Sugarloaf mountains are commonly associated with the spectacular landscape of Rio de Janeiro with isolated steep-sided, dome shaped landforms rising dramatically above the vibrant city. Indeed, sugarloaf mountains are particularly abundant along the whole east coast of Brazil where they preserve fragments of the highly bio diverse, but largely unknown, mata atlantica rain forest across their distinctive steep slopes and isolated summits. With the mata atlantica already reduced to less than 7%1 of its original distribution due to deforestation, and many of its plants and animals endangered, understanding how the topography of the sugarloaf landscape contributes to the natural survival of these forgotten forests is exceptionally important to inform future conservation efforts across Brazil.

Sugarloaf Mountains: The Perfect Recipe for Rainforest Conservation?Miss Sarah Owen sco5@le.ac.ukDr. Dickson Cunningham, Dr. Kevin Tansey, Dr. Juan-Carlos Berrio: Departments of Geology and Geography

•To create a recipe for how Brazilian sugarloaf landscapes form through geological fieldwork in Pancas, Espirito Santo (Fig.1)• To establish the environmental significance of this unique landscape in preserving precious rain forest fragments using satellite imagery and ecological field studies

3. The Geology of the Brazilian Sugarloaf Landscape

•The sugarloaf landscape of Pancas is composed of a large metamorphosed granite intrusion.• Regional north-north-west fractures cut through the granite causing weaknesses within the landscape observed as long linear valleys and sugarloaf wall incisions (Figs. 2 and 3).•Fractures result from crustal stresses during the separation of Africa and South America to form the Atlantic Ocean, 65 Million Years Ago2.

4. Geological Synthesis: The Recipe for a Brazilian Sugarloaf Mountain

Ingredients:•A strong resilient igneous or metamorphic landscape e.g. Granite that will withstand many thousands of years erosion

•“Fork Scouring” regional fracturescausing weaknesses within the rock

•Hot tropical weathering to eat away at the rock in the subsurface and form a laterite covering (soft, rotten granite).

•Onion skin exfoliation to shed the sugarloaf’s granite skin on exposure

Cooking time: The age of the Brazilian sugarloaves is still unknown. Sugarloaves in Australia indicate a possible age greater than 2.5 Million Years3.Landscape serves: 383 of 633 endangered species and supports 711 endemic species (found only in Brazil)1.

Method:

1

Figure. 1 Locality Map and View of Sugarloaf landscape in Pancas Valley

Fracture = Weakness

5. Sugarloaf Mountains and the Conservation of the Mata Atlantica

Field Results:The formation of the Brazilian sugarloaf landscape has created a safe haven for the animals and plants of the mata atlantica rainforest. In Pancas, many of the remaining forest fragments were observed to lie across four key topographic settings: Summit, Shoulder, Collar and Valley Floor (Fig.3).

6. Future Work:•Measure the density and height of the forest canopy across the different forest sites to document variations in floral richness.•Assess the connectivity of forest patches to highlight importance of protecting the vulnerable valley floor forest fragments.

References: 1. SOS Mata Atlantica Official Publication “Mata Atlantica” 2008. 2. Chang et al. 1992. Tectonics and Stratigraphy of the East Brazil Rift System: an overview. Tectonophysics, 213. 97-138. 3. Bierman et al. 1995. 10Be and 26Al Evidence for exceptionally low rates of Australian bedrock erosion and the likely existence of Pre-Pleistocene landscapes. Quaternary Research 44, 378-383. 4. Thomas, M.F. 1978. The Study of Inselbergs. Zeitschrift fur Geomorphologie Supplementary Band 31. 4-41.

•Summit and Shoulder forests are isolated, perched on the high steep slopes of the sugarloaf. These forests survive in a harsh hot environment with little soil, nutrients or water. They are host to a vast array of specialised vegetation.

Figure 3. ASTER False Colour Map showing the distribution of mata atlantica (dark red) across the linear valleys and peaks of the sugarloaf landscape.

Collar

Shoulder

Valley Floor

2. Aims

BRAZIL

RIO DE JANEIRO

PANCAS

5 The Resultant Sugarloaf form:Summit

Discussion: Are Sugarloaves the perfect recipe for mata atlantica conservation?

Yes:•Sugarloaves provide an isolated safe haven away from human destruction.•Summit forests show vast array of specialised vegetation only found in Brazil which have adapted to survive the harsh conditions.

No:•Sugarloaves divide up the landscape placing the more diverse valley floor forests within easy reach of humans.•Forests are fragmented, decreasing the ability for animals to move.

•Collar and Valley Floor forests are more diverse, with a thick, full tree canopy. The lower elevations have a rich supply of water and soil to support the tall trees but are easily disturbed by human activity shown through abundance of the fast growing silver leaved tree Cecropia Hololeuca (Fig.4).

Acknowledgements: Thank you to the generous donations of field work funding from The Jeremy Willson Charitable Trust, The Royal Geographical Society, The Geological Society of London and Santander.

Figure 4. Silver leaves of Cecropia Hololeuca signify areas of disturbed ground

Figure Modified from Thomas (1978)4

1. Background

Figure 2. Rose diagram and photo to show dominant north-north-west fractures in the Pancas sugarloaf landscape

Shape is initiated in the subsurface in region of little or no fracturing

Weaknesses created by a fracture become exploited by tropical

chemical weathering

Laterite

Erosion is captured and accentuated at base of

gentle slope

Limited exfoliation continues around

the summit

Granite

Key Point: Landscape lowering produces the mountainous relief

2 On exposure:

3

4

Exfoliation on peaks and sides

of sugarloaf cause slopes to

steepen

Removal of debris at base through captured valley

erosion

Weathering and erosion remain focused within the valley floor, creating steep

sugarloaf walls

Exfoliation sheets begin to

form due to pressure release

0 1km