Thetis Island Shoreline Mapping

Extracted text (beginning)

THETIS Is.
DATE:  10/25/11
Refer to Islands Trust Report “Gulf Islands Shoreline Mapping - Project Methodology” July, 2011 for detailed map information. 
1 Km
/
Islands Trust
Preserving island communities, culture and environment
MAPPING PRODUCTS PRODUCED BY:    Murdoch de Greeff Inc. (Project Lead) | Coastal and Ocean Resources Inc. | Archipelago Marine Research Ltd. | Land & Water Inc.             IN PARTNERSHIP WITH:    UBC School of Architecture and Landscape Architecture  and the  Islands Trust.
PROJECT FUNDING GENEROUSLY PROVIDED BY:  
Rock (Hard) ShorelinesSediment (Soft) Shorelines
MARSH/FINE SEDIMENTPEBBLE/SANDBOULDER/COBBLEBLUFFLOW ROCK/BOULDERSEA CLIFF
structurally altered*
Sections of shoreline 
with significant 
structural alterations 
(>30% altered)
LEGEND: 
*Shorelines 
modified 
by facility 
development, 
principally boat 
ramps,  seawalls, 
riprap, landfills, 
piers, groynes, or 
breakwaters.
THETIS ISLAND: 
2.2 Km (8.3%) of 
Structurally Altered  
Shoreline
DATE:  June 30, 2011
Re fer to Islands Trust Report “Islands Trust Shoreline Mapping  
Project Methodology” July, 2011 for detailed map information. 
• rocky shore with 
low slopes
• 49% of shoreline   
(13 Km)
The Thetis Island shoreline is largely bedrock and relatively stable.  The geology of the island dic-
tates that more sea cliffs occur on the east side of the island, while low-rock boulder shores are 
more common on the east side.  There are a few small sand pocket beaches, some made of shells. 
Although few in number, these pocket beaches are distinct features on the shoreline.   
The protected channel between Thetis and Penelekut Islands is the site of Thetis’s only signifi-
cant saltmarsh and mudflat, a function of sediment and nutrient inputs from watersheds draining 
into the channel, and longshore currents transporting sediment along the Penelekut Island 
shoreline into this ecologically important area.  Cufra Inlet, the long narrow inlet on the 
north shore, is very protected from wave energy, and likely sensitive to waterborne 
pollutant accumulation from land-based activities (i.e.: fertilizers and septic field dis-
charge).
pebble / sand
low rock/boulder
sea cliff
boulder / cobble
marsh/fine sediment
• stable or accreting 
pebble-sand (or shell) 
beaches (may be 
eroding where sediment 
supply is interrupted).
• 4% of shoreline (1 Km)
• rocky shore with 
steep slopes
• 21% of shoreline    
(6 Km)
• boulder - cobble 
cover on beach (often 
eroding upland)
• 22 % of shoreline       
(6 km)
• low energy shorelines 
with sediment inputs 
from watersheds 
nearby
• 4% of shoreline (1 Km)
• moderate to high 
slopes of sediment 
(often eroding)
• Thetis Island has no 
bluff shores
1 Km
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MAP 1 of 3:   Distribution of Shoreline Types
Watershed Boundaries
Drainage Conveyance Zones
(wetlands, creeks & moist 
soil areas)

THETIS Is.
DATE:  10/25/11
Refer to Islands Trust Report “Gulf Islands Shoreline Mapping - Project Methodology” July, 2011 for detailed map informatio

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