Complex sentence: Stella and her companion Miss McClintock were thrown from the carriage leaving Miss McClintock uninjured, however Stella hit her head against a rock gatepost, leaving her with a fractured skull, dying of her injuries two days later.
Split into simpler sentences: Stella and her companion Miss McClintock were thrown from the carriage leaving Miss McClintock uninjured. However Stella hit her head against a rock gatepost, leaving her with a fractured skull, dying of her injuries two days later.