Structural Analysis Of The East Life Coast History Essay
Early Carboniferous sedimentary rocks crop out on the coast of East Fife. Detailed geological analysis of the sedimentary succession, based on the constructed logs, provides evidence that the rocks were deposited predominantly in fluvial-deltaic system. Presence of several limestone beds containing fossils of marine organisms indicates on fluctuations in sea level during the Early Carboniferous. The rock sequence in the study area has also undergone structural disturbance caused by the major easterly and south-easterly trending faults. The strata in the area have been also folded about northerly to north easterly trending axes, forming gentle synclines and anticlines. This suggests being the result of the east-west compression.
The geological mapping project was done in the district of east Fife, which is part of county of Fife, Scotland. The mapping area covered the coastal section from the point [NO0806290], to the south-west of Fife Ness, till the point [NO57821485], about 600 metres to the north-west of Kenly Water mouth. The rock exposures in the study area run mostly sub-parallel to the coast line forming prominent ridges in certain sections. Topographically the area is at sea level, except few high standing outcrops, thus the coast is very tide dependent.
Mapping took place in June-July 2010. It included 30 days working in the field (some of the days were shorter due to high tides) and producing detailed geological map. The rocks were differentiated based on the lithological variability; each mapping unit represents either individual or group of rock lithologies (depending on the thickness of the rocks).
After mapping the area, the detailed analysis of sedimentology and structural geology was carried out, based on the data collected in the field. The first objective was to provide a detailed description of the sedimentary succession exposed on the coast of East Fife, producing few sedimentary logs, and suggest the depositional setting for this rock sequence.
The second objective was to analyze the structural complexity of the area and its influence on the stratigraphy.
The rocks exposed in the area are almost fully sedimentary. As the sedimentary rocks alternate and the same type of rock lithologies reappear again through the sequence, it is hard to fully assign the rocks to any exact age based on lithology.
The most common clastic rocks present are sandstones, shales, siltstones and mudstones.
Few lenses of conglomerate are present in the area. These are within the oldest rock sequence in the study area. They contain reddish coloured mud clasts (1-2cm) and some carbonate pebbles. The rounded pebbles are dominant. Conglomerate is matrix supported, as the clasts do not touch each other. The matrix is composed of reddish coloured fine grained sandstone. The base of the conglomerates is erosional surface.
Sandstones outcrops can be generally divided into five groups.
The oldest sandstones beds in the area crop out to the north of Balkonie Sands. They are grey, red and purple in colour. The beds are up to 1 m thick. These sandstones are alternating with thinner beds of mudstone and siltstone (<50cm). Sandstones are fine to medium grained, moderately sorted with subrounded grains. Those sandstones have no evidence of any fossil presence.
Another type of sandstone beds are grey and yellow in colour. The beds are of medium thickness (<1.5m). Sandstones are fine to medium grained. These beds are alternating with thin beds of grey coloured mudstones and siltstones forming detectable fining up packages. Grey coloured sandstones are much harder than the yellow ones. The bedding surface of the grey sandstone beds is also much flatter and the fractures present on their surface show much more clearly defined pattern. Both sandstones are composed predominantly of quartz, however, there are also biotite and feldspar grains present in the grey sandstones. These grains are less obvious or rare in the yellow ones.
Thick beds of sandstone are another variant of rocks of such lithology exposed in the area. They mainly occur at Fife Ness and form it on the whole. These sandstones are medium grained, white and pinkish in colour, with not flat bedding surface. They are not well cemented, soft and fragile. Quartz is dominant mineral in composition, however there is significant amount of CaCO3 present in it, as the rock reacts with acid. Sandstones are with a lot of soft sediment deformation and cross bedding structures. There is no evidence of any organic matter or fossils in those thick beds.
Another type of thick sandstones is part of the younger rock sequence. These sandstones are fine to medium grained and are only yellow in colour. The rocks are well sorted with subaangular grains. Composition of these sandstones is predominantly quartz, however there is certain amount of CaCO3 mineral as the rock react with acid. Some of such sandstones are quite soft and fragile, where as others are hard. Plentiful sedimentary structures such as cross bedding, ripples (climbing and asymmetrical) and ripple marks are widespread on their surfaces. The bedding surface of such sandstones is irregular and similar to Fife Ness type thick sandstones, with a lot of soft sediment and slump structures. However, unlike Fife Ness type sandstones, these contain rootlets of plants, which are altered to coal now. A lot of tree fossils, which are recrystallised or turned to coal, preserving the clear shapes are comprised in those sandstones. Nodular and pipe like structures, made from ironstone are present on the surface of few sandstones. Such thick beds of yellow sandstone crop out at Babbet Ness, to the north of Kingsbarns Harbour and within the Randerstone section.
Thin beds of sandstone (0.5-1 m) grey and white in colour, is another type of sandstone present in the study area. It is fine to medium grained, well sorted rock with subangular grains. Sandstones are well sorted. Major mineral in the composition is quartz. Certain amount of feldspar and mica (shiny muscovite and black biotite) present as well. The bedding surface of such sandstones is fractured and relatively flat. The fractures are not filled with any mineral. Rootlets of plant material, now altered to coal are very common in those sandstones. Cross bedding and ripples are the major sedimentary structures present in these rocks.
Mudstones, siltstones and shales
These rocks mainly form alternating beds with grey, white sandstones and carbonate rocks. Two types of mudstones and siltstones are present. The first type is reddish coloured beds, which are the older ones, interbedded with red and grey sandstones to the north of Balkonie Sands The second type are grey coloured mudstones and siltstones, which are interbedded with grey and white sandstones and are within the younger sequence of rocks The thickness of the individual beds vary, most of them are less than 50 sm. Few wide outcrops of poorly bedded mudstone and shale appear in the area. These are common near the fault plains and sandy beaches. Mudstones and shales contain many trace fossils.
Carbonate rocks are represented by rare dolomites and several thin beds of limestone.
Limestones composed of the bioclastic material. The matrix is lime mud. The bioclasts in the limestones touch each other, hence the rocks are packstones. These bioclasts are fossilized shells of the organisms such as bivalves and brachiopods. The rocks have yellow or grey weathering result colours. These limestone beds are contained in between the shales.
One of the limestone beds [NO] within the Randerston section contains algal balls.
Rare dolomites beds are orangy in colour. The rock is very hard, dense and doesn't react with an acid very well.
Several black to grey coloured coal beds are present in the study area. They are relatively thin beds, no more than 50 sm. These coal horizons are contained in between the shales
Igneous rocks appear to be very rare in the study area. Two small subrounded igneous bodies crop out at south east of Balkonie Sands. They are black coloured, fine grained and have crystalline texture. These could be boulders as they crop out from the sands Few dyke intrusions cutting through the sedimentary beds are near Fluke Dub [NO]. Dyke is dark coloured, with a fine grained crystalline matrix. This is basaltic intrusion.
Another elongated igneous body cuts through the thick sandstone beds near Salt Lake [NO]. The feature continues for about 200 metres trending towards north. It is best exposed at high water mark. It is basic igneous rock, which has dark coloured fine grained matrix with quite large anhedral black coloured crystals which are pyroxene phenocrysts. The rock is basalt.
Stratigraphy have to write thickness for all of them
The stratigraphical relationship between the beds in the area is complex as there are several faults running across the coast, causing certain displacement in the strata. That is why it is hard to trace connected stratigraphical sequence for large distances. Same type of rock lithologies, are repeated in successive outcrops, however they are different in age. Different sections to which the area is divided by major faults are described in stratigraphical order.
Overall thickness of the strata in the study area isâ€¦.
Upper Old Red Sandstone
The oldest rocks in the area are exposed to the north of Balkonie Sands between the points [NO63101041] on the east and [NO62301060] on the west. The rocks in the section are mainly reddish and grey coloured sandstones alternating with red mudstones. Few wide outcrops of poorly bedded mudstone are also present. The beds dip generally NW. The eastern parts of the outcrop are clearly disturbed. Small strike slip faults and folds are the result of such disturbance. This outcrop of rocks is assigned to Upper Old Red Sandstone by Macgregor (1968) and Geikie (1902).
The area between the Kingsbarns fault and the north part of Cambo Ness at Cambo sands was also described by geol surv book 1977 as being similar and correlating with the Balkonie beds of upper old red sandstone.
Calsiferous Sandstone Measures
Fife Ness Beds
On the western end near Fluke Dub, Balkonie Beds pass conformably to Fife Ness Beds which are of Carboniferous age. The beds are mainly of grey sandstones interbedded with mudstones and siltstones. They continue dipping NW and this continuity is disturbed by the Worminstone fault [NO] which caused an upthrow of Balkonie beds together with the lower part of Fife Ness Beds.
Steep beds, dipping W, on the east side of Balkonie Sands, near Constantine's Cave, together with rock exposures all over Fife Ness form the top part of the Fife Ness Beds without any overlap with the beds near Fluke Dub. The sequence is disturbed to the south west of Fife Ness by Dane's Dike fault. Few other small faults are present through the section, but they seem to cause no big gaps or repetition within the strata. The base of the section is composed of alternating well bedded sandstones with thin beds of mudstone and siltstone. The top part composed mainly of thick white, pinkish sandstones which form a prominent ridge at Fife Ness.
Few faults crossing the top part causes some repetition in the section.
Randerston-Babbet Ness Beds
The rocks of this formation have thin beds of shelly limestone present in the sequence. Sandstones within this sequence are also different from the ones in other formations, as they contain much organic material such as plant rootlets and tree fossils. Another characteristic feature of this formation is presence of thin coal beds. The formation is divided into 4 smaller sections by major faults. These sections are described in detail in the order from oldest to youngest.
Randerston section lies between the Worminstone fault [NO] and Cambo fault [NO]. Thickness of strata is about ____ The base of the section lies between Wormistone and Randerston fault, which causes disturbance within the section. The beds dip to the NW and then swing to SE as they are folded into the syncline, with well exposed eastern limb. The beds are mainly grey coloured sandstones interbedded with mudstones and shales. Three
The rocks to the north of Randerston Castle fault plain comprise the top of the section. The folding caused change of the bedding dips twice: from SE to NW forming a gentle dome [NO] and back to SE forming syncline near the end of the section. The sequence of beds is repeated in reverse order after the synclinal axis. The youngest rocks in the section are in the centre of the syncline. Yellow and grey coloured rooty beds of sandstone with alternating mudstones and shales make up the most of the section. Eight thin beds of fossiliferous limestone in between the shales and muds are present in the sequence. The youngest limestone bed is in the centre of the syncline.
Kingsbarns Harbour-Babbet Ness section.
The section includes the area between Kingsbarns fault and Babbett Ness fault. The thickness of the strata is ____The base of the section lies between the Babbet Ness fault and the Airbow Point and is poorly exposed. The rocks dip moderately to SW and to SSE closer to Kingsbarns Harbour as the beds are gently folded. generally are older moving towards north west. Are they the youngest in the area???The rocks are mainly yellow coloured thick beds of soft and hard sandstones and beds of shales and siltstones. Few limestone beds with bivalve shells were found between the shales.
The rocks near Arbow point are poorly exposed
Babbett Ness-Craig Hartle syncline
The rock exposures of this section sequence of rocks Thickness of the strata is _____On the east of the section rocks are folded, forming Babbet Ness anticline. The sequence of rocks on the both limbs repeats. It consists of thick beds of rooty sandstones, mudstones and limestones within the shaly sequence. The strata on the west of the anticline, near Salt Lake, dip gently towards the WNW. The rocks are mainly thick beds of rooty sandstone with few thin limestone beds, which are between the shales. The youngest rocks of the section are in the centre of the syncline.
Kilminning castle section.
The section lies between the southern side of Kilmining Castle and Dane's Dike fault. The thickness of the strata is about ___ and mainly consist of sandstone beds interbedded with some mudstone and siltstones. Few carbonate beds (dolomite and limestone) are present. Bedding dips are gentle. The section is displaced by two faults in the middle, however the displacement is probably small. The rocks are folded and dips of the beds swing from south to south east near Kilminning castle and then to the north east, near Dane's Dike fault.
The area of Upper Old red sandstone is completely disoriented, especially eastern part, closer to Balkonie sands. Such disoriented beds were described as cryptovolcaniic structures by (geol survey book)
Presence of reddish, purple colours in those outcrops is an indication of these rocks being terrestrial. Such colouring is also typical for semi arid climate conditions, when the water table is low and this causes an oxidation of the iron in the rock (FeOX), which gives it such colour. So the two hypotheses could be that these are either fluvial or aeolian environment deposits. However the sorting and roundness of grains in the rocks provides an evidence of certain transport history. The alternation in grain size of the rocks exposed at the Balkonie implies that their deposition occurred during alternation of high and low energy processes. The presence of conglomerate bands with pebbles of mud is an indication of erosion and transport of preexisting rocks by high energy currents and deposition as the flow energy drops. This is very characteristic for fluvial environment deposits. The mudstone beds represent probably river flooding deposits when the flow energy was very low or stagnant, where as sandstones with cross bedding structures are the result of relatively high energy currents -river channel deposits. Lack of fossils in those outcrops is also probably an indication of fresh water environment, where we don't usually find fossils.
The rocks exposed at Fife Ness imply that they were deposited during predominantly high energy processes. Sandstone beds interbedded with mudstones, shales and siltstones at the base of the sequence are representing alternating of energy forces Overlying those beds are thick beds of sandstone which are stacked on one another, clearly showing erosional scours at the base. This proves the presence of some high energy turbulence currents creating such erosional features. These sandstones are channel deposits, which could be river or distributary channels at delta tops. Presence of a lot of current structures (cross bedding), which show multidirectional flow, on such thick sandstones is an evidence of changing of the direction of flow through time. This could happen as the result of the lateral shifting of the channel, when the new channel erodes the previous one. Slumping structures which are also characteristic of deltaic environment present on some of the thick sandstone beds. General coarsening up and fining up successions and sorting of the rocks imply deposition in between Fluvial and Deltaic (delta top) environment. However presence of very thick sandstone beds with very little mud (about 85% of the section is sand), lack of fossils and coal horizon, which is characteristic of deltaic environment, supports the assumption that fluvial component in the deposition of those beds was more dominant.
Fluke Dub section.
Presence of two thin beds of carbonates (dolomite and limestone) at the base of the section is showing that input of clastic rocks has been ceased at certain times, as this is necessary condition for precipitation of CaCO3. So the fluvial-deltaic environment was replaced for very short time by lagoon or intertidal environment where these thin beds of limestone were formed. Such environment was also suitable for living organisms. Fossilized shells of such organisms cemented together are found in the limestone matrix. The rest of the section predominantly consist of relatively well sorted grey and yellow sandstone beds alternating with mudstones and siltstones forming fining up packages are characteristic of fluvial environment. Cross bedding structures present on the sandstones also show that these are flow current deposits, probably river channel deposits.
Kilminning Castle-Dane dike fault
Some thick beds of sandstone (0.8-1 m) with medium scaled (10cm) cross bedding structures oriented in the same direction clearly indicate unidirectional flow. This could be deposits of river or delta channel. Few thin carbonate beds are present through the sequence. These are mostly dolomite beds which are probably deposited in intertidal environment. Thin limestone bed containing calcareous shells at [NO] represents represent the periods of termination of the siliciclastic sediment influx, so that limestone precipitated. These shells are Carbonicola antique shells (Kirkby 1880,p 578; Bennison 1960) which are non marine bivalves. So they indicate that this bed was formed no under marine conditions.
Presence of medium grained sandstone beds alternating with mudstones and siltstones clearly indicate that there have been both low-stagnant and relatively higher flow regimes. Shales and mudstones make up significant part of the section. Some shales contain rootlets. Thin coal beds found in between those shales. Presence together with rootlets, are indicators of subaerial exposure. Depositional setting is delta top
Wavy bedding in finer grained facies
Sandstone forms about 80% of the section. The section contains 8 thin beds of limestone and most of them contain calcite shells of marine bivalves. Presence of marine fossils in those beds is indication of ceasing of siliciclastic sediment influx during some period. These limestone beds are probably formed â€¦
Many soft sediment deformation and slump structures present in thick sandstones are the results of rapid deposition and compaction.
Presence of few thin coals within the section represent the periods of subaerial exposure. Rootlets present in the sandstones confirm these coals being in situ. Presence of a lot of rootlets in shales and sandstones are the evidence of exposure for a quite a long period of time, so that the plants grow. These beds probably represent floodplain or delta top which was frequently flooded.. Thick sandstone beds with medium to large sized cross beddings are deposits of fluviatile or deltaic channels. The sorting and roundness of the grains tells about the long transport history. This also could occur as the result of reworking.
The beds in the section starting north westward of Kingsbarns fault, where relatively thick limestone bed which is made of marine bivalve shells in the lime mud matrix.
Presence of marine fossils
Sedimentary structures on thick sandstone beds such as cross beddings of different scale and asymmetric ripples are the results of energy force alternation. Climbing ripples present in the upper part of the beds are the result of high sedimentary rate and is typical for deltaic environment
The rock sequence in the study area is structurally deformed forming cylindrical and non-cylindrical folds. Continuity of the strata is also disturbed by presence of several major faults running across the coast as well as small faults causing local displacements.
Danes Dike fault [NO 63600938] is exposed on the shore to the south-west of Fife Ness. Dip of the fault plain is quite steep at angle about 65 degrees to the south. It brings Fife Ness thick sandstones and Anstruther beds, which are on the hanging wall, next to each other on the sides of the fault plain. Considering that Fife Ness beds are stratigraphically lower than Anstruther beds, it suggests that it is a normal fault with a southerly downthrow for about 250-300 m
Easterly trending Cambo fault [NO 60881180], causes a disturbance in the continuity of the Randerston section, cutting through the western limb of the Randerston syncline which is to the south of Cambo Ness. Many small faults associated with the main one displace the beds on the western limb of the syncline. The movement on the fault plain resulted in positioning of the Fife Ness beds on the north side of the fault at Cambo Ness, to the same level with the Randerston beds, which are younger stratigraphically. The fault plain is dipping steeply, almost 80 degrees towards the south (Fig ) with a southerly downthrow for about 300 m
Fig. Stereographic projection of the Cambo fault plain.
Kingsbarnss fault [NO 60401240] is also easterly trending normal fault. The fault plain is dipping about 55Â° towards north. Stratigraphical consideration suggests the occurrence of significant northerly downthrow for about 600 m bringing Upper Olds Red Sandstones to the same level with Anstruther beds.
Folds and fold geometries.
Wormistone syncline is cylindrical fold structure with a north-easterly trending axis. The fold hinge line is almost horizontal, trending towards 047. The fold is gentle with an interlimb angle of 149Â°
The rock sequence in the Randerston section, are folded forming syncline between the fault next to the small anticline structure [NO 61621116] and Cambo fault. Eastern limb, with the beds dipping gently north-west, is much well exposed. On the western limb the same sequence of rocks are laid in the reverse order from the fold axis. The western limb is not fully exposed, as the Cambo fault cuts through the sequence and the beds are getting steeper at far end of the limb, approaching to the fault plain. The intrelimb angle is about 155Â°, which means the fold is gentle. The hinge line of the syncline plunges 4Â° towards 022 and it has north-easterly trending axis.
Fig Stereographic projection of a) Wormistone syncline b)Randerstone syncline
Another cylindrical fold structure in the area is Babbet Ness anticline. The beds on the western limb dip gently north-west, where as on the eastern limb beds dip to the south-east. The fold is also gentle with an interlimb angle of 150Â°. The fold hinge line plunges 5Â° towards 238 (Fig ).
Craig Hartle syncline is assymetrical fold (the cluster of poles for the western limb is more pronounced), located at the end of the study area, to the north of Kenly Water mouth. The beds on the eastern limb dipping gently towards north where as the beds on the western limb, dip steeply towards east. Interlimb angle is about
130 meaning it is an open fold. (Fig )
Fig. Stereographic projection of the a)Babbet Ness anticline b)Craig Hartle syncline
Two non-cylindrical folds are present in the study area. They are located to the north and south of the Kingsbarns fault [NO 60401240]. The beds at Kingsbarns Harbour form a closed circular structure with the beds gently dipping (10Â°) towards the centre. This is the basin with the youngest rocks cropping out in the centre of the structure. The longest axis of the basin is in north-east south-west direction.
Fig. Stereographic projection of the Kingsbarns fault plain
Easterly trending Wormistone fault [NO] and Randerston Castle fault [NO] are both steep, near vertical faults. Wormistone fault throws Balkomie beds together with Fife Ness beds. Randerston Castle fault northerly downthrow To the north of both of the faults the strata are folded forming syncline structure. This probably suggests that the deformation of the strata and formation of the synclines are
All the folds in the area are gentle and the orientations of the folds axes are in northerly to north-easterly direction. These two factors suggest that folds are probably the result of east-west compression during the same structural deformation event.
Most of the major faults are well exposed on the coast and generally trend east and south-east.
Kenly mouth fault [NO] is exposed at the mouth of the Kenly water. The fault trends towards east crossing the stream. The fault plain dips at about 40 degrees towards south. An influence of the fault on the rocks in terms of stratigraphy is not obvious. On both sides of the fault are the sandstone outcrops. The clear
Most of the beds in the study area are very gently folded along the strike. This is the result of regional tectonism which created the fractures on the surface of the beds within the study area. There are generally two clear fracture patterns on the bedding surfaces. In the first type the set fractures run parallel to the dip and strike direction crossing each other roughly at 90 degrees and forming rectangular forms on the surface of the bed. In the second type, fractures running subparallel to the dip direction intersecting those, which run parallel to the strike at angle 120 or 60 degrees forming rhomb shapes. The distance between the fractures also varies depending on the thickness of the bed. Analysis of the most of the fractured surfaces in the area suggests that the fractures are widely spaced in the thicker beds (Fig ). The other important fact is that fractures are not filled by any minerals, such as quartz.
Late Devonian-Early Carboniferous sedimentation
Caledonian mountain range, formed in northern part of Scotland as the result of the continental collision, was undergoing erosion during Late Devonian and Early Carboniferous. The land was high above sea level and rivers were bringing the clastic material from the northern upland areas to the southern lowlands. Scotland was near the equator with the semi arid climate, which is why most of the beds of that age have typical red colouration due to oxidation of iron minerals. Two exposures of red and purple coloured sandstones alternating with purple mudstones at Balkomie and Cambo sands which are the oldest rock exposures in the study area and probably of Late Devonian-Early Carboniferous in age. These rocks are terrigenous and were deposited in fluvial environment. They were assigned to the Upper Old Red Sandstone (Geikie 1902; Geol surv 1968) and this theory is probably right.
The majority of rocks, cropping out in the study area are of Early Carboniferous age. During this period Scotland was to the north of the equator and was part of the North American continent. On the south it was washed by the large ocean
The rivers were active during this period, bringing sediments from the north to the south and forming deltas, as the sediment influx was very high. It was a period of flourishing of the flora and fauna in the equatorial and tropical regions of the northern hemisphere. Vegetation was widespread in swampy areas near the delta tops and on the river banks. Trees and plants were buried by the sediment as the new river channels were cutting through those areas of vegetation and resulted in formation of the sandstones with rootlets of plant material, turned now to coal, and tree fossils. Presence of several coal horizons and a lot of plant material in shales also support the fact of much diversified fauna available at that time.
Presence of ripple marks and few "herringbone" structures on some of the grey coloured sandstones indicate the sea interaction and deposition of those rocks in shallow marine, coatal environment. Sea level was fluctuating many times during Early Carboniferous. There were periods when the land was subsiding and sea transgressions were taking place covering the southern parts of the Scotland by shallow, warm sea establishing marine conditions. Clastic sediment influx was probably ceasing during this period, which provided perfect conditions for organisms to live on the shallow shelf. Such sea level increases resulted in formation of thin limestone beds containing fossilized shells of those organisms which lived on shallow shelf during that time. At some point, when the slope gradient between the land and sea was increasing, rivers initiated the transport of big amount of clastic sediment to the sea and progradation of the river delta occured. This resulted in erosion of the preexisting rock sequence tops and deposition of thick channel fill sandstones. Such fluctuations in sea level created a cyclic pattern of alternating silisiclastic sediments and limestones which are mostly marine. Twelve limestone beds present within the Randerston section clearly represent this cyclicity. Shells of such marine organisms as were defined by these limestones of this section Number reference and types of organisms
Period of volcanic activity in East Fife is confirmed by presence of about a hundred volcanic necks in the different parts of the region (geol surv). One of such features representing volcanism is exposed in the study area. Near Salt Lake an elongate body cuts through the thick sandstones. This is volcanic agglomerate and few igneous basaltic intrusions with the pyroxene crystals. This feature was described first by Geikie (1902) and was referred as a volcanic neck. Geol surv made a suggestion that this structure is cryptovolcanic in origin.
Rock exposures on the coast of East Fife are dominated by sedimentary rocks deposited as the result of interaction of sedimentary processes in the fluvial-deltaic system. However several thin carbonate beds present within the sequence of Anstruther beds (particularly Randerston limestones) represent short periods of time when there were sea transgressions and establishment of marine environment. Ceasing of clastic material input, warm shallow and brackish sea water provided perfect conditions for flourishing of living organisms, such as mollusks and brachipods, which were preserved as thin shelly limestone beds in the rock record.
Such interchanging of fluvial-deltaic and shallow marine conditions resulted in formation of cyclic sedimentary packages with the large lateral variation of rock lithologies.
The rock sequence in the study area is also structurally complicated by faulting and folding. Continuity of the strata is disturbed by several easterly and south easterly major faults. Folds in the area are gentle with north and north- easterly axes. This suggests being the result of east-west compression.
When below sea level, the area was covered in sand and mud that was washed into the sea, leading to the formation of rocks such as sandstone, mudstone, and shale. Limestone also formed in part through the accumulation of dead sea creatures, but also through the precipitation of calcium carbonate in the tropical conditions. The shallow tropical seas of Carboniferous Scotland, much akin to the present day Bahamas, were full of life and much of this life became preserved as fossils in the rocks, including shellfish, corals, crinoids, sharks and other fish. When above sea level, the land was covered by tropical swamps, where forests of large trees, that were very unlike modern trees, flourished. Over time, the remains of trees that had fallen into the swamps were buried deeply and compacted, eventually forming peat, and finally coal.
Volcanic activity was another important feature of the Carboniferous. The continent at this time was being 'stretched', allowing magma to well up from the mantle to form many volcanoes.
The Midland Valley and the area around Orkney and Shetland were lower lying areas. In these areas away from the high mountains, sediment that had been eroded and washed from the mountains, such as boulders, pebbles, sand and mud, accumulated in alluvial fans, rivers, lakes and floodplains. This sediment formed the conglomerates, sandstones and mudstones that are found today, which is collectively known as the 'Old Red Sandstone'. Fish flourished in the rivers and lakes that existed here, we know this form their fossilised remains.
Cylindrical or non cylindrical fold
X bedding with curved bases and erosive tops
In the first map in some areas tha sandstones are straightly laminated
Most of the fife ness sandstones show the x beddings oriented in the same direction-unidirectional flow
Fractures on the surface of the beds
The roots in the shales would suggest that certain portions of the floodplain/delta top was exposed for rather long times, allowing for plants to grow (distal)
The difference in stratigraphical level between the groups of strata separated by the main fault suggests that it hasâ€¦â€¦downthrow
Describe the relationship between the trends of the faults, in particular strike slip faults and randerston and worminstone with the synclines which could be related to the same event of tectonism (shearing creating folds). On the other hand there are other normal faults which are of different event.
Presence of so many fossils is probably tells about the rapid sediment deposition.
Soft sediment deformation
Impression of trees on th
Some lenses of conglomerates with. Conglomerate, which contains carbonate pebbles(Greensmith 1965, pp. 256-257 in geol surv) was also found on the shore, at high water mark [NO]??? These rocks have no evidence of presence of any fossils.
Most of the exposures are getting covered by the water as the high tide comes, so the most serious hazards are high tides and high waves especially during windy days. Another thing to be careful of is falling down of steep beds which are very slippery especially when the tide goes low.
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