At 13 miles 70 chains the first of the deep cuttings begin, the bottom of the canal being 67 feet below the surface of the ground, and the strata is much less complex than along the estuary. It is near to this place that the canal leaves the waters of the Mersey, and takes an independent and almost direct course to its terminus.
From 15 miles, 50 chains to 16 miles there is again a very considerable alteration in the strata, the rock dipping sharply, and softer deposits coming in. At 15 miles 68 chains, where a bore was put down, no rock was encountered to a depth of 88 feet. Following along from 16 miles, where the bedrock rises, a fairly even contour of its surface is maintained, together with overlying strata of soil, sand, and gravel, to near 18 miles 20 chains, where the London and North-Western main line, and the Birkenhead, Lancashire, and Cheshire Junction railways are crossed.
From this point the surface rises gradually to 19 miles, opposite the Warrington Dock entrance, where the cutting is 50 feet deep. Near Warrington the existing river bed will be shortened by a cut-off and diverted from the course of the canal. At 21 miles 20 chains Latchford Lock is reached; the section through it is very similar to that in the preceding 5 miles. At 21 miles 70 chains the bedrock again disappears, giving place to a deep bed of quicksand and marl. The Mersey is twice crossed between 22 miles 10 chains and 22 miles 35 chains. There is another cut-off and diversion of the river near 22 miles 50 chains, where the bottom becomes soft brown sandy clay, and sludge, being in a bed 24 feet thick, which reaches 18 inches or 20 inches below the bottom of the canal; this runs into gravel and clay at 23 miles 10 chains, which again dies into a large bed of quicksand from about 23 miles 25 chains to 75 chains. At 24 miles 2 chains the rock is again struck by a bore at a depth of 12 feet below the bottom of the canal. The Mersey is again twice crossed at 23 miles 40 chains, and 70 chains, and the river is to be diverted through the existing channel, called the “Butchersfield Cut.” At 24 miles 20 chains the Mersey joins with the Bollin; from there the canal will become practically the river to Manchester, and the old river bed will be filled up. A sand and gravel formation continues to about 25 miles, where a bed of marl is reached, overlaid by hard and soft shale, but from the point where this runs out, about 25 miles 40 chains to Manchester, the canal follows more or less the bed of the river, wherein a much more complicated strata is met with than along the line of route which is away from the influence of the river, at between 14 and 25½ miles. Loam and streaks of sand, overlying hard red sand are met with from 25 miles 60 chains, to 26 miles 20 chains, where gravel and red rock come in, to 25 miles 15 chains, between which points the bottom of the canal by a strange coincidence follows almost parallel with the upper surface of the bedrock. At 27 miles 15 chains the rock dips and is not met with again for nearly half a mile. The Irlam locks are at 28 miles 50 chains; just at the entrance, rock again crops up and forms the bottom of the canal. At 29 miles a wedge-shaped layer of brown clay comes in which runs about half a mile, reaching a depth of 20 feet at the Manchester end; this suddenly ends in a deep bed of loam which it partially overlies—evidently it is a deposit from the river which flows above—then loam, sand, and gravel make the strata to about 29½ miles, when rock again appears, and runs almost to the surface at 29 miles 68 chains. At 30 miles 30 chains the rock runs out again from the bottom, and a heavy bed of loam, 36 feet deep, covers it, the cutting at this point being entirely in loam. A little further on, the rock bottom again rises, and from there sand and rock are chiefly met with to 31 miles 10 chains, where the rock dies out again, and blue loam comes in, forming a deep bed overlying sand, sludge, gravel and marl; near the Barton Locks this runs into heavy beds of loam near 33½ miles. At 34 miles soil, clay, and rock are the formations met with, each in nearly equal beds of 10 feet deep, until about 34 miles 50 chains, when much sand shows; at 34 miles 55 chains the bedrock dips, and sand over clay and loam form the strata to the terminal dock entrances at Throstle Nest. This completes the course of the canal proper.
The canal is to be constructed with a minimum width of 120 feet on the bottom. From Barton to the terminus, a distance of 3½ miles, the width on the bottom is to be increased to 170 feet; on the Salford side of this increased width of waterway, one mile of wharfage is to be built, giving a total length of 4½ miles of quay or wharfage frontage at the Manchester end, and leaving 2½ miles of frontage available for mooring lighters or vessels along this portion of the canal.
SECTIONS OF SHIP CANALS.
PANAMA CANAL
SUEZ CANAL