Iso-Horila Hill aka Horilankero
The measurement point of the Horilankero is nowadays known as Iso-Horila or Horilanvaara. It is located about 20 kilometres northeast of the municipal centre of Ylitornio, on the western side of the village of Ratasvuoma.
The top of the hill is heavily wooded. At the top is a bolt drilled into the rock, which acts as a land survey anchor point and is surrounded by lush vegetation.
On the eastern side you can see the houses and fields of Ratasvuoma – otherwise the views from the top of the hill are dominated by forests.
Iso-Horila Hill is the central point in Maupertuis’ chain of survey triangulations – all triangles in the chain end up there, forming a heptagon around Iso-Horila.
The scientists used the heptagon to check their chain of triangles. The sum of the angles of a planar heptagon had to be 900 degrees. The sum of the angles of the heptagon on a curved surface such as the Earth had to be greater than 900 degrees. The angle measured by the expedition was 900° 1′ 37”.
The expedition left Iso-Horila on 18 August, after spending five days there. The next day they saw from Aavasaksa that the hill was on fire. A carelessly extinguished campfire had ignited a forest fire. Maupertuis sent 30 men to fight the fire. In addition to the forest, the fire destroyed a marker erected on the hill.
Pedre, the expedition’s French servant, knew the exact location of the marker, and with his help the marker was re-erected. A number of men were left on standby in case a fire broke out again.
The Iso-Horila forest fire also disrupted measurements at other points in the chain of triangles. For example, the southern point of the baseline in the village of Niemi (or Niemis) and Huitaperi Hill had difficulties due to thick smoke that reduced visibility.
Iso-Horila rises next to the open mire and field landscape as a high, forest-dominated hill. On its slopes are extensive rock outcrops and ancient shorelines dating back 10,000 years, but they are not visible in the surrounding landscape because of the forest cover of the lower slopes.
Like Aavasaksa Hill, Horilankero is a moraine-domed hill. After the last Ice Age, the peaks of the highest hills remained as islands. These hills are referred to as domed hills because the ancient waters did not wash away their moraine cover.
The domed crown of Iso-Horila is about 400 metres long and 200 metres wide. The top of the hill is covered by a primeval-like spruce forest, and the landscape is enclosed.
There is a small private nature reserve in the Iso-Horila rock area.
Sources:
Husa, Jukka ja Teeriaho, Jari. Luonnon- ja maisemansuojelun kannalta arvokkaat kallioalueet Lapissa. Suomen ympäristö 6/2015. Ympäristöministeriö, Suomen ympäristökeskus. Helsinki, 2015.
Maupertuis, Pierre Louis Moreau de. “Maan muoto”. Maan muoto ynnä muita kirjoituksia Lapista. Ed. Osmo Pekonen. Väyläkirjat, 2019 (orig. 1738).
Outhier, Réginald. Matka Pohjan perille. Maupertuis Foundation and Väyläkirjat, 2011 (orig. 1744).
A map
Guidelines for using the map
- Red = Measurement point of the triangulation chain.
- Green = Walking route.
- Blue = Arrival from the main road (highway 21).
- Markers: Tap or click to get more information about the destinations.
- Zoom out: Shows the location in the triangulation chain.
- Drop icon: Locates the user’s location on the map.
- Measure tool: Measure distances between locations.
Open the map in a new browser window.
On the old map
Iso-Horila on the map drawn by Réginald Outhier (Carte du fleuve de Torneå, 1736).

Information
Pictures from Iso-Horila
The pictures open in large size in the gallery by clicking on the picture.

The expedition on the map
Réginald Outhier has written a detailed description of the expedition’s journey from Paris to Tornio and back. The journey took two months each way and was made by boat and wagon. On the way back, the expedition was in a shipwreck in the Bay of Bothnia.
Measurement points and other destinations
- Aavasaksa
- Baseline
- Huitaperi
- Kaakamavaara
- Kittisvaara
- Niemivaara
- Nivavaara
- Pullinki
- The Church of Matarengi
- The Church of Tornio
- The rapids of the Torne