The dry mountain ranges of the Western united states contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life. This rock record provides clues about one of the most significant radiations (periods when existing life-forms gave rise to variations that would eventually) evolve into entirely new species) in the history of marine invertebrates. During this radiation the number of marine biological families increased greatly, and these families included species that would dominate the marine ecosystems of the area for the next 215 million years. Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation. And , in fact, there is evidence of major ecological and geological changes during this period: the sea level dropped drastically and mountain ranges were formed, in this instance, rather than leading to large-scale extinctions, these kinds of environmental changes may have resulted in an enriched pattem of habitats and nutrients, which in turn gave rise to the Ordovician radiation, However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood.

Line	In current historiography, the picture of a consistent,
	unequivocal decline in women’s status with the advent
	of capitalism and industrialization is giving way to an
	analysis that not only emphasizes both change (whether
(5)	improvement or decline) and continuity but also
	accounts for geographical and occupational variation.
	The history of women’s work in English farmhouse
	cheese making between 1800 and 1930 is a case in
	point. In her influential Women Workers and the Industrial
(10)	Revolution (1930), Pinchbeck argued that the agricultural
	revolution of the eighteenth and early nineteenth
	centuries, with its attendant specialization and enlarged
	scale of operation, curtailed women’s participation in
	the business of cheese production. Earlier, she
(15)	maintained, women had concerned themselves with
	feeding cows, rearing calves, and even selling the
	cheese in local markets and fairs. Pinchbeck thought
	that the advent of specialization meant that women’s
	work in cheese dairying was reduced simply to
(20)	processing the milk. “Dairymen” (a new social category)
	raised and fed cows and sold the cheese through
	factors, who were also men. With this narrowing of the
	scope of work, Pinchbeck believed, women lost
	business ability, independence, and initiative.
(25)	Though Pinchbeck portrayed precapitalist,
	preindustrial conditions as superior to what followed,
	recent scholarship has seriously questioned the notion
	of a golden age for women in precapitalist society. For
	example, scholars note that women’s control seldom
(30)	extended to the disposal of the proceeds of their
	work. In the case of cheese, the rise of factors may
	have compromised women’s ability to market cheese
	at fairs. But merely selling the cheese did not
	necessarily imply access to the money: Davidoff cites
(35)	the case of an Essex man who appropriated all but a
	fraction of the money from his wife’s cheese sales.
	By focusing on somewhat peripheral operations,
	moreover, Pinchbeck missed a substantial element
	of continuity in women’s participation: throughout the
(40)	period women did the central work of actually
	making cheese. Their persistence in English cheese
	dairying contrasts with women’s early disappearance
	from arable agriculture in southeast England and
	from American cheese dairying. Comparing these
(45)	three divergent developments yields some reasons
	for the differences among them. English cheese-
	making women worked in a setting in which cultural
	values, agricultural conditions, and the nature of
	their work combined to support their continued
(50)	participation. In the other cases, one or more of
	these elements was lacking.