whereupon

Does the following sentence sounds correct?

The own and original creation of the author predominates on the mere reproduction; the works are unusual, creative, original and astonishes the rapidity whereupon they are developed and they evolved.

why don't you try starting with:

"The author's own creation..." (you might want to ommit "original" here since you're using it in the 2nd clause...)

Help me out a little more, Solfinker, and then I'll do my best:

predominates on the mere reproduction----¿Qué quieres decir con esto?
y también: astonishes the rapidity ? asombra la rapidez?

Be careful with subject/verb agreement: the works astonish / the work astonishes

Maria:
The rapidity astonishes.

The author's own creation (thanx victoria) predominates on the mere reproduction means that art is more important than productivity (art for art's sake?)

Thank you once again for your help.

Are we talking about one piece of art or many pieces of art?

The author's original creation outshines the the reproduction. The original works are unusual, creative, and original and the speed with which they are developed and evolve is astonishing.

This still feels redundant and a little confusing to me in terms of singular/plural. How about:

The author's original creation outshines reproductions of his works. The original works are unusual and unique, and they are produced with astonishing speed.

the works are several pieces of art.

I don't like they are produced with astonishing speed. since the speed here refers to the evolution and improvement.

Thank you.

So maybe:
The author's original creations outshine...

I would need still more context. I'm still not clear on what it's supposed to mean:

Evolution and improvement of theme (or something else) from one work to the next in the series?
Evolution and improvement of each work as it is produced?

Solfinker I greet you.

Is this a translation from spanish? I might be able to help if I knew the country of origin of the sentence.

Hello!
Yes, it's a translation from Spanish (Spain). Here is the original sentence:

El fauvismo, el cubismo y el expresionismo que evolucionaron hacia al surrealismo, neorrealismo, expresionismo abstracto, Op Art y Pop Art, entre otros numerosos estilos y escuelas artísticas, han configurado la historia del arte de este siglo. Predomina la creación propia y original del autor sobre la mera reproducción; las obras resultan insólitas, creativas, originales y asombra la rapidez con que se desarrollan y evolucionan

How about this:

Individual and original creation predominated over mere reproduction. As a result, the works are unique, and the speed of this development and evolution is astonishing.

Great! No whereupon needed!