A Run To The Lakes: Borrowdale.

approach to the nature of the igneous rocks . To these the title of metamorphic rock is assigned . * These metamorphic rocks , however , as well as the vast chains of granitic and igneous rocks , are for all economical purposes next to useless , and the great mass of the sandstone , unless

it be on the outskirts of the great field of clay slate , is unfit for building purposes . The few specimens we collected and examined , such as those from Tallantire , Lammonby , and a portion of the old red sandstone from Bag-grow , were coarse in the grit , and very friable ; although we have seen excellent specimens from the quarries of Cockermouth on the one hand , and Penrith on the other .

The clay slate , therefore , is the rock of greatest importance in the central Lake districts . In the original Cumbrian group of Sedgwick , it is divided into three great generic classes , as follows : —

1 . Hornblendic clay slate ( lower ) . 2 . Chiastolite slate ( middle ) . 3 . Clay slate proper ( upper ) . The first rocks are of a uniform argillaceous character , except where the veins and their l-amince

of quartz diversify their aspect ; or where igneous rocks change their textures . The colour is usually dark , the surface glossy , and the mass irregularly laminated . They are more or less characterised by what is known as slaty cleavage . The boundaries of the district occupied by middle

slates are on the north-west line from Egremont to Keswick . The face of the whole mass , as seen on Derwentwater , about Barrow , is a red , mottled , argillaceous rock , usually regarded as a breccia . The colour being considered accidental , we find similar brecciated structures and various grey tints

among the rocks at the entrances of Borrowdale , around the north side of Grasmere , ancl other places . A close scrutiny of the circumstance under which the rocks are associated suggests the idea of their being in part aggregates of volcanic mud and submarine streams of felspathic lava .

The ivpper slates , clay slate proper , or , rather , as they are termed , micaceous flags and slates , correspond in some parts of the series with the upper Ludlow slates and tile-stone beds of Shropshire and Caermarthenshire . In some places they yield excellent roofing-slates . As represented by

the Kirby group , they somewhat resemble the flags of Llandeilo , in South Wales ; or still more closely , as Professor Sedgwick has pointed out , the flags of Denbighshire , in North Wales . This sketch will probably be sufficient to show that the economic geology of the district is chiefly

concentrated in the groups of clay slate . It is these rocks which , on disintegration , yield the rich clayey soil of the valleys . From these rocks are also derived nearly the whole materials for building , from the pavement-flags to the roofing-slates , from the lintels and janibs to the rouble and the

road metal . As to the analogous groups of finegrained grey or green slaty rocks , as well as those porphyries which seem to be composed of indurated , argillaceous matter , we must in the mean time refrain from describing them ; but they are all to be referred in their geological classification

to one or other of the above groups . We strongly recommend all persons interested in the physical aspects of the country to take a ride up by Derwentwater , through Borrowdale . Thither we went , partly for the purpose of seeing that dreary valley ( of which it may be mentioned

that Earl Eussell said , not long ago , that it was the most magnificent prospect in the district ) , partly to study the rocks , and also partly to inspect the village of Seathwaite , which , as we all know , is celebrated in modern story for its heavy rainfall . The first thing worth noticing is the

waterfall at Lodore , which is chiefly remarkable for the enormous chasm that the water has worn through the rocks . After passing through the "Jaws of Borrowdale , " as the entrance to the valley is not inappropriately termed , we ascend by one of the narrow and precipitous roads so

common in the district to the quarry of Queyfoot , in which the " schistus" clay-slate is extensively worked , and altogether , it would seem , from the surface . From this quarry most of the buildings in Keswick and the neighbourhood are supplied . Further on we arrive at the celebrated " Bowder

Stone , " an immense block of basaltic green stone , which has evidently broken away from the overhanging cliff , and has been computed to weigh nearly 19 , 000 tons . Nearly opposite this "bowder " we observe the Castle Crag , famous as the site of a Eoman fortification ; and from this crag the

view up Derwentwater , under a favourable aspect , is unapproachably beautiful . There is the calm and placid surface of the silent lake , the majestic hills which rise in graceful and irregular slopes on either side , the green islands , the jirojecting crags , the vapoury clouds , and the rich sunny

hues" That gild with yellow radiance all the vale . " Such a picture one seldom sees and long remembers . But , to turn again to Borrowdale , the geologist may easily observe the green mounds , covered with boulders of transported rocks , which

mark the place where the glacier of a former period had melted away and deposited its burden . A more practised eye will also detect the surfaces of the striated and polished rocks , which record at once the character and the direction of a force which , as Agassiz has detected in our time , is still at work among the glaciers in the Alpine regions of Switzerland . After passing the pretty