The Devon Minerals Plan (Proposed Adoption Version) tells us that:
5.4.6 Small quantities of marine-dredged sand and gravel are landed at Appledore and Yelland to serve local markets in northern Devon that are remote from the land-won sources in the east of the County.
But it turns out this is not the whole story. Thousands of tonnes of aggregate are being landed at Yelland Quay from Aggregate Industries' Glensanda quarry in Scotland.