Re: why do some farmers plant crops on hte slope of volcanoes?

Your question is a very common one.  
My students ask it every year and the 
answer comes in three parts.

1. One reason why people plant crops and live near the base of volcanoes is 
that, to the average person, a volcano that is not erupting looks like just 
 another mountain.  Remember that not all volcanoes erupt in a person's 
lifetime.  For example, before Mt. Saint Helen's erupted in 1980 (which is 
still erupting, but MUCH less violently), it hadn't 
erupted in close to a hundred years.  Mt. Rainier (which is closer to the 
BC border with Washington state)last erupted in 1882.  Mt. Garibaldi (which 
is just north of Vancouver) hasn't erupted in thousands of years.  So if 
you are a settler, a volcano that is not erupting looks just like another 
steep mountain.  Watch Mt. Rainier as the next possible MAJOR volcanic 
eruption on the West coast (according to the Decade Volcanoes list 
established by the United Nations).
  **check out the following website for a list of Canadian Volcanoes; 
http://vul
can.wr.usgs.gov/Volcanoes/Canada/framework.html    ****

2. Because volcanoes are relatively high, they collect a large amount of 
snow.  In the spring, this snow melts and provides a good source of water 
for people, plants, and animals to drink.  On a less scientific note, snow 
covered mountains are also pretty to look at and do attract tourists.

3. The volcanic soil is excellent for growing things.  It is very porous, 
which means that it can hold much more oxygen underground than other soils 
(which plant roots need) as well as being able to hold water (which plants 
themselves need) without drowning the roots.  The soil forms a natural kind 
of perlite.  Also, most scientists seem to agree (although there is little 
published on this matter) that volcanic soil is richer in the minerals and 
nutrients that plants need to survive than older soil.