Moray and Caithness : a landscape fashioned by geology
0
Citation
0
Reference
20
Related Paper
Abstract:
The far north-east of Scotland encompasses a wide range of landscapes, from the rolling hills of Moray and the coastal flagstone cliffs of Caithness, to the blanket peat bogs of the Flow Country and the ancient rugged mountains of eastern Sutherland. These landscapes have all formed during a long and complex geological history, from rocks that were buckled and warped by continental collisions that occurred many hundreds of millions of years ago, to the sculpting of the hills and valleys by glaciers just a few thousand years ago. Since Neolithic times, the inhabitants of the region have made use of its geological resources and also changed its appearance irrevocably. This book describes the whole of that geological and human history, laying bare the events that have shaped the landscape of this remote but intriguing corner of Scotland.Keywords:
Landform
Historical geology
Cite
The excursion will take in areas (Figure 1) that exemplify the contrasting
scenery of Charnwood Forest, with its craggy knolls separated by featureless
tracts or smooth-sided valleys. This landscape is controlled by geology, and is
caused by the influence of erosion on rocks with very different physical
properties. The Precambrian rocks, which are the subject of this excursion, are
extremely resistant to erosion. They represent the tips of an ancient, rugged hill
range that is only now beginning to protrude through a covering of younger and
much softer Triassic strata, the latter in turn blanketed by Quaternary deposits.
Past workers have viewed Charnwood Forest’s topography as being a ‘fossil’ or
an ‘exhumed’ landscape, because a mountainous topography on the
Precambrian rocks was already in existence before being buried by younger
strata in Triassic times, about 240 million years ago. This ancient landscape is
dramatically revealed in the walls of Bardon Hill Quarry, which will be viewed
from the summit of the hill. It is only now emerging because the covering of
Triassic strata (and also Quaternary deposits) is being preferentially removed
by modern-day erosion (see inset to Figure 2).
Excursion
Cite
Citations (0)
Scotland affords several well-known localities for studying the mineral composition, order of deposition, and disturbance of the strata belonging to the older systems, but none of these exceed Shetland in interest. Here within a very limited area may be seen all the members of the metamorphic series; and flags, sandstones, conglomerates and breccias belonging to the Old Red Sandstone system, while the same variety of minerals is not to be found in any county in Scotland. Contemporaneous and intrusive igneous rocks are well represented, and their relations to the sedimentary strata are usually well seen either on the shores or in the bare rocky faces of the cliffs.
These islands have received considerable attention from geologists. In 1822 Dr. Hibbert published his “Description of the Shetland Islands,” a work abounding in geological research. Since then various papers have been published on the mineralogy and the geology of the islands, notably by Professor Heddle,* and by Messrs. Peach and Home* of the Scottish Geological Survey. Induced by the study of these writings I spent a few holidays last summer geologising in the northern part of the Mainland, and now venture to give a few remarks on that district, as the land phenomena are considerably different from what we are accustomed to meet with in the West of Scotland.
The town of Lerwick is built upon rocks of Old Red Sandstone age, which are well exposed on the shores to the east and west of the town. At these places the rock
This 250-word extract was created in the absence of an abstract
Shetland
Sketch
Mainland
Cite
Citations (0)
Red beds
Cite
Citations (18)
The Silurian rocks forming our great Southern Highlands have been examined and described by many geologists. We have had papers from Jamieson, Miller, Murchison, Nicol, Harkness, Geikie, Nicholson, J. C. Moor, Lapworth and Wilson, Hopkinson, Salter, &c., &c., and a considerable portion of these rocks has been described by the Geological Survey.
However, these rocks are so folded, twisted, faulted, and otherwise altered, that much steady and persistent work will still have to be done before all their relations can be properly understood.
These Silurian rocks, as seen on the map, occupy a broad strip of hilly country stretching from St Abb’s Head to Port Patrick. The whole country through which they range is a series of rounded hills and moory uplands. The hills are never peaked or rugged, but present for the most part a fine rounded outline, with gentle slopes covered with grass and heather, and the rocks generally have a covering of peat, sand, and other debris.
On passing over them, one aspect which particularly strikes the geological observer is their age as hills.
In many of the valleys we have a covering of Permian sandstones, and the present rivers are in some cases laying bare rocks which formed the beds of rivers which existed long before the Permian time. In passing up some of these valleys, I have sometimes found it very difficult to abstain from musing on the time when the hills before me formed part of an old continent, and the scene must have
Cite
Citations (1)
These northerly outposts of Scotland, best known perhaps for their hospitality and historic remains, also hold a fascination for the geologist. Reading the buckled and fractured rocks of Shetland tells of colliding continents and a history dating back almost three thousand million years. By contrast, the distinctive red sandstones of Orkney, were formed in more recent geological times, laid down in a long-disappeared freshwater lake. These strata hold the fossilised remains of bizarre early life forms that are now long extinct. Until 11,500 years ago, these islands, along with much of the Northern Hemisphere, were held in an icy thrall, known as the Ice Age, and it was these most recent events that helped to shape the landscape we currently recognise.
Further modification of the landscape continues to this day, as the roaring Atlantic breakers incessantly pound the coastline. Other elements of wind and rain also play their part; as does the hand of Man who has occupied this ancient landscape for over three millennia.
In this booklet, we also trace the changing environments to which the land that was to become Scotland was subjected as it drifted northwards from a position close to the South Pole to its present location. On this epic journey, this chunk of the Earth’s crust has travelled through all the Earth’s climatic zones and each has left its mark. All these environments are recorded faithfully, albeit incompletely and sometimes enigmatically, in the record of the rocks.
Geologist
Shetland
Cite
Citations (4)
Known more for its literary connections with Jane Austen
and the gardens of the naturalist Gilbert White at Selborne,
the Alresford district’s typically gentile English countryside
seen in the Alresford district is fundamentally a product of
the underlying geology. Commencing in the east, a journey
westwards begins on the low lying sandy heaths and heavy
clay pastureland around Bordon and Woolmer Forest,
developed from the Lower Cretaceous sands and clays.
Further south-east around Petersfield, the characteristic
ridge and vale country is founded on the alternating sands
and clays of the Lower Cretaceous Hythe and Sandgate
formations.
R ising steeply above the lowlands is the indented and
landslipped Upper Greensand scarp, behind which the land
slopes gently down to small villages such as Selborne and
East Worldham before rising steeply again up the Chalk
escarpment which forms perhaps the most striking feature.
This scarp, running north–south across the sheet district
effectively divides the region into two. Above the scarp the
high hills capped by clay-with-flint around Medstead and
Four Marks gently descend eastward down the long gentle
dip slopes of the Chalk to the headwaters of the Itchen
around New Alresford. The majority of the East Hampshire
Downs with its dry valleys and gently rolling hills is underlain
by the Chalk.
T he landscape seen today is the result of a very long
geological history which stretches back to the Early Jurassic
and beyond. The rocks at surface and those beneath the district
give valuable information for the understanding of such
major earth history events as the opening of the Atlantic and
the Channel Basin, the drowning of most of Europe during
the Cretaceous Period, the Alpine earth movements and the
wide climatic variations in our most recent past.
T hese events have also created the conditions for the
development of oil and gas and their entrapment in the rocks
at depth, a feature which manifests itself in the ‘nodding
donkeys’ pumping oil to the surface at places such as
Humbly Grove just to the north of the district.
Escarpment
Terrace (agriculture)
Geological survey
Cite
Citations (3)
Since the publication in 1840 of a brief but valuable memoir by J. D. Forbes, in which that author drew attention to “the traces of ancient glaciers” in the Cuillin Hills, that district has remained almost unnoticed by glacial geologists for half a century. This neglect is doubtless attributable chiefly to the difficulty of access to the mountains, a consequence of their peculiar configuration, which in turn is closely bound up with the glacial history of the district. The present contribution is the outcome of observations made during the years 1895–1900 in mapping the central part of Skye for the Geological Survey of Scotland. In traversing the mountains day after day throughout several successive seasons, the writer has been struck especially by the impressive evidence which they present of glacial erosion as the dominant factor in their sculpture, and to enforce this is the chief object of the present communication.
Ice caps
Cite
Citations (23)
T nHE two island archipelagoes, the Orkneys and the Shetlands, situated off the extreme north of Scotland, have been long a subject of interest and confused knowledge to those in the south. On account of their relative remoteness, particularly Shetland, little sound literature has been diffused. The two groups lie athwart the 59'and 60? N. parallels and consequently lie as far north as Cape Farewell (South Greenland), Kenai Peninsula (Gulf of Alaska), Okhotsk (Kamchatka Province), Leningrad, and Oslo. Such an aspect of the position (Figure 1 ) gives a very different impression from that in the usual atlas map of Scotland with these two countries placed into convenient sea areas off the Hebrides or Moray coast. Of the two groups the mid portion of Shetland lies more than a whole degree farther north thlla the central portion of Orkney and consequently is far more isolated than the latter as regards approach from the mainlland of Scotland. Orkney, within easy sight of Caithness (Figure 2), was as a result more easily settled by the ferry-loupers who crossed from the south and ousted the Norwegian settlers in the economic struggle. Both island groups consist of a large mainland, deeply penetrated by the sea, wvith associated satellite islands differing, however, in that Orkney has these scattered irregularly while in Shetland the islands are spread in a N-S line, if one includes Fair Isle and Foula, which is controlled by the geological structure trends. To the casual reader the two archipelagoes are considered alike, but a very cursory analysis reveals that the two are complementary in almost everything save position. As Figure 3 reveals Shetland consists essentially of a metamorphosed core with two main areas of warmer Old Red Sandstone soil-the west with which is associated Foula and the south with which is associated Fair Isle. In the west are areas of igneous rocks of either an intrusive or extrusive character. In the metamorphosed areas are certain limestone bands of outstandilng importance. They have proved to be weaker to erosion influences than the surrounding rocks and also have provided both less acid soils and a source of lime for sweetening soils elsewhere. These sheltered limestone valleys, as at Tingwall, have proved to be as valuable in the agricultural regime as the sandstone areas of Dunivossness in the south. By contrast with this the solid geology map of Orkney, Figure 4, reveals a monotonous stretch of Old Red Sandstone rocks save near Stromness where there is a development of igneous rocks and small outcrops of the Highland GraniteSchist-Complex. In other words, Shetlanld is to be placed with the Highlands of Scotland while Orkney is to be placed in the N. E. Coast Lands. The difference is further emphasized
Shetland
Cite
Citations (27)
The Appalachian Mountains of North America are traditionally considered to be the eroded roots of their original “Himalaya” size. The original heights are thought to have been erased by hundreds of millions of years of erosion resulting in the current rounded mountaintops, sediment filled valleys and rolling hills. Observations made along the Eastern Structural Front reveal categories of evidence that contradicts the idea of great age. The Appalachians are better explained as young formations created by recent catastrophic processes.
Appalachian Region
Cite
Citations (2)
As I shall be unable to be present at the reading of Mr. Geikie's paper on the Glaciation of the Outer Hebrides, I beg to submit to the Geological Society some extracts from my journals containing observations on the glacial phenomena presented by the western islands. Tiree , Sept. 1871.—The island is flat; and the low grounds appear to have been under water. The highest hill is Heynish, at the south-west end, and 500 feet high. On the top of the hill are a great many large perched blocks; some. are 14 or 15 feet long. So far as I could make out, they came from the north-west; they are chiefly gneiss, like rocks in the outer islands. The rocks are glaciated and weathered. Harris , Sept. 17.—The hills are made of contorted Laurentian gneiss, and much glaciated, but weathered. So far as I could make out, the ice came from N.N.W. throngh a gorge at Tarbet. Bernevay to Barra .—Bernevay is the last of the Hebrides; the whole chain looks like the hill-tops of a drowned continent. The separate islands are rocky and grassy, and are about 1000 feet high or less. On the east side these hills slope down to the Minch. On the west the Atlantic has battered the hills, and broken them, so that great cliffs now plunge sheer down, or overhang the sea. Where the rock is soft, the Atlantic waves dig into it, and make sea-caves, and there work mischief till the roof comes down. Then a
New Hebrides
Cite
Citations (6)