I'm afraid that Ricardo is right, you can find examples of "intrusives" in the literature. Unfortunately this is due to bad editing and the fact that not all geologists have a profound knowledge of grammar. :( "Intrusion" is a noun and can be plural; "intrusive" is an adjective and can never take an "s". Below are two examples of correct usage. :) <P>-<P>
Earth Science World Image BankGranites; Intrusive Rocks; Metamorphic Rocks; Plutonic Rocks, This granite intrusion still supports the remainder of the overlying metamorphic layer. ...
www.earthscienceworld.org/images/search/results.html?Keywor... - 40k -
<P> -<P>The nature of intrusive memories after trauma: the warning signal ...Individuals who had experienced a range of different traumas were asked to describe the quality and content of their intrusive memories. Visual intrusions ...
www.accelerated-learning-online.com/research/nature-intrusi... - 20k - Cached - Similar pages