Could anybody suggest any information or references on the activity related to iron smelting located on the island of the lake or river? From any period and country?

Last year we had small excavation with 10 m2 area uncovered on the lake island site, which is small 200x40 m glacial hillock with clayed till covered by sand and sandy loam. App.150 kg of iron slag and pieces of clay furnace (-es) was found. The material concentrated on the highest spot of the hillock at 2-3 m above the lake level and chosen area for excavation was the most anomalous spot according to magnetic susceptibility data. The material was mixed with clear sandy loam with no observable stratigraphic layers. The thickness of homogenous sandy loam layer varied, the clay bottom in the trench was reached at the depth of 0.9 m, and the contour of this bottom resembled the zone as if mining activity might has been performed for extracting clay material for the furnace built nearby. However, no intact furnaces or other structures of manufacturing were found as well as no traces of charcoal. The iron slag itself is analogous to those sites dated to the Roman Period in the East Baltic region.

Currently available information suggests the site to be the place not for iron smelting but rather the place for burying the debris of iron manufacturing?!

I would appreciate any comments and remarks on this situation.