“However, in addition to that alluvium much of central Belfast is underlain instead by a deposit of soft grey mud, silt and fine sand with numerous sea shells, in particular oysters.”

“The environmental effects of careless logging have led to soil erosion, polluted rivers, siltation and severe flooding.”

“The objective is to minimise poaching, overgrazing and soil erosion as this can lead to siltation and nutrient enrichment of surface waters.”

“Swan mussels are highly sensitive to siltation and other environmental changes.”