HA RD WICKE'S S CIENCE- G OS SI P. 



199 



Here it is very flat, the tide going out so far tliat one 

 hardly expects it to come back again ! A strong 

 westerly wind brings up the sand in great force. It 

 is very singular to see it travelling like streaks of 

 smoke over the flat wet shore. The wind denudation 

 often cuts away the sand of the shore to perhaps 

 2 inch deep, leaving little protuberances of the form 

 of a thorn wherever there is a shell or shell fragment 

 to protect it. These I described in the " Geological 

 Magazine" {1875, PP- 5S7-8) under the name of 

 "eolites." Some of these sandhills are very recent, 

 for we find, not far from their base, interstratifications 

 of cinders and matter thrown up from wrecks. 

 Further inland it is surprising how few shells there 

 are in the sandhills ; I imagine they must decay from 

 the percolation of water. I have made many excava- 

 tions for houses and sewers and had abundance of 

 opportunities of observing, and these are my expe- 

 riences. The folly of building houses upon sand has 

 been proverbial these nineteen hundred years. Here 

 the folly is perpetrated every day I I have erected 

 large houses with heavy walls actually upon sandhills, 

 without settlement ! The fact is that siliceous sand is 

 one of the most incompressible of substances. The 

 Truant Industrial School of the Liverpool School 

 Board at Hightown, of which I was the architect — a 

 heavy building — is erected upon blown sand which 

 lies on a bed of peat underlain by fine silt. Part of 

 these foundations were as soft as gruel, through 

 saturation with water. Below a certain level, which 

 fluctuates according to the season and rainfall, the 

 sand is universally quicksand, and in putting in 

 sewers it is necessary to close pile the trenches. 

 Saturation with water makes the previously hard, 

 dry sand into quicksand, which will run through a 

 very small opening. 



Vegetation, such as dwarf willows, often protects 

 patches of sand from denudation, leaving them as 

 islands standing in a denuded plain. 



Although some of the sandhills are so recent, the 

 whole of the blown sand must have taken a long 

 time to form ; it is 22 square miles in area to 16 lineal 

 miles of coast. It is impossible to make anything 

 like an exact calculation, but from observations of 

 the accumulation of sand during many years on 

 measured plots facing the sea, with every condition 

 favourable for its accumulation, I estimate that it 

 must have taken not less than 2,500 years for the 

 whole of this sand to accumulate, but probably much 

 more. I purpose laying these details before the 

 public at a future time.* 



In places the wind simulates the ripple-marks of 

 water in the moving sand. Under the microscope there 

 is no appreciable difference in the roundness of the 

 grain between the sand of the shore and that of the 

 sandhills, 



* This has now been done in my paper " The Date of the 

 Last Change of Level, Lancashire," and the next number of 

 the "Quarterly Journal of the Geological Society "will, I 

 expect, contain the figures and details. 



Water Supply. — The mode of obtaining water for 

 supplying the houses, where they are not as in many 

 cases connected with the town main, is by shallow 

 wells. The practice is to sink a well about five feet 

 diameter as deep as the seam of sand at the bottom 

 will allow, which as a rule is not more than five or six 

 feet below the line of saturation. If the well is kept 

 constantly pumped from day to day the water is clear 

 and good, but if allowed to remain stagnant without 

 pumping, it becomes more like rotten eggs from 

 the sulphur in solution. The circulation of the water 

 in the sand is of a very simple nature, the sand 

 forming an extended sponge. In the New Red 

 Sandstone, on the contrary, a well usually draws its 

 supply from a much larger area through the tapping 

 of fissures which act as ducts, carrying the water 

 sometimes, in the case of deep wells, for miles,* 

 Still the sand contains a great deal of water in its 

 interstices, and in the case of a sewer I constructed 

 entirely in it, about a mile long and about twelve feet 

 average depth, the subsoil water was constantly 

 running ; of course the amount fluctuated, but it never 

 ceased even in the dryest weather. 



Chemical Action. — All drainage from the sand 

 deposits a flocculent ochreous precipitate. The 

 " Links " of the West Lancashire Golf Club are 

 intersected in places with open drains, and this de- 

 posit of flocculent ferric oxide is a great trap for the 

 golf balls, which once in cannot be found, to the 

 great benefit of the professional ball-makers. Like 

 the "burn" at St. Andrews it is the ball-makers' 

 providence ! Rain water contains a small quantity 

 of carbon dioxide in solution ; the ferric oxide coating 

 the grains of sand, probably previously converted 

 into ferrous oxide by decaying vegetation, is washed 

 out by the percolating water, which on exposure 

 loses its carbon dioxide, and is precipitated again 

 as a flocculent ferric oxide. The water from the 

 sand is also hard, showing that it has taken up lime 

 in solution. When peat lies upon sand, the sand is 

 universally white, from the irca being discharged 

 through the chemical action, according to M. Julien, 

 of the Humus acids. f 



Sea action : Coast erosion. — Through certain altera- 

 tions in the currents and channels of the estuary, 

 prevalent winds, etc., the line of coast erosion changes 

 from time to time. The deposits of sand formed by 

 wind action gets eaten into at places, while at others 

 the land grows out seawards by accumulated wind 

 drift. It appears as if the land were really a constant 

 quantity ; what is taken away here is deposited there. 

 This erosion produces, for the time being, precipitous 

 cliffs of sand, showing the internal stratification of 



* See my report " On the South Lancashire Wells," British 

 Association Report, on the circulation of underground water, 

 1S77. 



t " The Geological Action of the Humus Acids," by Alexis 

 A. Julien, "Proceedings of the American Association for the 

 Advancement of Science," Vol. XXVIIL, Saratoga Meeting, 

 August 1879. 



