Micrograph of the Month: Medieval floors

This is the second floor themed micrograph post, you can see examples of Neolithic floors in a post from last year here. You'll notice the same horizontal surface and distinct boundaries, and even a similar type of charred plant, ash and bone debris, however the construction of the floors themselves is quite different. Whereas the prehistoric floors are made from packed mud/earth, these Medieval floors from the town of Riga are made from a calcareous material with a very high quantity of sand grains. It looks very similar to a lime mortar, though I want to do a bit more work on it before saying that for definite.
Another difference here, whereas the Neolithic floors were showing signs of post-depositional processes in the form of gypsum crystals, the debris on this floor is remarkably well-preserved.
I have put together two photos here, the bottom image showing an earlier floor, overlain by mixed debris, containing tiny bone fragments, wood charcoal and ash. The upper photo shows the same debris layer and the second, later floor constructed on top. The floors themselves are about 45mm thick. The debris layer is very fine, only about 5 mm, yet can give us insights into the types of activities that were occurring here.This is part of the same set of samples I discussed in December, from a different part of the site.