@prefix locn: <http://w3.org/ns/locn#> .
@prefix geosparql: <http://www.opengis.net/ont/geosparql#> .
@prefix sf: <http://www.opengis.net/ont/sf#> .

<ex:a> a locn:Location ;
  locn:geometry [ a sf:Point ;
                    geosparql:asWKT "<http://www.opengis.net/def/crs/OGC/1.3/CRS84> Point(-0.001475 51.477811)"^^geosparql:wktLiteral ] .