Following a visit to Egypt in 1980–81, Riley created colours in what she called her 'Egyptian palette' and produced works such as the "Ka" and "Ra" series, which capture the spirit of the country, ancient and modern, and reflect the colours of the Egyptian landscape. Invoking the sensorial memory of her travels, the paintings produced between 1980 and 1985 exhibit Riley's free reconstruction of the restricted chromatic palette discovered abroad. In 1983, for the first time in fifteen years, Riley returned to Venice to once again study the paintings that form the basis of European colourism. Towards the end of the 1980s, Riley's work underwent a dramatic change with the reintroduction of the diagonal in the form of a sequence of parallelograms used to disrupt and animate the vertical stripes that had characterized her previous paintings. In "Delos" (1983), for example, blue, turquoise, and emerald hues alternate with rich yellows, reds and white.