Scientists interpret polystrate fossils as fossils buried in a geologically short time span - either by one large depositional event or by several smaller ones. Geologists see no need to invoke a global flood to explain upright fossils. This position of geologists is supported by numerous documented examples, a few of which are discussed in the paragraphs below, of buried upright tree-trunks that have been observed buried in the Holocene volcanic deposits of Mount St. Helens, Skamania County, Washington, and Mount Pinatubo, Philippines; in the deltaic and fluvial sediments of the Mississippi River Delta; and in glacial deposits within the midwestern United States. These buried upright trees demonstrate that conventional geologic processes are capable of burying and preserving trees in an upright position such that in time, they will become fossilized.