Explanation/Reference:
Range Partitioning in Oracle
How does Oracle know how to decompose the single logical table into multiple smaller tables? The answer to this fundamental question is that the user or DBA establishes the criterion used by the database for partitioning. In the case of range partitioning, a partition key is specified. The partition key is based on one or more columns in the table that are associated with a value or range of values. Oracle uses the partition key to decide which partition (smaller table) to put each row in. For example, if the partition key is a date field, then Oracle will look at the date associated with the partition key, and insert that row into the smaller table that contains the range of dates associated with the given date.
For instance, given this table:
CREATE TABLE partn_table (in_date DATE, geom SDO_GEOMETRY)
PARTITION BY RANGE (in_date)
(PARTITION Q1_2004 VALUES LESS THAN ('01-APR-2004'),
PARTITION Q2_2004 VALUES LESS THAN ('01-JUL-2004'),
PARTITION Q3_2004 VALUES LESS THAN ('01-OCT-2004'),
PARTITION Q4_2004 VALUES LESS THAN ('01-JAN-2005')
);
The data is loaded as follows:

References: http://download.oracle.com/otndocs/products/spatial/pdf/spatial_wp10_bestprac.pdf, page 3