Let us note right away that the name GUYON was used, formerly indifferently, as a family name and as a first name for a man: in the first case, for example, the Guerin dictionaries recall a long list of people of letters and of liberal professions, national of many Provinces of France, since the Middle Ages.
 

As a first name, it is then used in connection with the father's family name, being analogous to the dominant mark of a given characteristic: such as that being the case of the ancestor of us Chiassons.  Which, must it be said, by no means would it only prevent a similiar qualifier going back to the preceding generations.
 

Anyhow, the word-first name of GUYON goes back to the old French of the Middle Ages, as the proof par excellence R. Grandsaignes d'Hauterive, in his Dictionary on page 342 where he writes Guion (or guyon) is a masculine name which means "guide", "chief", originating from the XIIth and XIIIth centuries. It is also used, of the period, as the verb "to guide", "to lead", "to command": all significances which indeed make a splendid setting!
 

Don't be surprised if one does not at all stop to guess why the nickname "Lavalle" which one no longer connects to the name of the ancestor and which hardly survives: if the interpretation is clear and fine, it seems nevertheless only to be attached to one's name in France, likely to distinguish it from neighbors of the same patronym but not of the same relationship.

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extract:  "Les Grands Arrangements Des Acadiens" by: Adrien Bergeron
 
 

Commentary: for those who will visit "Grand-Pre" in Nova Scotia, in "La Chapelle" which today is a museum, you will be able to see a monument where are registered, the names of the first newcomers in Acadia.  There one can see the name of Chiasson de La Vallee.  These bronze plaques on which appear the name Chiasson refer well to our ancestor Guyon Denis Chiasson.
 
 
 
 
 

Let us continue the step of the etymology of our surname CHIASSON which originates from the 15th century in a place called CAIXON, a commune of the High Pyrenees mountains, behind TARBES. The name Chiasson would be derived from the word CHIASSE, which describes metal foam.
 
 

Finally the conclusion of the surname of our family :
 

It is certain that our ancestors in France and Acadia would carry the name Chiasson and again today in France we find in the minitel (telephone book) the spelling Chiasson.  By studying more closely the parish registers, in that which concerns the descendents of Guyon Denis who made stock in Acadia, his sons Gabriel and Sebastien, we remark that their displacements were justified by the manhunt by the English delivering them. It was the grandchildren of Guyon Denis Chiasson who knew these difficult times.

Several grandsons of Guyon Denis knew of the exile, prisons and the deportation.  The massive deportation of Acadiens took place in 1755, but the exile for many began some years before. To try to escape the enemy, they abandoned their lands where they had been born. This escape lasted nearly 15 years during which we have difficulty following them because of frequent changes of place of residence.
 
 
 
 

We find them a little everywhere in the territory of old Acadia: in Cheticamp in Novia Scotia, in Rustico in Prince Edward Island, in Caraquet in New Brunswick, in St-Pierre et Miquelon, we find them also in Quebec: in Iles-de-la-Madeleine, in Gaspesie and on the two banks of the St-Laurent River.  For the most part the spelling of the name remains Chiasson.
 

However we often find in many registers the written name "Giasson" often due to the fact that some ancestors were illiterate and that the priests, signing the certificates of births, marriages and deaths were of English or Irish origin. Today we also find that the descendants of Gabriel and
Sebastien have the name "Giasson".
 

Therefore we can say that the descendants of Gabriel Chiasson and of Sebastien Chiasson had more populated the maritimes and the St-Laurent River in Quebec, whereas the descendants of Jean Giasson and Michel Giasson established themselves upstrean of the St-Laurent in Montmagny, Quebec and Montreal.