<P> The snow used to build an igloo must have enough structural strength to be cut and stacked appropriately . The best snow to use for this purpose is snow which has been blown by wind, which can serve to compact and interlock the ice crystals . The hole left in the snow where the blocks are cut is usually used as the lower half of the shelter . Sometimes, a short tunnel is constructed at the entrance to reduce wind and heat loss when the door is opened . Snow's effective insulating properties enable the inside of the igloo to remain relatively warm . In some cases, a single block of clear ice is inserted to allow light into the igloo . Animal skins were used as door flaps to keep warm air in . Igloos used as winter shelters had beds made of ice and caribou furs . These' ice beds' are unique to the region and Inuit culture . </P> <P> Architecturally, the igloo is unique in that it is a dome that can be raised out of independent blocks leaning on each other and polished to fit without an additional supporting structure during construction . An igloo that is built correctly will support the weight of a person standing on the roof . In the traditional Inuit igloo, the heat from the kudlik (qulliq, stone lamp) causes the interior to melt slightly . This melting and refreezing builds up a layer of ice that contributes to the strength of the igloo . </P> <Ul> <Li> Igloo construction </Li> <Li> <P> An igloo side view diagram; opening to the right, the optional window may be composed of an ice block </P> </Li> <Li> <P> An igloo's snowbrick laying method </P> </Li> </Ul> <Li> <P> An igloo side view diagram; opening to the right, the optional window may be composed of an ice block </P> </Li>

What type of houses did the creek live in