Assertion: continent's region | /r/HasProperty | covered by shallow seaways
Facets:
value: in middle
type: LOCATION
value: in early late jurassic times
type: TEMPORAL
Source sentences:
text: In Middle and early Late Jurassic times, the western regions of North America were covered by shallow seaways that advanced and retreated repeatedly, leaving successive accumulations of marine sandstones, limestones, and shales.