Scoria cones
The major volcano of Madeira is the island itself, Madeira is a shield volcano. Although greatly eroded, its shield shape can still be recognized when the island is observed from a distance. But the island itself is not the only volcano shape that can be seen in Madeira.
Scoria cones are other volcanic geomorphological features that can be seen on the island. Most of these smaller volcanoes occur on the flanks of Madeira island, closer to the sea, but they can also be found on the island plateau in a more central area. Some of the places where they can be seen are Porto Moniz, Funchal, Caniço, Ponta de São Lourenço and Paul da Serra.
Scoria cones (or cinder cone) are the smallest type of volcano (see image below), usually with heights less than 300 meters, frequently occurring in groups on basaltic lava fields on the flanks of larger volcanoes.
Scoria cones have the form of a conical hill with very steep slopes. The tephra accumulates as pyroclasts deposit around a vent forming the volcanic edifice. Scoria cones are often symmetric preserving a central crater at the top. If this crater was breached the remaining walls can form an amphitheater shape around the vent.
Types of volcanoes:
These scoria cones were built up in the later stages of volcanic activity. They belong to the “Upper Volcanic Complex” (See the Geologic Map of Madeira where they are represented in whitish colors). Because they are more recent than the rest of the volcanic edifice, they were less affected by erosion, so some of them are in fact very well preserved.
Scoria cones in Funchal
Funchal is one of the best places to see these small volcanoes. They are right in the middle of the city, occurring along a NW-SE alignment which is thought to be a major fissure (volcanic activity in Madeira was fissure type) along which scoria cones developed [1]. In the following photo you can see the volcanic cones of Pico da Ponta da Cruz, Pico de São Martinho, Pico da Igreja de S. Martinho, Pico dos Barcelos and Pico das Romeiras. Most of them have buildings on top:
This is the location of the cones in an aerial image (Google Earth):
Western and eastern views where you can try to spot them yourself:
Closer photos of the scoria cones:
This cone of “Pico da Ponta da Cruz” was considered to be the cone where the last eruption took place in Madeira [2]. Now, the last eruption is attributed to Paul da Serra, about 7000 years ago.
Submarine cones
A linear chain of conic seamounts of volcanic origin were recently located to the south of Funchal. Its exact relation to the Funchal cones is not known yet [3].
References
[1] Silveira, A. et al. (2010). Notícia Explicativa da Carta Geológica da Ilha da Madeira, na escala 1:50000. PDF
[2] Prada, S. (2000) Geologia e Recursos Hídricos Subterrâneos da Ilha da Madeira. PDF
[3] Geldmacher, J. et al. (2006) A geochemical transect across a heterogeneous mantle upwelling: Implications for the evolution of the Madeira hotspot in space and time. PDF