PEAT BOGS AND TURBARIES. 97 



rocks on points on each side of its course, carries with it 

 large portions of coarser matter, as stones, gravel, and 

 sands into the lower parts of a valley, and there deposits 

 tlie larger bodies first, then the smaller, and lastly the 

 finer, according to theii* respective densities, tili a Stratum 

 of alluvial matter id spread over the surface of the adjoin- 

 ing land which in time becomes fertilized in so high a 

 degree as to be almost inexhaustible ; and to this cause 

 also is to be attributed the level appearance of all these 

 marshes, as nothing but the action of water could have 

 caused their present level character. 



The rapid accumulation of alluvial deposit in any 

 Situation open to the influx of the tides of the Bristol 

 Channel, and not affected by a counter current, is 

 demonstrated by the filllng up of the original bed of 

 the river Brue, at Highbridge. The old channel was 

 abandoned in consequence of a new outlet being made, 

 about fifty years since, to improve the drainage of the 

 marsh above. This cavity was fiUed up in about 25 

 years, to a depth of nearly twenty feet, with the deposit 

 of the tide, and became cultivated land, producing fine 

 crops of corn. It was excavated again, and now forms the 

 entrance to the Glastonbury Canal navigation. 



The time required to effeet these changes is as nothing 

 in the calendar of nature, when measured by the Standard 

 of human calculation. Our own recollection is sufificient 

 to have witnessed the great change which has taken place 

 in tliese marshes in less than half a Century. When, there- 

 fore, we refer these considerations to a period of two or 

 three thousand years only, we see there has been ample 

 time for efFecting these changes on the earth's surface. 



Our ancestors, aware of the vast importance of protect- 

 ing this district from inundation by sea or land water, 



1853*. PART II. N 



