What is the reference point for lines of longitude?

Aletsch glacier is the largest glacier in switzerland and the largest found in the alps, a mountain range which extends from monaco in the east to slovenia in the west. currently, the aletsch glacier is retreating. under what circumstances would this glacier see growth instead of retreat? a decline in plate tectonics across the mountain range annual snowfall that exceeds yearly losses an increase in ablation in the southern valleys a rise in temperatures to that of a mediterranean climate

Witch of the following volcano hazards is made up of rocky particles about the size of a grain of sand

When volcanoes erupt, magma (hot, molten rock) rises toward the surface of the earth. as magma cools, solid rock forms. this rock contains substances from the interior of the earth. which of the following natural resources is likely to be plentiful near subduction zones where volcanic activity has occurred in the past?