diff --git a/LoopStructural/modelling/core/stratigraphic_column.py b/LoopStructural/modelling/core/stratigraphic_column.py
index 4f4eb003..48d5e084 100644
--- a/LoopStructural/modelling/core/stratigraphic_column.py
+++ b/LoopStructural/modelling/core/stratigraphic_column.py
@@ -668,7 +668,7 @@ def get_isovalues(self) -> dict[str, float]:
         surface_values = {}
         for g in reversed(self.get_groups()):
             v = 0
-            for u in g.units:
+            for u in reversed(g.units):
                 surface_values[u.name] = {'value':v,'group':g.name,'colour':u.colour}
                 v += u.thickness
         return surface_values
diff --git a/release-please-config.json b/release-please-config.json
index 3dbcbcb2..12d40ea0 100644
--- a/release-please-config.json
+++ b/release-please-config.json
@@ -15,11 +15,13 @@
     },
     "packages/map2loop": {
       "release-type": "python",
-      "component": "map2loop"
+      "component": "map2loop",
+      "release-as": "3.4.0"
     },
     "packages/loopstructural_visualisation": {
       "release-type": "python",
-      "component": "loopstructuralvisualisation"
+      "component": "loopstructuralvisualisation",
+      "release-as": "0.2.0"
     }
   }
 }
diff --git a/tests/unit/modelling/test_stratigraphic_column.py b/tests/unit/modelling/test_stratigraphic_column.py
index b10ed36e..1f7fc284 100644
--- a/tests/unit/modelling/test_stratigraphic_column.py
+++ b/tests/unit/modelling/test_stratigraphic_column.py
@@ -430,6 +430,20 @@ def test_get_isovalues(self):
         assert isovalues["B"]["value"] == 0
         assert isovalues["B"]["group"] == "Group_0"
 
+    def test_get_isovalues_multi_unit_group(self):
+        # Isovalues must match update_unit_values: the base of the oldest
+        # unit in a group is 0, and each unit's thickness gives the base
+        # value of the next (younger) unit.
+        column = StratigraphicColumn()
+        column.clear(basement=False)
+        column.add_unit("A", thickness=10, id=0)
+        column.add_unit("B", thickness=5, id=1)
+        column.add_unit("C", thickness=3, id=2)
+        isovalues = column.get_isovalues()
+        assert isovalues["A"]["value"] == 0
+        assert isovalues["B"]["value"] == 10
+        assert isovalues["C"]["value"] == 15
+
 
 class TestOrderingAndUpdates:
     def test_update_order_reorders_elements(self):