lake level to the centre of the island. The shores of the islet range from flat to gentle. The bedrock is composed of pegmatite granite and mica gneiss. Two bedrock exposures next to the lake shore were studied on Koukkuluoto (Figure 27).

Figure 26. Location map of Koukkuluoto situated south of the Second Salpausselkä.

Exposure 1 – (6796990 N, 569915 E) Exposure 1 is located on the western side of Koukkuluoto (Figure 27). Exposure 1 is 230 metres long and 30 metres wide. The shore is flat. The bedrock rises only a few tens of centimetres above the lake level. The bedrock is composed of mica gneiss and pegmatite granite. Mica gneiss contains pegmatite granite dykes with garnet. In the northern part of the exposure, the main joint plane direction in mica gneiss strikes 30°- 55° dipping 80°- 85° NW. Joint frequency is between 10 cm – 5 m; most often more than 1 m. In this northern part, there is also a joint set that strikes 300° - 320° dipping on average 80° towards the SW. In the southern part of the exposure, the main joint plane direction in pegmatite granite is striking 325° dipping 80° towards the SW. Joint frequency ranges between 5 cm – 1 m.

Bedrock foliation was also observed with a strike of 270° and dip 50° towards the south.

Exposure 2 – (6797100 N, 569903 E) Exposure 2 is located on the eastern side of Koukkuluoto (Figure 27). Exposure 2 is 50 metres long and 10 metres wide. The shore is gentle. The bedrock rises approximately 1.8 metres above the lake level at 11 metres' distance. In the south, the first 12 metres of the exposure (6797085 N, 569925 E) are composed of mica gneiss with some dykes of granite and pegmatite granite. The next 25 metres of the survey line are composed of coarse-grained pegmatite granite and the rest of the exposure in the northern part (6797085 N, 569925 E) is composed of mica gneiss with dykes of pegmatite granite. The main joint plane direction is 300°-305° dipping 75°-80° towards the SW. Joint frequency ranges between 0.5 – 3 m. A secondary joint set striking 220° and dipping 75°-85° towards the SE occurs in the southern and northern parts of the exposure with joint frequency ranging between 0.5 m – 11 m.

Figure 27. Location of bedrock exposures on Koukkuluoto. The strike and dip of the main joint plane sets is also indicated.

Three GPR lines (lines O1, O2, O3) were investigated on Koukkuluoto (Figure 28). All lines were measured with a 100 MHz antenna. GPR line O1 is 59 metres long and was measured from Exposure 1 to Exposure 2 in SW-NE direction (Figure 28). GPR line O2 was 48 metres long and was measured along Exposure 2 from the SE to the NW (Figure 27). GPR line O3 is 70 metres long and it was measured along Exposure 1 from the NW to the SE (Figure 28). The GPR profiles indicate that bedrock foliation is possible to detect down to 15 meters within the subsurface while horizontal reflections most likely represent horizontal jointing related to the cubic jointing pattern in the bedrock (Figure 29).

Figure 28. Location of three GPR lines (O1 – O3) investigated on Koukkuluoto. Blue arrow heads indicate the radar pulling direction.

Figure 29. 100 MHz GPR profiles O1 – O3 from Koukkuluoto. A) GPR profile from Line O1, B) GPR profile from Line O2 and C) GPR profile from Line O3. Green lines indicate the main weakness and joint sets within the upper part of the bedrock. Continuous sub-parallel reflections further down in the subsurface are thought to represent bedrock foliation.

Peräsaaret East

Peräsaaret East is a small island on the northern side of the Kyläniemi Peninsula (Figure 30). The bedrock is mainly composed of granite with mica gneiss inclusions. Two bedrock exposures were studied in the eastern part of the island.

Figure 30. Location of Peräsaaret East north of Kyläniemi.

Exposure 1 - (6800712 N, 564545 E) Exposure 1 is located on the eastern side of Peräsaaret E (Figure 31). The exposure is 30 metres long and 10 metres wide. The shore profile is almost flat. The bedrock rises approximately 1.8 metres above the lake level at 20 metres' distance. In western and eastern part of the exposure, the bedrock is composed of pegmatite granite (quartz grains 0.5-2 cm and feldspar grains 2 cm) and in middle part of the exposure, of homogenous medium grained granite (quartz grains 2-3 mm and feldspar grains 1 cm). The main joint plane set strikes 060° or 240° dipping from 85° to 90° towards the NW and SE respectively. Joint frequency ranges from 0.1 m to 8 m. The secondary joint set strikes 130° dipping 70° towards the NE. Joint frequency ranges from 0.2 m to 6 m being 3 m on average.

Exposure 2 - (6800692 N, 564549 E) Exposure 2 is located on the southeastern side of Peräsaaret Eeast (Figure 31). The exposure is 30 metres long and 19 metres wide. The shore is gentle. The bedrock rises approximately 1.8 metres above the lake level at 7 metres' distance. The bedrock is composed of pegmatite granite that contains inclusions of mica gneiss. The main joint plane set strikes 060° or 240° with a vertical dip (90°). Joint frequency ranges from 4 m to 6 m. Another sub-parallel joint plane set strikes 215° dipping 85° towards the east. The foliation in mica gneiss strikes 120° dipping 75° towards the NE.

Figure 31. Location of the exposures studied on Peräsaaret East. The strike and dip direction of the main joint plane set is also indicated.

Two GPR lines (lines PE1, PE2) were studied on Peräsaaret E (Figure 32). Both lines were measured with a 100 MHz antenna. GPR line PE1 is 33 metres long and GPR line PE2 is 30 metres long. The main bedrock structures in the subsurface are indicated in Figure 33.

Figure 32. Location (blue lines) and pull direction (blue arrow heads) of GPR lines PE1 and PE2 studied on Peräsaaret East.

Figure 33. GPR profiles (100 MHz antenna) of subsurface joint structures on Peräsaaret E: A) GPR line PE1 where joint planes in granitic bedrock can be seen down to 12 metres. B) GPR line PE2 showing horizontal and sub-horizontal joint plane reflections in granitic and mica gneiss bedrock down to 15 metres. Green lines indicate the main weakness zones and joint sets within the upper part of the bedrock.

Vehmastinniemi

Vehmastinniemi is located on the west side of Kyläniemi proper (Figure 33). The bedrock is mainly composed of pegmatite granite. The bedrock rises 41.8 metres above the lake level to the highest point of Kilpiänvuori, which is 250 metres north of Exposure 1 located next to the lake shore studied here (Figure 34).

Figure 34. Location of Vehmastinniemi.

Exposure 1- 6794846 N, 562574 E Exposure 1 studied on the western side of Vehmastinniemi is 35 metres long and 13 metres wide (Figure 35). The shore is quite gentle. The bedrock rises 4.3 metres above the lake level at 40 metres' distance. The bedrock is composed of coarse-grained pegmatite granite. The main joint set planes strike 330-340° dipping 80°-90° towards the SW. Joint frequency ranges from 0.5 m to 1 m. The secondary joint plane attitudes strike 55°-60° dipping between 72°to 90° towards the NW. Joint frequency is low, 5 m on average.

Five different GPR lines (lines SI1, SI2, SI3, SI4 and SI5) were made in Vehmastinniemi (Figure 35). GPR lines SI1 (11 m long line) and SI2 (15 m long line) were measured with a 100 MHz antenna. GPR lines SI3 (14 m long line), SI4 (23 m long line) and SI5 (13 m long line) were measured with a 250 MHz antenna. GPR soundings penetrate down to 10 – 12 metres from the bedrock surface and the reflection surfaces and hyperbola-reflections are sub-parallel and partially diagonal over the whole depth of the upper 10 to 12 metres (Figure 36).

Figure 35. Location of GPR lines in Exposure 1, Vehmastinniemi. GPR lines SI1, SI4 and SI5 were investigated with a 100 MHz antenna and lines SI2 and SI3 with a 250 MHz antenna. Arrow heads indicate radar pull directions.

Figure 36. GPR profiles from Vehmastinniemi exposure: A) 100 MHz GPR profile of line SI1, B) 250 MHz GPR profile of line SI2, C) 250 MHz GPR profile of line SI3, D) 100 MHz GPR profile of line SI4, E). 100 MHz GPR profile of line SI5 showing the main weakness zones and joint sets within the upper part of the bedrock down to ca. 10 m depth. Strong reflections at ca. 16 metres' distance in profile D most probably indicate an almost vertical open joint exposed to bedrock surface.

Peltoinlahdensaari

Peltoinlahdensaari is an island, ca. 200 metres long and 120 metres wide, located on the northern side of Kyläniemi (Figure 37).

Exposure 1 - (6798840 N, 565483 E) Exposure 1 is approximately 40 metres long and 20 metres wide (Figure 38). The shore is gentle. The bedrock rises 1.8 metres above the lake level at 10 metres' distance. The bedrock is composed of granite that contains mica gneiss inclusions. The main joint plane set strikes between 300 and 310° dipping 70°-75° towards the SW. Joint frequency is 0.3 m – 1.5 m. The secondary joint plane set strikes 260° dipping 85° towards the south. Joint frequency ranges from 1 m to 2.5 m.

Figure 37. Location of Peltoinlahdensaari, north of Kyläniemi.

Figure 38. Location of Exposure 1 on Peltoinlahdensaari. The main joint plane attitude (strike 305°, dip 72° SW) is also indicated.

Halkosaari

Halkosaari is an island, which is 130 metres long and 150 metres wide, and located 9 kilometres north-west of Kyläniemi (Figure 39). One exposure was studied in the western part of the island (Figure 39).

Exposure 1 - (6808435 N, 557403 E) Exposure 1 studied in the centre of Halkosaari is approximately 50 metres long and 30 metres wide. The bedrock rises 9.3 metres above the lake level to the centre of the island. The shores of the island are quite gentle. The bedrock is composed of

amphibolite and pegmatite granite. In the northern part of the exposure, the bedrock is composed of amphibolite. The main joint plane set in this part strikes 100° dipping 65° towards the north. Joint frequency ranges from 0.1 m to 2 m. In the southern part of the exposure, the bedrock is composed of pegmatite granite where no joint plane sets were seen.

Figure 39. Location of Exposure 1 and the strike and dip of the main joint plane set on Halkosaari.

Hiidensaari

Hiidensaari is an island ca. 400 metres long and 200 metres wide, located 9 kilometres north of Kyläniemi (Figure 41). One exposure was studied on the island (Figure 42).

Exposure 1 - (6808480 N, 557082 E) Exposure 1 is 30 metres long and 9 metres wide. The shore is gentle. The bedrock is composed of coarse-grained granite with mica gneiss veins. The main joint plane set strikes 070° dipping 90°. Joint frequency is low, 3 metres on average.

Figure 41. Location of Hiidensaari.

Figure 42. Location of Exposure 1 and the strike of the vertical main joint plane set on Hiidensaari.

Vuoriniemi

Vuoriniemi is located 11.5 kilometres north of Kyläniemi (Figure 43). One exposure was studied in Vuoriniemi (Figure 44).

Exposure 1 - (6809659 N, 568041 E) At Exposure 1, the shore is gentle with the bedrock rising 4.3 metres above the lake level at 25 metres' distance (Figure 43). The bedrock is composed of tonalite where the main joint plane strikes 230° and dips 72° towards the SE. Joint frequency is low, 2 m on average.

Figure 43. Location of Vuoriniemi, nine kilometres north of Kyläniemi.

Figure 44. Location of Exposure 1 in Vuoriniemi and the main joint plane direction in tonalite bedrock.

APPENDIX 2 - Summery table of geological observations of joint structures and bedrock types at the sites studied Name of the site Location Main bedrock Average attitude The average joint The attitude of The average joint studied and the (x, y) type of the main joint plane spacing secondary joint plane spacing exposure plane set (strike (main joint set) plane sets (strike (secondary joint number and dip) (m) and dip) set) (m) Talsionsaari Exposure 1 6793925 N pegmatite granite 340°/85°W 0.5 250°/85°S 1 564635 E MFS MFS Exposure 2 6794937 N mica gneiss and 160°/70°E 0.3 080°/80°N 2 564128 E pegmatite granite MFS LFS

Exposure 3 6794581 N migmatite with 350°/75°W 0.2 080°/80°N 1.5 564513 E granite veins HFS LFS Exposure 4 6794527 N migmatite with 330°/85°SW 0.7 220°/90°SE 3 564549 E granitic veins MFS LFS 61 Exposure 5 6794154 N pegmatite granite 145°/85°NE 2 055°/85° NW >2 565363 E with mica gneiss LFS LFS inclusions Susiniemi Exposure 1 6794793 N granodiorite/ no joints no joints no joints no joints 563627 E granite LFS LFS Suuri Mäntysaari Exposure 1 6797543 N pegmatite granite no observations no observations no observations no observations (see Appendix 1) 556588 E Exposure 2 6797341 N pegmatite granite 035°/75°NW 0.4 330°/85°SW 0.5 555957 E MFS MFS Exposure 3 6797368 N pegmatite granite 330°/80°SW 0.5 285°/80° 1 556040 E MFS MFS

Exposure 4 6798043 N pegmatite granite 220°/60°SE 0.2 120°/80°NE 0.5 556306 E with mica gneiss (050°/80°NE) HFS MFS inclusions

Paskaluoto Exposure 1 6797115 N pegmatite granite 135°/70°NE 0.5 no no 558284 E with mica gneiss MFS LFS inclusions Exposure 2 6797112 N pegmatite granite 220°/40°SE 0.5 no no 558211 E with mica gneiss MFS LFS inclusions Hietasaari Exposure 1 6800069 N mica gneiss wit 270°/85°S 0.8 020°/75°W >1 559101 E pegmatite granite MFS LFS

veins 62 Ojatsunsaari Exposure 1 6800896 N pegmatite granite 020°/75°W 0.6 060°/80°NW >1 562082 E with mica gneiss MFS LFS inclusion Exposure 2 6800899 N, pegmatite granite 280°/75°S 2 no no 562041 E with inclusions of LFS LFS mica gneiss Soukkioniemi Exposure 1 6799921 N, mica gneiss with 080°/85°N 0.4 140°/75°NE 2 560769 E granite veins MFS LFS Korkiatsaaret N Exposure 1 6795654 N granite with mica 060°/85°NW 0.5 090°/85°N 0.5 564948 E gneiss inclusions MFS MFS Exposure 2 6795655 N granite and 325°/85° SW 1 230°/85° SE 2.5 564990 E pegmatite granite MFS LFS

Värrötsaaret S Exposure 1 6796404 N mica gneiss with 130°/85°NE 0.4 050°/85°NW >0.5 568936 E granite dykes MFS LFS Exposure 2 6796380 N mica gneiss with 140°/85°NE and >0.5 050°/80°NW and >0.5 568886 E granite dykes SW LFS SE LFS Koukkuluoto Exposure 1 6796990 N mica gneiss and 040°/82°NW 1 310°/80°SW 0.4 569915 E pegmatite granite MFS MFS Exposure 2 6797100 N mica gneiss and 305°/78°SW 0.5 220°/80°SE 1.5 569903 E pegmatite granite MFS LFS Peräsaaret E Exposure 1 6800712 N granite and 060°/87° NW and 0.5 130°/70°NE 3 564545 E pegmatite granite SE MFS LFS Exposure 2 6800692 N granite with mica 060°/87° NW and 5 no no

564549 E gneiss inclusions SE LFS LFS 63 Vehmastinniemi Exposure 1 6794846 N pegmatite granite 335°/85°SW 0.7 060°/80°NW 5 562574 E MFS LFS Peltoinsaari Exposure 1 6798840 N granite with mica 305°/75°SW 0.5 260°/85°S >1 565483 E gneiss inclusions MFS LFS Halkosaari Exposure 1 6808435 N amphibolite and 100°/65°N 0.3 no no 557403 E pegmatite granite HFS LFS Hiidensaari Exposure 1 6808480 N, granite with mica 070°/90° 3 no no 557082 E gneiss veins LFS LFS Vuoriniemi Exposure 1 6809659 N tonalite 230°/72°SE 2 no no 568041 E LFS LFS